flexible netflow configuration guide, cisco ios release 15s

Flexible Netflow Configuration Guide,Cisco IOS Release 15S

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C O N T E N T S

Cisco IOS Flexible NetFlow Overview 1

Finding Feature Information 1

Information About Flexible NetFlow 1

Typical Uses for NetFlow 2

Use of Flows in Original NetFlow and Flexible NetFlow 2

Original NetFlow and Flexible NetFlow 3

Flexible NetFlow Components 4

Records 5

NetFlow Predefined Records 5

User-Defined Records 5

Flow Monitors 5

Flow Exporters 7

Flow Samplers 9

Security Monitoring with Flexible NetFlow 10

Feature Comparison of Original NetFlow and Flexible NetFlow 10

Limitations 13

Where to Go Next 13

Additional References 13

Getting Started with Configuring Cisco IOS Flexible NetFlow 15


Prerequisites for Getting Started with Configuring Flexible NetFlow 16

Restrictions for Getting Started with Configuring Flexible NetFlow 16

Information About Getting Started with Configuring Flexible NetFlow 16

Benefit of Emulating Original NetFlow with Flexible NetFlow 16

NetFlow Original and NetFlow IPv4 Original Input Predefined Records 17

NetFlow IPv4 Original Output Predefined Record 18

NetFlow IPv6 Original Input Predefined Record 19


Flexible NetFlow MPLS Egress NetFlow 22

Flexible Netflow Configuration Guide, Cisco IOS Release 15S iii

How to Get Started with Configuring Flexible NetFlow 23

Configuring a Flow Monitor for IPv4 or IPv6 Traffic Using the Predefined Record 24

Applying an IPv4 Flow Monitor to an Interface 25


Configuring a Flow Exporter for the Flow Monitor 29

Configuration Examples for Emulating Original NetFlow Features with Flexible NetFlow 31

Example: Configuring Flexible NetFlow Egress Accounting for IPv4 and IPv6 Traffic 31

Example: Configuring Flexible NetFlow Subinterface Support 32

Example: Configuring Flexible NetFlow Multiple Export Destinations 32

Where to Go Next 33


Feature Information for Flexible NetFlow 34

Configuring Cisco IOS Flexible NetFlow with Predefined Records 39


Prerequisites for Flexible NetFlow with Predefined Records 39

Restrictions for Flexible NetFlow with Predefined Records 40

Information About Configuring Flexible NetFlow with Predefined Records 40

Flexible NetFlow Predefined Records 41

Benefits of Flexible NetFlow Predefined Records 41

NetFlow Original and NetFlow IPv4 Original Input Predefined Records 41




Autonomous System Predefined Record 46

Autonomous System ToS Predefined Record 47

BGP Next-Hop Predefined Record 48

BGP Next-Hop ToS Predefined Record 49

Destination Prefix Predefined Record 50

Destination Prefix ToS Predefined Record 51

Prefix Predefined Record 52

Prefix Port Predefined Record 53

Prefix ToS Predefined Record 55

Protocol Port Predefined Record 56

Protocol Port ToS Predefined Record 57

Source Prefix Predefined Record 58

Contents

Flexible Netflow Configuration Guide, Cisco IOS Release 15Siv

Source Prefix ToS Predefined Record 59

How to Configure a Predefined Record for the Flow Monitor 60

Configuring a Flow Monitor for IPv4 Traffic Using a Predefined Record 60

Configuring a Flow Monitor for IPv6 Traffic Using a Predefined Record 62



Configuration Examples for Flexible NetFlow with Predefined Records 67

Example: Configuring a Flexible NetFlow Predefined Record for IPv4 Traffic 67

Example: Configuring a Flexible NetFlow Predefined Record for IPv6 Traffic 67

Where to Go Next 68



Configuring Data Export for Flexible NetFlow with Flow Exporters 73


Prerequisites for Data Export for Flexible NetFlow with Flow Exporters 73

Restrictions for Data Export for Flexible NetFlow with Flow Exporters 74

Information About Data Export for Flexible NetFlow with Flow Exporters 74

Flow Exporters 74

Benefits of Flexible NetFlow Flow Exporters 74

How to Configure Data Export for Flexible NetFlow with Flow Exporters 75

Restrictions 75

Configuring the Flow Exporter 75

Configuring and Enabling Flexible NetFlow with Data Export 79

Configuration Examples for Flexible NetFlow Data Export with Flow Exporters 81

Example: Configuring Multiple Export Destinations 81

Example: Configuring Sending Export Packets Using QoS 82

Example: Configuring Version 5 Export 83

Where to Go Next 83



Customizing Flexible NetFlow Flow Records and Flow Monitors 91


Prerequisites for Customizing Flexible NetFlow Flow Records and Flow Monitors 92

Information About Customizing Flexible NetFlow Flow Records and Flow Monitors 92

Criteria for Identifying Traffic To Be Used in Analysis in Flexible NetFlow 92

Contents

Flexible Netflow Configuration Guide, Cisco IOS Release 15S v

How to Customize Flexible NetFlow Flow Records and Flow Monitors 93

Configuring a Customized Flow Record 94

Creating a Customized Flow Monitor 96

Applying a Flow Monitor to an Interface 98

Configuration Examples for Customizing Flow Records and Flow Monitors 100

Example: Configuring a Permanent Flow Record Cache with a Limited Number of Flows 100

Example: Configuring a Customized Flow Record Cache for Monitoring IPv6 Traffic 101

Example: Configuring Flexible NetFlow for Monitoring MAC and VLAN Statistics 102

Example: Configuring Flexible NetFlow for Ingress VRF Support 102

Example: Configuring Flexible NetFlow for Network-Based Application Recognition 103

Example: Configuring Flexible NetFlow for CTS Fields 103

Where to Go Next 104



Using Flexible NetFlow Flow Sampling 111


Prerequisites for Using Flow Sampling 111

Information About Flexible NetFlow Samplers 112

Flow Samplers 112

How to Configure Flexible NetFlow Flow Sampling 112

Configuring a Flow Monitor 112

Configuring and Enabling Flow Sampling 114

Configuration Examples for Using Flexible NetFlow Flow Sampling 116

Example: Configuring and Enabling a Deterministic Sampler for IPv4 Traffic 116

Example: Configuring and Enabling a Deterministic Sampler for IPv6 Traffic 117

Example: Adding a Sampler to a Flow Monitor When a Flow Monitor Is Already Enabled 117

Example: Removing a Sampler from a Flow Monitor 118


Feature Information for Flexible Netflow—Random Sampling 119

Contents

Flexible Netflow Configuration Guide, Cisco IOS Release 15Svi

Cisco IOS Flexible NetFlow Overview

NetFlow is a Cisco IOS technology that provides statistics on packets flowing through the router. NetFlowis the standard for acquiring IP operational data from IP networks. NetFlow provides data to enablenetwork and security monitoring, network planning, traffic analysis, and IP accounting.

Flexible NetFlow improves on original NetFlow by adding the capability to customize the traffic analysisparameters for your specific requirements. Flexible NetFlow facilitates the creation of more complexconfigurations for traffic analysis and data export through the use of reusable configuration components.

This module provides an overview of Flexible NetFlow and the advanced Flexible NetFlow features andservices.

• Finding Feature Information, page 1• Information About Flexible NetFlow, page 1• Where to Go Next, page 13• Additional References, page 13

Finding Feature InformationYour software release may not support all the features documented in this module. For the latest caveatsand feature information, see Bug Search Tool and the release notes for your platform and software release.To find information about the features documented in this module, and to see a list of the releases in whicheach feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support.To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.

Information About Flexible NetFlow• Typical Uses for NetFlow, page 2• Use of Flows in Original NetFlow and Flexible NetFlow, page 2• Original NetFlow and Flexible NetFlow, page 3• Flexible NetFlow Components, page 4• Security Monitoring with Flexible NetFlow, page 10• Feature Comparison of Original NetFlow and Flexible NetFlow, page 10• Limitations, page 13

Flexible Netflow Configuration Guide, Cisco IOS Release 15S 1

http://www.cisco.com/cisco/psn/bssprt/bss

http://www.cisco.com/go/cfn

Typical Uses for NetFlowNetFlow is typically used for several key customer applications, including the following:

• Network monitoring. NetFlow data enables extensive near-real-time network monitoring capabilities.Flow-based analysis techniques are used by network operators to visualize traffic patterns associatedwith individual routers and switches and network-wide traffic patterns (providing aggregate traffic orapplication-based views) to provide proactive problem detection, efficient troubleshooting, and rapidproblem resolution.

• Application monitoring and profiling. NetFlow data enables network managers to gain a detailed time-based view of application usage over the network. This information is used to plan, understand newservices, and allocate network and application resources (for example, web server sizing and VoIPdeployment) to meet customer demands responsively.

• User monitoring and profiling. NetFlow data enables network engineers to gain detailed understandingof customer and user use of network and application resources. This information may then be used toefficiently plan and allocate access, backbone, and application resources and to detect and resolvepotential security and policy violations.

• Network planning. NetFlow can be used to capture data over a long period of time, affording theopportunity to track and anticipate network growth and plan upgrades to increase the number ofrouting devices, ports, and higher-bandwidth interfaces. NetFlow services data optimizes networkplanning for peering, backbone upgrades, and routing policy. NetFlow helps to minimize the total costof network operations while maximizing network performance, capacity, and reliability. NetFlowdetects unwanted WAN traffic, validates bandwidth and quality of service (QoS), and allows theanalysis of new network applications. NetFlow will give you valuable information to reduce the costof operating your network.

• Security analysis. NetFlow identifies and classifies distributed denial of service (dDoS) attacks,viruses, and worms in real time. Changes in network behavior indicate anomalies that are clearlydemonstrated in Flexible NetFlow data. The data is also a valuable forensic tool to understand andreplay the history of security incidents.

• Billing and accounting. NetFlow data provides fine-grained metering (for instance, flow data includesdetails such as IP addresses, packet and byte counts, time stamps, type of service (ToS), andapplication ports) for highly flexible and detailed resource utilization accounting. Service providersmay use the information for billing based on time of day, bandwidth usage, application usage, qualityof service, and so on. Enterprise customers may use the information for departmental charge back orcost allocation for resource utilization.

• NetFlow data warehousing and data mining. NetFlow data (or derived information) can be warehousedfor later retrieval and analysis in support of proactive marketing and customer service programs (forexample, discovering which applications and services are being used by internal and external users andtargeting them for improved service, advertising, and so on). In addition, Flexible NetFlow data givesmarket researchers access to the "who," "what," "where," and "how long" information relevant toenterprises and service providers.

Use of Flows in Original NetFlow and Flexible NetFlowOriginal NetFlow and Flexible NetFlow both use the concept of flows. A flow is defined as a stream ofpackets between a given source and a given destination.

Original NetFlow and Flexible NetFlow both use the values in key fields in IP datagrams, such as the IPsource or destination address and the source or destination transport protocol port, as the criteria fordetermining when a new flow must be created in the cache while network traffic is being monitored. When

Typical Uses for NetFlow Information About Flexible NetFlow

Flexible Netflow Configuration Guide, Cisco IOS Release 15S2

the value of the data in the key field of a datagram is unique with respect to the flows that already exist, anew flow is created.

Original NetFlow and Flexible NetFlow both use nonkey fields as the criteria for identifying fields fromwhich data is captured from the flows. The flows are populated with data that is captured from the values inthe nonkey fields.

The figure below is an example of the process for inspecting packets and creating flow records in the cache.In this example, two unique flows are created in the cache because different values are in the source anddestination IP address key fields.

Figure 1 Packet Inspection

Original NetFlow and Flexible NetFlowOriginal NetFlow uses a fixed seven tuples of IP information to identify a flow. Flexible NetFlow allowsthe flow to be user defined. The benefits of Flexible NetFlow include:

• High-capacity flow recognition, including scalability and aggregation of flow information.• Enhanced flow infrastructure for security monitoring and dDoS detection and identification.• New information from packets to adapt flow information to a particular service or operation in the

network. The flow information available will be customizable by Flexible NetFlow users.• Extensive use of Cisco’s flexible and extensible NetFlow Version 9 export format.• A comprehensive IP accounting feature that can be used to replace many accounting features, such as

IP accounting, Border Gateway Protocol (BGP) Policy Accounting, and persistent caches.

Original NetFlow allows you to understand the activities in the network and thus to optimize networkdesign and reduce operational costs. Flexible NetFlow allows you to understand network behavior with

Original NetFlow and Flexible NetFlowInformation About Flexible NetFlow


more efficiency, with specific flow information tailored for various services used in the network. Thefollowing are some example applications for a Flexible NetFlow feature:

• Flexible NetFlow enhances Cisco NetFlow as a security monitoring tool. For instance, new flow keyscan be defined for packet length or MAC address, allowing users to search for a specific type of attackin the network.

• Flexible NetFlow allows you to quickly identify how much application traffic is being sent betweenhosts by specifically tracking TCP or UDP applications by the class of service (CoS) in the packets.

• The accounting of traffic entering a Multiprotocol Label Switching (MPLS) or IP core network and itsdestination for each next hop per class of service. This capability allows the building of an edge-to-edge traffic matrix.

The figure below is an example of how Flexible NetFlow might be deployed in a network.

Figure 2 Typical Deployment for Flexible NetFlow

Flexible NetFlow ComponentsFlexible NetFlow consists of components that can be used together in several variations to perform trafficanalysis and data export. The user-defined flow records and the component structure of Flexible NetFlowfacilitates the creation of various configurations for traffic analysis and data export on a networking devicewith a minimum number of configuration commands. Each flow monitor can have a unique combination offlow record, flow exporter, and cache type. If you change a parameter such as the destination IP address fora flow exporter, it is automatically changed for all the flow monitors that use the flow exporter. The sameflow monitor can be used in conjunction with different flow samplers to sample the same type of networktraffic at different rates on different interfaces. The following sections provide more information onFlexible NetFlow components:

• Records, page 5• Flow Monitors, page 5• Flow Exporters, page 7• Flow Samplers, page 9

Flexible NetFlow Components Information About Flexible NetFlow


RecordsIn Flexible NetFlow a combination of key and nonkey fields is called a record . Flexible NetFlow recordsare assigned to Flexible NetFlow flow monitors to define the cache that is used for storing flow data.Flexible NetFlow includes several predefined records that can help you get started using Flexible NetFlow.To use Flexible NetFlow to its fullest potential, you need to create your own customized records, asdescribed in the following section(s):

• NetFlow Predefined Records, page 5• User-Defined Records, page 5

NetFlow Predefined Records

Flexible NetFlow includes several predefined records that you can use to start monitoring traffic in yournetwork. The predefined records are available to help you quickly deploy Flexible NetFlow and are easierto use than user-defined flow records. You can choose from a list of already defined records that may meetthe needs for network monitoring. As Flexible NetFlow evolves, popular user-defined flow records will bemade available as predefined records to make them easier to implement.

The predefined records ensure backward compatibility with your existing NetFlow collector configurationsfor the data that is exported. Each of the predefined records has a unique combination of key and nonkeyfields that offer you the built-in ability to monitor various types of traffic in your network withoutcustomizing Flexible NetFlow on your router.

Two of the predefined records (NetFlow original and NetFlow IPv4/IPv6 original output), which arefunctionally equivalent, emulate original (ingress) NetFlow and the Egress NetFlow Accounting feature inoriginal NetFlow, respectively. Some of the other Flexible NetFlow predefined records are based on theaggregation cache schemes available in original NetFlow. The Flexible NetFlow predefined records that arebased on the aggregation cache schemes available in original NetFlow do not perform aggregation. Insteadeach flow is tracked separately by the predefined records.

User-Defined Records

Flexible NetFlow enables you to define your own records for a Flexible NetFlow flow monitor cache byspecifying the key and nonkey fields to customize the data collection to your specific requirements. Whenyou define your own records for a Flexible NetFlow flow monitor cache, they are referred to as user-defined records . The values in nonkey fields are added to flows to provide additional information about thetraffic in the flows. A change in the value of a nonkey field does not create a new flow. In most cases thevalues for nonkey fields are taken from only the first packet in the flow. Flexible NetFlow enables you tocapture counter values such as the number of bytes and packets in a flow as nonkey fields.

Flexible NetFlow adds a new Version 9 export format field type for the header and packet section types.Flexible NetFlow will communicate to the NetFlow collector the configured section sizes in thecorresponding Version 9 export template fields. The payload sections will have a corresponding lengthfield that can be used to collect the actual size of the collected section.

Flow MonitorsFlow monitors are the Flexible NetFlow component that is applied to interfaces to perform network trafficmonitoring.

Flow data is collected from the network traffic and added to the flow monitor cache during the monitoringprocess based on the key and nonkey fields in the flow record.

Cisco IOS Flexible NetFlow OverviewRecords


Flexible NetFlow can be used to perform different types of analysis on the same traffic. In the figure below,packet 1 is analyzed using a record designed for standard traffic analysis on the input interface and a recorddesigned for security analysis on the output interface.

Figure 3 Example of Using Two Flow Monitors to Analyze the Same Traffic

Cisco IOS Flexible NetFlow Overview Flow Monitors


The figure below shows a more complex example of how you can apply different types of flow monitorswith custom records.

Figure 4 Complex Example of Using Multiple Types of Flow Monitors with Custom Records

Normal

The default cache type is "normal." In this mode, the entries in the cache are aged out according to thetimeout active and timeout inactive settings. When a cache entry is aged out, it is removed from the cacheand exported via any exporters configured.

Flow ExportersFlow exporters export the data in the flow monitor cache to a remote system, such as a server runningNetFlow collector, for analysis and storage. Flow exporters are created as separate entities in theconfiguration. Flow exporters are assigned to flow monitors to provide data export capability for the flowmonitors. You can create several flow exporters and assign them to one or more flow monitors to provideseveral export destinations. You can create one flow exporter and apply it to several flow monitors.

NetFlow Data Export Format Version 9

The basic output of NetFlow is a flow record. Several different formats for flow records have evolved asNetFlow has matured. The most recent evolution of the NetFlow export format is known as Version 9. Thedistinguishing feature of the NetFlow Version 9 export format is that it is template-based. Templatesprovide an extensible design to the record format, a feature that should allow future enhancements toNetFlow services without requiring concurrent changes to the basic flow-record format. Using templatesprovides several key benefits:

Cisco IOS Flexible NetFlow OverviewFlow Exporters


• Third-party business partners who produce applications that provide collector or display services forNetFlow do not have to recompile their applications each time a new NetFlow feature is added.Instead, they should be able to use an external data file that documents the known template formats.

• New features can be added to NetFlow quickly without breaking current implementations.• NetFlow is "future-proofed" against new or developing protocols because the Version 9 format can be

adapted to provide support for them.

The Version 9 export format consists of a packet header followed by one or more template flow or dataflow sets. A template flow set provides a description of the fields that will be present in future data flowsets. These data flow sets may occur later within the same export packet or in subsequent export packets.Template flow and data flow sets can be intermingled within a single export packet, as illustrated in thefigure below.

Figure 5 Version 9 Export Packet

NetFlow Version 9 will periodically export the template data so the NetFlow collector will understand whatdata is to be sent and also export the data flow set for the template. The key advantage to Flexible NetFlowis that the user configures a flow record, which is effectively converted to a Version 9 template and then

Cisco IOS Flexible NetFlow Overview Flow Exporters


forwarded to the collector. The figure below is a detailed example of the NetFlow Version 9 export format,including the header, template flow, and data flow sets.

Figure 6 Detailed Example of the NetFlow Version 9 Export Format

For more information on the Version 9 export format, refer to the white paper titled Cisco IOS NetFlowVersion 9 Flow-Record Format, available at this URL: http://www.cisco.com/en/US/tech/tk648/tk362/technologies_white_paper09186a00800a3db9.shtml .

Flow SamplersFlow samplers are created as separate components in a router’s configuration. Flow samplers are used toreduce the load on the device that is running Flexible NetFlow by limiting the number of packets that areselected for analysis.

Flow sampling exchanges monitoring accuracy for router performance. When you apply a sampler to aflow monitor, the overhead load on the router of running the flow monitor is reduced because the numberof packets that the flow monitor must analyze is reduced. The reduction in the number of packets that areanalyzed by the flow monitor causes a corresponding reduction in the accuracy of the information stored inthe flow monitor’s cache.

Cisco IOS Flexible NetFlow OverviewFlow Samplers


http://www.cisco.com/en/US/tech/tk648/tk362/technologies_white_paper09186a00800a3db9.shtml




Samplers are combined with flow monitors when they are applied to an interface with the ip flow monitorcommand.

Security Monitoring with Flexible NetFlowFlexible NetFlow can be used as a network attack detection tool with capabilities to track all parts of the IPheader and even packet sections and characterize this information into flows. Security monitoring systemscan analyze Flexible NetFlow data, and upon finding an issue in the network, create a virtual bucket orvirtual cache that will be configured to track specific information and identify details about the attackpattern or worm propagation. The capability to create caches dynamically with specific informationcombined with input filtering (for example, filtering all flows to a specific destination) makes FlexibleNetFlow a powerful security monitoring tool.

One common type of attack occurs when TCP flags are used to flood open TCP requests to a destinationserver (for example, a SYN flood attack). The attacking device sends a stream of TCP SYNs to a givendestination address but never sends the ACK in response to the servers SYN-ACK as part of the TCP three-way handshake. The flow information needed for a security detection server requires the tracking of threekey fields: destination address or subnet, TCP flags, and packet count. The security detection server may bemonitoring general Flexible NetFlow information, and this data may trigger a detailed view of thisparticular attack by the Flexible NetFlow dynamically creating a new flow monitor in the router’sconfiguration. The new flow monitor might include input filtering to limit what traffic is visible in theFlexible NetFlow cache along with the tracking of the specific information to diagnose the TCP-basedattack. In this case the user may want to filter all flow information to the server destination address orsubnet to limit the amount of information the security detection server needs to evaluate. If the securitydetection server decided it understood this attack, it might then program another flow monitor to collect andexport payload information or sections of packets to take a deeper look at a signature within the packet.This example is just one of many possible ways that Flexible NetFlow can be used to detect securityincidents.

Feature Comparison of Original NetFlow and Flexible NetFlowThe table below provides a feature-by-feature comparison of original NetFlow and Flexible NetFlow.

Table 1 Feature-by-Feature Comparison of Original NetFlow and Flexible NetFlow

Feature Original NetFlow Flexible NetFlow Comments

NetFlow Data Capture Supported Supported Data capture is availablewith the predefined anduser-defined records inFlexible NetFlow.Flexible NetFlow hasseveral predefined keysthat emulate the trafficanalysis capabilities oforiginal NetFlow.

NetFlow Data Export Supported Supported Flow exporters exportdata from the FlexibleNetFlow flow monitorcaches to remotesystems.

Security Monitoring with Flexible NetFlow Flow Samplers



NetFlow for IPv6 Supported Supported IPv6 support wasremoved from originalNetFlow in Cisco IOSRelease 12.4(20)T.

The Flexible NetFlow--IPv6 Unicast Flowsfeature implementedIPv6 support for FlexibleNetFlow in Cisco IOSRelease 12.4(20)T.

MPLS-Aware NetFlow Supported Not supported --

MPLS Egress NetFlow Supported Supported The Flexible NetFlow--MPLS Egress NetFlowfeature implementedMPLS NetFlow egresssupport for FlexibleNetFlow in Cisco IOSRelease 12.4(22)T.

NetFlow BGP Next HopSupport

Supported Supported Available in thepredefined and user-defined keys in FlexibleNetFlow records.

Random Packet SampledNetFlow

Supported Supported Available with FlexibleNetFlow sampling.

NetFlow v9 ExportFormat

Supported Supported Available with FlexibleNetFlow exporters.

NetFlow SubinterfaceSupport

Supported Supported Flexible NetFlowmonitors can be assignedto subinterfaces.

NetFlow MultipleExport Destinations

Supported Supported Available with FlexibleNetFlow exporters.

NetFlow ToS-BasedRouter Aggregation

Supported Supported Available in thepredefined and user-defined records inFlexible NetFlowrecords.

NetFlow MinimumPrefix Mask for Router-Based Aggregation

Supported Supported Available in thepredefined and user-defined records.

NetFlow Input Filters Supported Not supported --

Cisco IOS Flexible NetFlow OverviewFlow Samplers



NetFlow MIB Supported Not supported --

NetFlow MIB and TopTalkers

Supported Not supported --

NetFlow MulticastSupport

Supported Supported In Cisco IOS Release12.4(9)T through12.4(20)T FlexibleNetFlow collectsstatistics for multicastflows. However, specificadditional fields such asreplication counts forbytes and packets are notsupported.

The Flexible NetFlow--IPv4 Multicast StatisticsSupport featureimplemented support forcapturing multicastreplication counts forbytes and packets inCisco IOS Release12.4(22)T.

NetFlow Layer 2 andSecurity MonitoringExports

Supported Partially supported The Flexible NetFlow--Layer 2 Fields featureimplemented support forcapturing MACaddresses and virtualLAN (VLAN) IDs inCisco IOS Release12.4(22)T.

Egress NetFlowAccounting

Supported Supported Flexible NetFlowmonitors can be used tomonitor egress traffic oninterfaces andsubinterfaces.

NetFlow Reliable Exportwith SCTP

Supported Not supported --

NetFlow Dynamic TopTalkers CLI

Supported Supported The Flexible NetFlow--Top N Talkers Supportfeature implemented inCisco IOS Release12.4(22)T provides thesame functionailty.

Cisco IOS Flexible NetFlow Overview Flow Samplers


LimitationsWhen using Flexible NetFlow to monitor outbound traffic on a router at the edge of an MPLS cloud, for IPtraffic that leaves over a VRF, the following fields are not collected and have a value of 0:

• destination mask• destination prefix• destination AS numbers• destination BGP traffic index• nexthop• BGP nexthop

Where to Go NextTo implement a basic Flexible NetFlow configuration that emulates original NetFlow traffic analysis anddata export, refer to the "Getting Started with Configuring Cisco IOS Flexible NetFlow" module. Toimplement other Flexible NetFlow configurations, refer to the Where to Go Next, page 13.

Additional ReferencesRelated Documents

Related Topic Document Title

Cisco IOS commands Cisco IOS Master Commands List, All Releases

Emulating original NetFlow with Flexible NetFlow "Getting Started with Configuring Cisco IOSFlexible NetFlow"

Configuring flow exporters to export FlexibleNetFlow data

"Configuring Data Export for Cisco IOS FlexibleNetFlow with Flow Exporters"

Customizing Flexible NetFlow for your network "Customizing Cisco IOS Flexible NetFlow FlowRecords and Flow Monitors"

Configuring flow sampling to reduce the overheadof monitoring traffic with Flexible NetFlow

"Using Cisco IOS Flexible NetFlow Flow Samplingto Reduce the CPU Overhead of Analyzing Traffic"

Configuring Flexible NetFlow using predefinedrecords

"Configuring Cisco IOS Flexible NetFlow withPredefined Records"

Using Flexible NetFlow Top N Talkers to analyzenetwork traffic

"Using Cisco IOS Flexible NetFlow Top N Talkersto Analyze Network Traffic"

Configuring IPv4 multicast statistics support forFlexible NetFlow

"Configuring IPv4 Multicast Statistics Support forCisco IOS Flexible NetFlow"

Configuration commands for Flexible NetFlow Cisco IOS Flexible NetFlow Command Reference

LimitationsWhere to Go Next


http://www.cisco.com/en/US/docs/ios/mcl/allreleasemcl/all_book.html

RFCs

RFC Title

RFC 3954 Cisco Systems NetFlow Services Export Version 9

Technical Assistance

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http://www.cisco.com/cisco/web/support/index.html

Cisco and the Cisco logo are trademarks or registered trademarks of Cisco and/or its affiliates in the U.S.and other countries. To view a list of Cisco trademarks, go to this URL: www.cisco.com/go/trademarks.Third-party trademarks mentioned are the property of their respective owners. The use of the word partnerdoes not imply a partnership relationship between Cisco and any other company. (1110R)

Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to beactual addresses and phone numbers. Any examples, command display output, network topology diagrams,and other figures included in the document are shown for illustrative purposes only. Any use of actual IPaddresses or phone numbers in illustrative content is unintentional and coincidental.

Cisco IOS Flexible NetFlow Overview





Getting Started with Configuring Cisco IOSFlexible NetFlow

This document contains information about and instructions for configuring Flexible NetFlow to emulatethe data capture, data analysis, and data export features of original NetFlow. The Flexible NetFlowequivalents of some of the other features that have been added to original NetFlow, such as NetFlowSubinterface Support and Multiple Export Destinations, are described in this document. The purpose ofthis document is to help you start using Flexible NetFlow as quickly as possible, and explains how toconfigure certain Flexible NetFlow features but does not explain them in detail. The documents listed inthe Getting Started with Configuring Cisco IOS Flexible NetFlow, page 15 contain more detailedinformation on Flexible NetFlow features.

NetFlow is a Cisco IOS technology that provides statistics on packets flowing through the router. NetFlowis the standard for acquiring IP operational data from IP networks. NetFlow provides data to supportnetwork and security monitoring, network planning, traffic analysis, and IP accounting.


• Finding Feature Information, page 15• Prerequisites for Getting Started with Configuring Flexible NetFlow, page 16• Restrictions for Getting Started with Configuring Flexible NetFlow, page 16• Information About Getting Started with Configuring Flexible NetFlow, page 16• How to Get Started with Configuring Flexible NetFlow, page 23• Configuration Examples for Emulating Original NetFlow Features with Flexible NetFlow, page 31• Where to Go Next, page 33• Additional References, page 33• Feature Information for Flexible NetFlow, page 34






Prerequisites for Getting Started with Configuring FlexibleNetFlow

• You are familiar with the information in the " Cisco IOS Flexible NetFlow Overview " module.• The networking device must be running a Cisco IOS release that supports Cisco IOS Flexible

NetFlow.

IPv4 Traffic

• The networking device must be configured for IPv4 routing.• One of the following must be enabled on your router and on any interfaces on which you want to

enable Flexible NetFlow: Cisco Express Forwarding or distributed Cisco Express Forwarding .

IPv6 Traffic


enable Flexible NetFlow: Cisco Express Forwarding IPv6 or distributed Cisco Express ForwardingIPv6.

Restrictions for Getting Started with Configuring FlexibleNetFlow

• Locally generated traffic (traffic that is generated by the router on which the Flexible NetFlow OutputAccounting feature is configured) is not counted as flow traffic for the Output Flexible NetFlowAccounting feature.

• The Flexible NetFlow Output Accounting feature counts CEF-switched packets only. Process-switched transit packets are not counted.

Information About Getting Started with Configuring FlexibleNetFlow

• Benefit of Emulating Original NetFlow with Flexible NetFlow, page 16• NetFlow Original and NetFlow IPv4 Original Input Predefined Records, page 17• NetFlow IPv4 Original Output Predefined Record, page 18• NetFlow IPv6 Original Input Predefined Record, page 19• NetFlow IPv6 Original Output Predefined Record, page 21• Flexible NetFlow MPLS Egress NetFlow, page 22

Benefit of Emulating Original NetFlow with Flexible NetFlowEmulating original NetFlow with Flexible NetFlow enables to you to deploy Flexible NetFlow quicklybecause you can use a predefined record instead of designing and configuring a custom user-defined

Benefit of Emulating Original NetFlow with Flexible NetFlow Prerequisites for Getting Started with Configuring Flexible NetFlow


record. You need only configure a flow monitor and apply it to an interface for Flexible NetFlow to startworking like original NetFlow. You can add an optional exporter if you want to analyze the data that youcollect with an application such as NetFlow collector.

Each flow monitor has a separate cache assigned to it. Each flow monitor requires a record to define thecontents and layout of its cache entries. The record format can be one of the predefined record formats, oran advanced user may create his or her own record format using the collect and matchcommands inFlexible NetFlow flow record configuration mode.

Flow exporters are used to send the data that you collect with Flexible NetFlow to a remote system such asa NetFlow Collection Engine. Exporters use UDP as the transport protocol and use the Version 9 exportformat.

If you are familiar with original NetFlow, you already understand the format and content of the data thatyou collect and export with Flexible NetFlow when you emulate original NetFlow. You will be able to usethe same techniques for analyzing the data.

NetFlow Original and NetFlow IPv4 Original Input Predefined RecordsThe Flexible NetFlow "NetFlow original" and "NetFlow IPv4 original input" predefined records can beused interchangeably because they have the same key and nonkey fields. The key and nonkey fields and thecounters for the Flexible NetFlow "NetFlow original" and "NetFlow IPv4 original input" predefinedrecords are shown in the table below.

Table 2 Key and Nonkey Fields Used by the Flexible NetFlow NetFlow Original and NetFlow IPv4 OriginalInput Predefined Records

Field Key or Nonkey Field Definition

IP ToS Key Value in the type of service (ToS)field.

IP Protocol Key Value in the IP protocol field.

IP Source Address Key IP source address.

IP Destination Address Key IP destination address.

Transport Source Port Key Value of the transport layersource port field.

Transport Destination Port Key Value of the transport layerdestination port field.

Interface Input Key Interface on which the traffic isreceived.

Flow Sampler ID Key ID number of the flow sampler (ifflow sampling is enabled).

IP Source AS Nonkey Source autonomous systemnumber.

IP Destination AS Nonkey Destination autonomous systemnumber.

NetFlow Original and NetFlow IPv4 Original Input Predefined RecordsInformation About Getting Started with Configuring Flexible NetFlow



IP Next Hop Address Nonkey IP address of the next hop.

IP Source Mask Nonkey Mask for the IP source address.

IP Destination Mask Nonkey Mask for the IP destinationaddress.

TCP Flags Nonkey Value in the TCP flag field.

Interface Output Nonkey Interface on which the traffic istransmitted.

Counter Bytes Nonkey Number of bytes seen in the flow.

Counter Packets Nonkey Number of packets seen in theflow.

Time Stamp System Uptime First Nonkey System uptime (time, inmilliseconds, since this devicewas first booted) when the firstpacket was switched.

Time Stamp System Uptime Last Nonkey System uptime (time, inmilliseconds, since this devicewas first booted) when the lastpacket was switched.

The configuration in the How to Get Started with Configuring Flexible NetFlow, page 23 uses thepredefined Flexible NetFlow "NetFlow original" record.

NetFlow IPv4 Original Output Predefined RecordThe Flexible NetFlow "NetFlow IPv4 original output" predefined record is used to emulate the originalNetFlow Egress NetFlow Accounting feature that was released in Cisco IOS Release 12.3(11)T. The keyand nonkey fields and the counters for the Flexible NetFlow "NetFlow IPv4 original output" predefinedrecord are shown in the table below.

Table 3 Key and Nonkey Fields Used by the Flexible NetFlow NetFlow IPv4 Original Output PredefinedRecord


IP ToS Key Value in the ToS field.





NetFlow IPv4 Original Output Predefined Record Information About Getting Started with Configuring Flexible NetFlow




Interface Output Key Interface on which the traffic istransmitted.








Interface Input Nonkey Interface on which the traffic isreceived.





The configuration in the Example: Configuring Flexible NetFlow Egress Accounting for IPv4 and IPv6Traffic, page 31 uses the predefined Flexible NetFlow "NetFlow original output" record.

NetFlow IPv6 Original Input Predefined RecordThe key and nonkey fields and the counters for the Flexible NetFlow "NetFlow IPv6 original input"predefined record are shown in the table below.

NetFlow IPv6 Original Input Predefined RecordInformation About Getting Started with Configuring Flexible NetFlow


Table 4 Key and Nonkey Fields Used by the Flexible NetFlow NetFlow IPv6 Original Input Predefined Record

Field Key or NonKey Field Definition

Traffic Class Key Value in the traffic class field.

Flow Label Key Flow label.

Protocol Key Value in the protocol field.

Extension Map Key Value in the extension mapbitmap.






Flow Direction Key The direction of the flow.

Flow Sampler Key ID number of the flow sampler (ifflow sampling is enabled).

Routing Source AS Nonkey Source autonomous systemnumber.

Routing Destination AS Nonkey Destination autonomous systemnumber.

Routing Next-hop Address Nonkey IP address of the next hop.



Transport TCP Flags Nonkey Value in the TCP flag field.

Interface Output Nonkey Interface over which the traffic istransmitted.



Getting Started with Configuring Cisco IOS Flexible NetFlow Information About Getting Started with Configuring Flexible NetFlow





NetFlow IPv6 Original Output Predefined RecordThe key and nonkey fields and the counters for the Flexible NetFlow "NetFlow IPv6 original output"predefined record are shown in the table below.




Flow Label Key The flow label.







Interface Output Key Interface over which the traffic istransmitted.




NetFlow IPv6 Original Output Predefined RecordInformation About Getting Started with Configuring Flexible NetFlow













Flexible NetFlow MPLS Egress NetFlowThe Flexible NetFlow--MPLS Egress NetFlow feature allows you to capture IP flow information forpackets that arrive on a router as Multiprotocol Label Switching (MPLS) packets and are transmitted as IPpackets. This feature allows you to capture the MPLS VPN IP flows that are traveling through the serviceprovider backbone from one site of a VPN to another site of the same VPN. The Flexible NetFlow--MPLSEgress NetFlow feature is enabled by applying a flow monitor in output (egress) mode on the provider edge(PE) to customer edge (CE) interface of the provider’s network.

The figure below shows a sample MPLS VPN network topology that includes four VPN 1 sites and twoVPN 2 sites. If the Flexible NetFlow--MPLS Egress NetFlow is enabled on an outgoing PE interface byapplying a flow monitor in output mode, IP flow information for packets that arrive at the PE as MPLSpackets (from an MPLS VPN) and that are transmitted as IP packets to the PE router is captured. Forexample:

• To capture the flow of traffic going to site 2 of VPN 1 from any remote VPN 1 sites, you enable a flowmonitor in output mode on link PE2-CE5 of provider edge router PE2.

• To capture the flow of traffic going to site 1 of VPN 2 from any remote VPN 2 site, you enable a flowmonitor in output mode on link PE3-CE4 of the provider edge router PE3.

Flexible NetFlow MPLS Egress NetFlow Information About Getting Started with Configuring Flexible NetFlow


The flow data is stored in the Flexible NetFlow cache. You can use the show flow monitor monitor-namecachecommand to display the flow data in the cache.

Figure 7 Sample MPLS VPN Network Topology with Flexible NetFlow--MPLS Egress NetFlow Feature

If you configure a Flexible NetFlow exporter for the flow monitors you use for the Flexible NetFlow--MPLS Egress NetFlow feature, the PE routers will export the captured flows to the configured collectordevices in the provider network. Applications such as the Network Data Analyzer or the VPN SolutionCenter (VPN-SC) can gather information from the captured flows and compute and display site-to-siteVPN traffic statistics.

How to Get Started with Configuring Flexible NetFlowThe tasks in this section explain how to configure and verify the emulation of original (ingress) NetFlowdata capture with Flexible NetFlow for traffic that is received by the router and how to configure and verifythe emulation of original NetFlow data export with Flexible NetFlow.

Note Flexible NetFlow emulation of original NetFlow requires the configuration of a flow monitor and theapplication of the flow monitor to at least one interface that is receiving the traffic that you want to analyze.

Note Only the keywords and arguments required for the Flexible NetFlow commands used in these tasks areexplained in these tasks. For information on the other keywords and arguments available for these FlexibleNetFlow commands, refer to the Cisco IOS Flexible NetFlow Command Reference .

• Configuring a Flow Monitor for IPv4 or IPv6 Traffic Using the Predefined Record, page 24• Applying an IPv4 Flow Monitor to an Interface, page 25• Applying an IPv6 Flow Monitor to an Interface, page 27• Configuring a Flow Exporter for the Flow Monitor, page 29

Getting Started with Configuring Cisco IOS Flexible NetFlowHow to Get Started with Configuring Flexible NetFlow


Configuring a Flow Monitor for IPv4 or IPv6 Traffic Using the PredefinedRecord

To configure a flow monitor for IPv4/IPv6 traffic using the Flexible NetFlow "NetFlow IPv4/IPv6 originalinput" predefined record for the flow monitor, perform the following required task.


Note You must remove a flow monitor from all of the interfaces to which you have applied it before you canmodify the record format of the flow monitor.

SUMMARY STEPS

1. enable

2. configure terminal

3. flow monitor monitor-name

4. description description

5. record netflow {ipv4 | ipv6} original-input

6. end

7. show flow monitor [[name] monitor-name [cache [format {csv | record | table}]][statistics]]

8. show running-config flow monitor monitor-name

DETAILED STEPS

Command or Action Purpose

Step 1 enable

Example:

Device> enable

Enables privileged EXEC mode.

• Enter your password if prompted.

Step 2 configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Configuring a Flow Monitor for IPv4 or IPv6 Traffic Using the Predefined Record How to Get Started with Configuring Flexible NetFlow



Step 3 flow monitor monitor-name

Example:

Device(config)# flow monitor FLOW-MONITOR-1

Creates a flow monitor and enters Flexible NetFlowflow monitor configuration mode.

• This command also allows you to modify anexisting flow monitor.

Step 4 description description

Example:

Device(config-flow-monitor)# description Used for monitoring IPv4 traffic

(Optional) Creates a description for the flow monitor.

Step 5 record netflow {ipv4 | ipv6} original-input

Example:

Device(config-flow-monitor)# record netflow ipv4 original-input

Specifies the record for the flow monitor.

Step 6 end

Example:

Device(config-flow-monitor)# end

Exits Flexible NetFlow flow monitor configurationmode and returns to privileged EXEC mode.

Step 7 show flow monitor [[name] monitor-name [cache [format {csv |record | table}]][statistics]]

Example:

Device# show flow monitor FLOW-MONITOR-2 cache

(Optional) Displays the status and statistics for aFlexible NetFlow flow monitor.

Step 8 show running-config flow monitor monitor-name

Example:

Device# show flow monitor FLOW_MONITOR-1

(Optional) Displays the configuration of the specifiedflow monitor.

Applying an IPv4 Flow Monitor to an InterfaceBefore it can be activated an IPv4 flow monitor must be applied to at least one interface. To activate anIPv4 flow monitor, perform the following required task.

Applying an IPv4 Flow Monitor to an InterfaceHow to Get Started with Configuring Flexible NetFlow


Note When you specify the "NetFlow original" or the "NetFlow IPv4 original input" predefined record for theflow monitor to emulate original NetFlow, the flow monitor can be used for analyzing only input (ingress)traffic.

When you specify the "NetFlow IPv4 original output" predefined record for the flow monitor to emulatethe Egress NetFlow Accounting feature, the flow monitor can be used for analyzing only output (egress)traffic.

SUMMARY STEPS

1. enable


3. interface type number

4. ip flow monitor monitor-name input

5. end

6. show flow interface type number

7. show flow monitor name monitor-name cache format record

DETAILED STEPS


Step 1 enable

Example:

Router> enable




Example:

Router# configure terminal


Step 3 interface type number

Example:

Router(config)# interface ethernet 0/0

Specifies an interface and enters interface configurationmode.

Step 4 ip flow monitor monitor-name input

Example:

Router(config-if)# ip flow monitor FLOW-MONITOR-1 input

Activates the flow monitor that you created previouslyby assigning it to the interface to analyze traffic.

Getting Started with Configuring Cisco IOS Flexible NetFlow How to Get Started with Configuring Flexible NetFlow



Step 5 end

Example:

Router(config-if)# end

Exits interface configuration mode and returns toprivileged EXEC mode.

Step 6 show flow interface type number

Example:

Router# show flow interface ethernet 0/0

Displays the status of Flexible NetFlow (enabled ordisabled) on the specified interface.

Step 7 show flow monitor name monitor-name cache format record

Example:

Router# show flow monitor name FLOW_MONITOR-1 cache format record

Displays the status, statistics, and flow data in the cachefor the specified flow monitor.

Applying an IPv6 Flow Monitor to an InterfaceBefore it can be activated an IPv6 flow monitor must be applied to at least one interface. To activate anIPv6 flow monitor, perform the following required task.

Note When you specify the "NetFlow IPv6 original input" predefined record for the flow monitor to emulateoriginal NetFlow, the flow monitor can be used for analyzing only input (ingress) traffic.


SUMMARY STEPS

1. enable



4. ipv6 flow monitor monitor-name input

5. end



Applying an IPv6 Flow Monitor to an InterfaceHow to Get Started with Configuring Flexible NetFlow


DETAILED STEPS


Step 1 enable

Example:

Router> enable




Example:




Example:



Step 4 ipv6 flow monitor monitor-name input

Example:

Router(config-if)# ipv6 flow monitor FLOW-MONITOR-2 input


Step 5 end

Example:




Example:

Router# show flow interface ethernet 0/0



Example:

Router# show flow monitor name FLOW_MONITOR-1 cache format record

Displays the status, statistics, and flow data in the cachefor the specified flow monitor.



Configuring a Flow Exporter for the Flow MonitorTo configure a flow exporter for the flow monitor, in order to export the data that is collected by FlexibleNetFlow to a remote system for further analysis and storage, perform the following optional task.

Flow exporters are used to send the data that you collect with Flexible NetFlow to a remote system such asa NetFlow Collection Engine. Exporters use UDP as the transport protocol and use the Version 9 exportformat.

Note Each flow exporter supports only one destination. If you want to export the data to multiple destinations,you must configure multiple flow exporters and assign them to the flow monitor.

You can export to a destination using either an IPv4 or IPv6 address.

SUMMARY STEPS

1. enable


3. flow exporter exporter-name


5. destination {hostname | ip-address} [vrf vrf-name]

6. export-protocol {netflow-v5 | netflow-v9 | ipfix}

7. transport udp udp-port

8. exit

9. flow monitor flow-monitor-name

10. exporter exporter-name

11. end

12. show flow exporter exporter-name

13. show running-config flow exporter exporter-name

DETAILED STEPS


Step 1 enable

Example:

Device> enable




Example:



Configuring a Flow Exporter for the Flow MonitorHow to Get Started with Configuring Flexible NetFlow



Step 3 flow exporter exporter-name

Example:

Device(config)# flow exporter EXPORTER-1

Creates a flow exporter and enters Flexible NetFlow flowexporter configuration mode.

• This command also allows you to modify an existingflow exporter.


Example:

Device(config-flow-exporter)# description Exports to datacenter

(Optional) Creates a description for the flow exporter.

Step 5 destination {hostname | ip-address} [vrf vrf-name]

Example:

Device(config-flow-exporter)# destination 172.16.10.2

Specifies the hostname or IP address of the system to whichthe exporter sends data.

Note You can export to a destination using either an IPv4 orIPv6 address.

Step 6 export-protocol {netflow-v5 | netflow-v9 | ipfix}

Example:

Device(config-flow-exporter)# export-protocol netflow-v9

Specifies the version of the NetFlow export protocol used bythe exporter.

• Default: netflow-v9.

Step 7 transport udp udp-port

Example:

Device(config-flow-exporter)# transport udp 65

Configures UDP as the transport protocol and specifies theUDP port on which the destination system is listening forexported Flexible NetFlow traffic.

Step 8 exit

Example:

Device(config-flow-exporter)# exit

Exits Flexible NetFlow flow exporter configuration mode andreturns to global configuration mode.

Step 9 flow monitor flow-monitor-name

Example:


Enters Flexible NetFlow flow monitor configuration mode forthe flow monitor that you created previously.




Step 10 exporter exporter-name

Example:

Device(config-flow-monitor)# exporter EXPORTER-1

Specifies the name of an exporter that you created previously.

Step 11 end

Example:


Exits Flexible NetFlow flow monitor configuration mode andreturns to privileged EXEC mode.

Step 12 show flow exporter exporter-name

Example:

Device# show flow exporter FLOW_EXPORTER-1

(Optional) Displays the current status of the specified flowexporter.

Step 13 show running-config flow exporter exporter-name

Example:

Device<# show running-config flow exporter FLOW_EXPORTER-1

(Optional) Displays the configuration of the specified flowexporter.

Configuration Examples for Emulating Original NetFlowFeatures with Flexible NetFlow

• Example: Configuring Flexible NetFlow Egress Accounting for IPv4 and IPv6 Traffic, page 31• Example: Configuring Flexible NetFlow Subinterface Support, page 32• Example: Configuring Flexible NetFlow Multiple Export Destinations, page 32

Example: Configuring Flexible NetFlow Egress Accounting for IPv4 and IPv6Traffic

The following example shows how to configure Flexible NetFlow egress accounting for IPv4 and IPv6traffic.

This sample starts in global configuration mode:

!flow monitor FLOW-MONITOR-1 record netflow ipv4 original-output

Example: Configuring Flexible NetFlow Egress Accounting for IPv4 and IPv6 TrafficConfiguration Examples for Emulating Original NetFlow Features with Flexible NetFlow


exit!!flow monitor FLOW-MONITOR-2 record netflow ipv6 original-output exit!ip cefipv6 cef!interface Ethernet0/0 ip address 172.16.6.2 255.255.255.0 ipv6 address 2001:DB8:2:ABCD::2/48 ip flow monitor FLOW-MONITOR-1 output ipv6 flow monitor FLOW-MONITOR-2 output!

Example: Configuring Flexible NetFlow Subinterface SupportThe following example shows how to configure Flexible NetFlow subinterface support for IPv4 traffic.


!flow monitor FLOW-MONITOR-1 record netflow ipv4 original-input exit!ip cef!interface Ethernet0/0.1 ip address 172.16.6.2 255.255.255.0 ip flow monitor FLOW-MONITOR-1 input!

The following example shows how to configure Flexible NetFlow to emulate NetFlow subinterface supportfor IPv6 traffic.


!flow monitor FLOW-MONITOR-2 record netflow ipv6 original-input exit!ip cefipv6 cef!interface Ethernet0/0.1 ipv6 address 2001:DB8:2:ABCD::2/48 ipv6 flow monitor FLOW-MONITOR-2 input!

Example: Configuring Flexible NetFlow Multiple Export DestinationsThe following example shows how to configure Flexible NetFlow multiple export destinations.


!flow exporter EXPORTER-1 destination 172.16.10.2 transport udp 90 exit!flow exporter EXPORTER-2 destination 172.16.10.3

Example: Configuring Flexible NetFlow Subinterface Support Configuration Examples for Emulating Original NetFlow Features with Flexible NetFlow


transport udp 90 exit!flow monitor FLOW-MONITOR-1 record netflow-original exporter EXPORTER-2 exporter EXPORTER-1 exit!ip cef!interface GigabitEthernet0/0/0 ip address 172.16.6.2 255.255.255.0 ip flow monitor FLOW-MONITOR-1 input!

Where to Go NextFor information on advanced Flexible NetFlow configurations for specific purposes such as quality ofservice (QoS) and bandwidth monitoring, application and user flow monitoring and profiling, and securityanalysis, refer to the "Customizing Cisco IOS Flexible NetFlow Flow Records and Flow Monitors"module.

If you want to configure additional options for data export for Flexible NetFlow, refer to the "ConfiguringData Export for Cisco IOS Flexible NetFlow with Flow Exporters" module.

If you want to configure flow sampling to reduce the CPU overhead of analyzing traffic, refer to the "UsingCisco IOS Flexible NetFlow Flow Sampling to Reduce the CPU Overhead of Analyzing Traffic" module.

If you want to configure any of the predefined records for Flexible NetFlow refer, to the "ConfiguringCisco IOS Flexible NetFlow with Predefined Records" module.




Overview of Flexible NetFlow "Cisco IOS Flexible NetFlow Overview"



Customizing Flexible NetFlow "Customizing Cisco IOS Flexible NetFlow FlowRecords and Flow Monitors"





Getting Started with Configuring Cisco IOS Flexible NetFlowWhere to Go Next









Standards

Standard Title

None --

MIBs

MIB MIBs Link

None To locate and download MIBs for selectedplatforms, Cisco software releases, and feature sets,use Cisco MIB Locator found at the followingURL:

http://www.cisco.com/go/mibs

RFCs

RFC Title



Description Link

The Cisco Support and Documentation websiteprovides online resources to downloaddocumentation, software, and tools. Use theseresources to install and configure the software andto troubleshoot and resolve technical issues withCisco products and technologies. Access to mosttools on the Cisco Support and Documentationwebsite requires a Cisco.com user ID and password


Feature Information for Flexible NetFlowThe following table provides release information about the feature or features described in this module.This table lists only the software release that introduced support for a given feature in a given software

Getting Started with Configuring Cisco IOS Flexible NetFlow Feature Information for Flexible NetFlow



http://www.cisco.com/public/support/tac/home.shtml


release train. Unless noted otherwise, subsequent releases of that software release train also support thatfeature.


Getting Started with Configuring Cisco IOS Flexible NetFlowFeature Information for Flexible NetFlow



Table 6 Feature Information for Flexible NetFlow

Feature Name Releases Feature Information

Flexible NetFlow 12.2(33)SRC

12.2(50)SY

12.4(9)T

15.0(1)SY

15.0(1)SY1

Flexible NetFlow is introduced.

Support for this feature wasadded for Cisco 7200 seriesrouters in Cisco IOS Release12.2(33)SRC.

The following commands wereintroduced or modified: cache(Flexible NetFlow), clear flowexporter, clear flow monitor,clear sampler, collect counter,collect flow, collect interface,collect ipv4, collect ipv4destination, collect ipv4fragmentation, collect ipv4section, collect ipv4 source,collect ipv4 total-length, collectipv4 ttl, collect routing, collecttimestamp sys-uptime, collecttransport, collect transporticmp ipv4, collect transport tcp,collect transport udp, debugflow exporter, debug flowmonitor, debug flow record,debug sampler, description(Flexible NetFlow), destination,dscp (Flexible NetFlow),exporter, flow exporter, flowmonitor, flow platform, flowrecord, ip flow monitor, matchflow, match interface (FlexibleNetFlow), match ipv4, matchipv4 destination, match ipv4fragmentation, match ipv4section, match ipv4 source,match ipv4 total-length, matchipv4 ttl, match routing, matchtransport, match transporticmp ipv4, match transport tcp,match transport udp, mode(Flexible NetFlow), option(Flexible NetFlow), record,sampler, show flow exporter,show flow interface, show flowmonitor, show flow record,show sampler, source (FlexibleNetFlow), statistics packet,

Getting Started with Configuring Cisco IOS Flexible NetFlow Feature Information for Flexible NetFlow



template data timeout,transport (Flexible NetFlow).

Flexible NetFlow--IPv6 UnicastFlows

12.2(33)SRE

12.2(50)SY

12.4(20)T

15.0(1)SY

15.0(1)SY1

Enables Flexible NetFlow tomonitor IPv6 traffic.

Support for this feature wasadded for Cisco 7200 and 7300NPE series routers in Cisco IOSRelease 12.2(33)SRE.

The following commands wereintroduced or modified: collectrouting, debug flow record,match routing, record, showflow monitor, show flow record,collect ipv6, collect ipv6destination, collect ipv6extension map, collect ipv6fragmentation, collect ipv6 hop-limit, collect ipv6 length, collectipv6 section, collect ipv6 source,collect transport icmp ipv6,ipv6 flow monitor, match ipv6,match ipv6 destination, matchipv6 extension map, match ipv6fragmentation, match ipv6 hop-limit, match ipv6 length, matchipv6 section, match ipv6 source,match transport icmp ipv6.

Flexible NetFlow--MPLS EgressNetFlow

12.2(33)SRE

12.2(50)SY

12.4(22)T

15.0(1)SY

15.0(1)SY1

The Flexible NetFlow--MPLSEgress NetFlow feature allowsyou to capture IP flowinformation for packetsundergoing MPLS labeldisposition; that is, packets thatarrive on a router as MPLSpackets and are transmitted as IPpackets.

Support for this feature wasadded for Cisco 7200 and 7300NPE series routers in Cisco IOSRelease 12.2(33)SRE.

No commands were introduced ormodified by this feature.

Getting Started with Configuring Cisco IOS Flexible NetFlowFeature Information for Flexible NetFlow



Flexible NetFlow: Export to anIPv6 Address

15.2(2)T This feature enables FlexibleNetFlow to export data to adestination using an IPv6 address.

The following commands wereintroduced or modified:destination

Flexible NetFlow: IPFIX ExportFormat

15.2(4)M Enables sending export packetsusing the IPFIX export protocol.The export of extracted fieldsfrom NBAR is only supportedover IPFIX.

Support for this feature wasadded for Cisco ASR 1000 SeriesAggregation Services routers inCisco IOS XE Release 3.7S.

The following command wasintroduced: export-protocol.



Getting Started with Configuring Cisco IOS Flexible NetFlow



Configuring Cisco IOS Flexible NetFlow withPredefined Records

This module contains information about and instructions for configuring Flexible NetFlow usingpredefined records. Many of the Flexible NetFlow predefined records use the same key and nonkey fieldsas the aggregation caches available in original NetFlow. However, the predefined Flexible NetFlowrecords do not perform aggregation.

NetFlow is a Cisco IOS technology that provides statistics on packets flowing through a router. NetFlowis the standard for acquiring IP operational data from IP networks. NetFlow provides data to supportnetwork and security monitoring, network planning, traffic analysis, and IP accounting.


• Finding Feature Information, page 39• Prerequisites for Flexible NetFlow with Predefined Records, page 39• Restrictions for Flexible NetFlow with Predefined Records, page 40• Information About Configuring Flexible NetFlow with Predefined Records, page 40• How to Configure a Predefined Record for the Flow Monitor, page 60• Configuration Examples for Flexible NetFlow with Predefined Records, page 67• Where to Go Next, page 68• Additional References, page 68• Feature Information for Flexible NetFlow, page 69



Prerequisites for Flexible NetFlow with Predefined Records• You are familiar with the information in the " Cisco IOS Flexible NetFlow Overview " module.




• The networking device must be running a Cisco IOS release that supports Flexible NetFlow.

IPv4 Traffic


enable Flexible NetFlow: Cisco Express Forwarding or distributed Cisco Express Forwarding.

IPv6 Traffic



Restrictions for Flexible NetFlow with Predefined RecordsCisco IOS Release 12.2(50)SY

• Predefined records specifying mask and prefix are not supported.

Information About Configuring Flexible NetFlow withPredefined Records

• Flexible NetFlow Predefined Records, page 41• Benefits of Flexible NetFlow Predefined Records, page 41• NetFlow Original and NetFlow IPv4 Original Input Predefined Records, page 41• NetFlow IPv4 Original Output Predefined Record, page 42• NetFlow IPv6 Original Input Predefined Record, page 43• NetFlow IPv6 Original Input Predefined Record, page 45• Autonomous System Predefined Record, page 46• Autonomous System ToS Predefined Record, page 47• BGP Next-Hop Predefined Record, page 48• BGP Next-Hop ToS Predefined Record, page 49• Destination Prefix Predefined Record, page 50• Destination Prefix ToS Predefined Record, page 51• Prefix Predefined Record, page 52• Prefix Port Predefined Record, page 53• Prefix ToS Predefined Record, page 55• Protocol Port Predefined Record, page 56• Protocol Port ToS Predefined Record, page 57• Source Prefix Predefined Record, page 58• Source Prefix ToS Predefined Record, page 59

Configuring Cisco IOS Flexible NetFlow with Predefined Records Restrictions for Flexible NetFlow with Predefined Records


Flexible NetFlow Predefined RecordsFlexible NetFlow predefined records are based on the original NetFlow ingress and egress caches and theaggregation caches. The difference between the original NetFlow aggregation caches and the correspondingpredefined Flexible NetFlow records is that the predefined records do not perform aggregation. FlexibleNetFlow predefined records are associated with a Flexible NetFlow flow monitor the same way that youassociate a user-defined (custom) record.

Benefits of Flexible NetFlow Predefined RecordsIf you have been using original NetFlow or original NetFlow with aggregation caches you can continue tocapture the same traffic data for analysis when you migrate to Flexible NetFlow by using the predefinedrecords available with Flexible NetFlow. Many users will find that the preexisting Flexible NetFlowrecords are suitable for the majority of their traffic analysis requirements.

NetFlow Original and NetFlow IPv4 Original Input Predefined RecordsThe Flexible NetFlow "NetFlow original" and "NetFlow IPv4 original input" predefined records can beused interchangeably because they have the same key and nonkey fields. The key and nonkey fields and thecounters for the Flexible NetFlow "NetFlow original" and "NetFlow IPv4 original input" predefinedrecords are shown in the table below.

Table 7 Key and Nonkey Fields Used by the Flexible NetFlow NetFlow Original and NetFlow IPv4 OriginalInput Predefined Records


IP ToS Key Value in the type of service (ToS)field.









Flexible NetFlow Predefined RecordsInformation About Configuring Flexible NetFlow with Predefined Records








Interface Output Nonkey Interface on which the traffic istransmitted.





The configuration in the How to Get Started with Configuring Flexible NetFlow, page 23 uses thepredefined Flexible NetFlow "NetFlow original" record.

NetFlow IPv4 Original Output Predefined RecordThe Flexible NetFlow "NetFlow IPv4 original output" predefined record is used to emulate the originalNetFlow Egress NetFlow Accounting feature that was released in Cisco IOS Release 12.3(11)T. The keyand nonkey fields and the counters for the Flexible NetFlow "NetFlow IPv4 original output" predefinedrecord are shown in the table below.







NetFlow IPv4 Original Output Predefined Record Information About Configuring Flexible NetFlow with Predefined Records


















The configuration in the Example: Configuring Flexible NetFlow Egress Accounting for IPv4 and IPv6Traffic, page 31 uses the predefined Flexible NetFlow "NetFlow original output" record.


NetFlow IPv6 Original Input Predefined RecordInformation About Configuring Flexible NetFlow with Predefined Records
























Configuring Cisco IOS Flexible NetFlow with Predefined Records Information About Configuring Flexible NetFlow with Predefined Records





















NetFlow IPv6 Original Input Predefined RecordInformation About Configuring Flexible NetFlow with Predefined Records












Autonomous System Predefined RecordThe Flexible NetFlow "autonomous system" predefined record creates flows based on autonomous system-to-autonomous system traffic flow data. The Flexible NetFlow "autonomous system" predefined recorduses the same key and nonkey fields as the original NetFlow "autonomous system" aggregation cache.

Note This predefined record can be used to analyze IPv4 and IPv6 traffic.

The table below lists the key and nonkey fields used in the Flexible NetFlow "autonomous system"predefined record.

Table 11 Key and Nonkey Fields Used by the Flexible NetFlow Autonomous System Predefined Record


IP Source AS Key Autonomous system of the sourceIP address (peer or origin).

IP Destination AS Key Autonomous system of thedestination IP address (peer ororigin).

Autonomous System Predefined Record Information About Configuring Flexible NetFlow with Predefined Records





Flow Direction Key Direction in which the flow isbeing monitored.



Time Stamp System Uptime First Nonkey System uptime (time, inmilliseconds since this devicewas first booted) when the firstpacket was switched.

Time Stamp System Uptime Last Nonkey System uptime (time, inmilliseconds since this devicewas first booted) when the lastpacket was switched.

Autonomous System ToS Predefined RecordThe Flexible NetFlow "autonomous system ToS" predefined record creates flows based on autonomoussystem-to-autonomous system and type of service (ToS) traffic flow data. The Flexible NetFlow"autonomous system ToS" predefined record uses the same key and nonkey fields as the original NetFlow"autonomous system ToS" aggregation cache.

Note This predefined record can be used to analyze only IPv4 traffic.

Tip This predefined record is particularly useful for generating autonomous system-to-autonomous systemtraffic flow data.

The table below lists the key and nonkey fields used in the Flexible NetFlow "autonomous system ToS"predefined record.

Table 12 Key and Nonkey Fields Used by the Flexible NetFlow Autonomous System ToS Predefined Record



IP Source autonomous system Key Autonomous system of the sourceIP address (peer or origin).

Autonomous System ToS Predefined RecordInformation About Configuring Flexible NetFlow with Predefined Records



IP Destination autonomoussystem

Key Autonomous system of thedestination IP address (peer ororigin).








BGP Next-Hop Predefined RecordThe Flexible NetFlow "BGP next-hop" predefined record creates flows based on Border Gateway Protocol(BGP) traffic flow data.


The table below lists the key and nonkey fields used in the Flexible NetFlow "BGP next-hop" predefinedrecord.

Table 13 Key and Nonkey Fields Used by the Flexible NetFlow BGP Next-Hop Predefined Record


Routing Source AS Key Autonomous system of the sourceIP address.

Routing Destination AS Key Autonomous system of thedestination IP address.

BGP Next-Hop Predefined Record Information About Configuring Flexible NetFlow with Predefined Records



Routing Next-hop Address IPv6BGP

Key IPv6 address of the BGP nexthop.






Timestamp Sys-uptime First Nonkey System uptime (time, inmilliseconds, since this devicewas first booted) when the firstpacket was switched.

Timestamp Sys-uptime Last Nonkey System uptime (time, inmilliseconds, since this devicewas first booted) when the lastpacket was switched.

BGP Next-Hop ToS Predefined RecordThe Flexible NetFlow "BGP next-hop ToS" predefined record creates flows based on BGP and ToS trafficflow data. The Flexible NetFlow "BGP next-hop ToS" predefined record uses the same key and nonkeyfields as the original NetFlow "BGP next-hop ToS" aggregation cache.


The table below lists the key and nonkey fields used in the "BGP next-hop ToS" predefined record.

Table 14 Key and Nonkey Fields Used by the Flexible NetFlow BGP Next-Hop ToS Predefined Record






BGP Next-Hop ToS Predefined RecordInformation About Configuring Flexible NetFlow with Predefined Records



IPv4 Next Hop Address BGP Key IPv4 address of the BGP nexthop.








Destination Prefix Predefined RecordThe Flexible NetFlow "destination prefix" predefined record creates flows based on destination prefixtraffic flow data. The Flexible NetFlow "destination prefix" predefined record uses the same key andnonkey fields as the original NetFlow "destination prefix" aggregation cache.


The table below lists the key and nonkey fields used in the Flexible NetFlow "destination prefix"predefined record.

Table 15 Key and Nonkey Fields Used by the Flexible NetFlow Destination Prefix Predefined Record




IPv4 or IPv6 Destination Prefix Key Destination IP address ANDedwith the destination prefix mask.

Destination Prefix Predefined Record Information About Configuring Flexible NetFlow with Predefined Records



IPv4 or IPv6 Destination Mask Key Number of bits in the destinationprefix.







Destination Prefix ToS Predefined RecordThe Flexible NetFlow "destination prefix ToS" predefined record creates flows based on destination prefixand ToS traffic flow data. The Flexible NetFlow "destination prefix ToS" predefined record uses the samekey and nonkey fields as the original NetFlow "destination prefix ToS" aggregation cache.

This predefined record is particularly useful for capturing data with which you can examine the destinationsof network traffic passing through a NetFlow-enabled device.


The table below lists the key and nonkey fields used in the Flexible NetFlow "destination prefix ToS"predefined record.

Table 16 Key and Nonkey Fields Used by the Flexible NetFlow Destination Prefix ToS Predefined Record





Destination Prefix ToS Predefined RecordInformation About Configuring Flexible NetFlow with Predefined Records



IPv4 Destination Prefix Key Destination IP address ANDedwith the destination prefix mask.

IPv4 Destination Mask Key Number of bits in the destinationprefix.







Prefix Predefined RecordThe Flexible NetFlow "prefix" predefined record creates flows based on the source and destination prefixesin the traffic flow data. The Flexible NetFlow "prefix" predefined record uses the same key and nonkeyfields as the original NetFlow "prefix" aggregation cache.

Note This predefined record can be used to analyze IPv4 and IPv6 traffic. For IPv6 traffic, a minimum prefixmask length of 0 bits is assumed.

The table below lists the key and nonkey fields used in the Flexible NetFlow "prefix" predefined record.

Table 17 Key and Nonkey Fields Used by the Flexible NetFlow Prefix Predefined Record





Prefix Predefined Record Information About Configuring Flexible NetFlow with Predefined Records



IPv4 or IPv6 Source Prefix Key Source IP address ANDed withthe source prefix mask, or theprefix to which the source IPaddress of the aggregated flowsbelongs.

IPv4 or IPv6 Source Mask Key Number of bits in the sourceprefix.

IPv4 or IPv6 Destination Prefix Key Destination IP address ANDedwith the destination prefix mask.

IPv4 or IPv6 Destination Mask Key Number of bits in the destinationprefix.







Prefix Port Predefined RecordThe Flexible NetFlow "prefix port" predefined record creates flows based on source and destinationprefixes and ports in the traffic flow data. The Flexible NetFlow "prefix port" predefined record uses thesame key and nonkey fields as the original NetFlow "prefix port" aggregation cache.

This predefined record is particularly useful for capturing data with which you can examine the sources anddestinations of network traffic passing through a NetFlow-enabled device.


The table below lists the key and nonkey fields used in the destination Flexible NetFlow "prefix port"predefined record.

Prefix Port Predefined RecordInformation About Configuring Flexible NetFlow with Predefined Records


Table 18 Key and Nonkey Fields Used by the Flexible NetFlow Prefix Port Predefined Record




IPv4 Source Prefix Key Source IP address ANDed withthe source prefix mask, or theprefix to which the source IPaddress of the aggregated flowsbelongs.

IPv4 Source Mask Key Number of bits in the sourceprefix.



Transport Source Port Key Value in the transport layersource port field.

Transport Destination Port Key Value in the transport layerdestination port field.








Configuring Cisco IOS Flexible NetFlow with Predefined Records Information About Configuring Flexible NetFlow with Predefined Records


Prefix ToS Predefined RecordThe Flexible NetFlow "prefix ToS" predefined record creates flows based on source and destinationprefixes and ToS traffic flow data. The Flexible NetFlow "prefix ToS" predefined record uses the same keyand nonkey fields as the original NetFlow "destination prefix ToS" aggregation cache.

This predefined record is particularly useful for capturing data with which you can examine the sources anddestinations of network traffic passing through a NetFlow-enabled device.


The table below lists the key and nonkey fields used in the Flexible NetFlow "prefix ToS" predefinedrecord.

Table 19 Key and Nonkey Fields Used by the Flexible NetFlow Prefix ToS Predefined Record














Prefix ToS Predefined RecordInformation About Configuring Flexible NetFlow with Predefined Records






Protocol Port Predefined RecordThe Flexible NetFlow "protocol port" predefined record creates flows based on protocols and ports in thetraffic flow data. The Flexible NetFlow "protocol port" predefined record uses the same key and nonkeyfields as the original NetFlow "protocol port" aggregation cache.


The table below lists the key and nonkey fields used in the Flexible NetFlow "protocol port" predefinedrecord.

Table 20 Key and Nonkey Fields Used by the Flexible NetFlow Protocol Port Predefined Record









Protocol Port Predefined Record Information About Configuring Flexible NetFlow with Predefined Records




Protocol Port ToS Predefined RecordThe Flexible NetFlow "protocol port ToS" predefined record creates flows based on the protocol, port, andToS value in the traffic data. The Flexible NetFlow "protocol port ToS" predefined record uses the samekey and nonkey fields as the original NetFlow "protocol port ToS" aggregation cache.

This predefined record is particularly useful for capturing data with which you can examine network usageby type of traffic.


The table below lists the key and nonkey fields used in the Flexible NetFlow "protocol port ToS"predefined record.

Table 21 Key and Nonkey Fields Used by the Flexible NetFlow Protocol Port ToS Predefined Record










Protocol Port ToS Predefined RecordInformation About Configuring Flexible NetFlow with Predefined Records




Source Prefix Predefined RecordThe Flexible NetFlow "source prefix" predefined record creates flows based on source prefixes in thenetwork traffic. The Flexible NetFlow "source prefix" predefined record uses the same key and nonkeyfields as the original NetFlow "source prefix" aggregation cache.


The table below lists the key and nonkey fields used in the Flexible NetFlow "source prefix" predefinedrecord.

Table 22 Key and Nonkey Fields Used by the Flexible NetFlow Source Prefix Predefined Record



IPv4 or IPv6 Source Prefix Key Source IP address ANDed withthe source prefix mask, or theprefix to which the source IPaddress of the aggregated flowsbelongs.

IPv4 or IPv6 Source Mask Key Number of bits in the sourceprefix.






Source Prefix Predefined Record Information About Configuring Flexible NetFlow with Predefined Records




Source Prefix ToS Predefined RecordThe Flexible NetFlow "source prefix ToS" predefined record creates flows based on source prefixes andToS values in the network traffic. The Flexible NetFlow "source prefix ToS" predefined record uses thesame key and nonkey fields as the original NetFlow "source prefix ToS" aggregation cache.

This predefined record is particularly useful for capturing data with which you can examine the sources ofnetwork traffic passing through a NetFlow-enabled device.


The table below lists the key and nonkey fields used in the Flexible NetFlow "source prefix ToS"predefined record.

Table 23 Key and Nonkey Fields Used by the Flexible NetFlow Source Prefix ToS Predefined Record










Source Prefix ToS Predefined RecordInformation About Configuring Flexible NetFlow with Predefined Records





How to Configure a Predefined Record for the Flow Monitor

Note Only the keywords and arguments required for the Flexible NetFlow commands used in these tasks areexplained in these tasks. For information on the other keywords and arguments available for these FlexibleNetFlow commands, refer to the Cisco IOS Flexible NetFlow Command Reference.

• Configuring a Flow Monitor for IPv4 Traffic Using a Predefined Record, page 60• Configuring a Flow Monitor for IPv6 Traffic Using a Predefined Record, page 62• Applying an IPv4 Flow Monitor to an Interface, page 64• Applying an IPv6 Flow Monitor to an Interface, page 65

Configuring a Flow Monitor for IPv4 Traffic Using a Predefined RecordTo configure a flow monitor for IPv4 traffic using a predefined record for the flow monitor, perform thefollowing required task.


Note You must remove a flow monitor from all of the interfaces on which you have applied it before you canmodify the record format of the flow monitor.

Configuring a Flow Monitor for IPv4 Traffic Using a Predefined Record How to Configure a Predefined Record for the Flow Monitor


SUMMARY STEPS

1. enable




5. record {netflow-original | netflow ipv4 record [peer]}

6. end

7. show flow record record-name

8. show running-config flow record record-name

DETAILED STEPS


Step 1 enable

Example:

Router> enable




Example:




Example:

Router(config)# flow monitor FLOW-MONITOR-1




Example:

Router(config-flow-monitor)# description Used for monitoring IPv4 traffic


Step 5 record {netflow-original | netflow ipv4 record [peer]}

Example:

Router(config-flow-monitor)# record netflow ipv4 original-input


Configuring Cisco IOS Flexible NetFlow with Predefined RecordsHow to Configure a Predefined Record for the Flow Monitor



Step 6 end

Example:

Router(config-flow-monitor)# end

Exits Flexible NetFlowflow monitor configurationmode and returns to privileged EXEC mode.

Step 7 show flow record record-name

Example:

Router# show flow record FLOW_RECORD-1

(Optional) Displays the current status of the specifiedflow record.

Step 8 show running-config flow record record-name

Example:

Router# show running-config flow record FLOW_RECORD-1

(Optional) Displays the configuration of the specifiedflow record.

Configuring a Flow Monitor for IPv6 Traffic Using a Predefined RecordTo configure a flow monitor for IPv6 traffic using a predefined record for the flow monitor, perform thefollowing required task.


Note You must remove a flow monitor from all of the interfaces on which you have applied it before you canmodify the record format of the flow monitor.

SUMMARY STEPS

1. enable




5. record netflow ipv6 record [peer]

6. end



Configuring a Flow Monitor for IPv6 Traffic Using a Predefined Record How to Configure a Predefined Record for the Flow Monitor


DETAILED STEPS


Step 1 enable

Example:

Router> enable




Example:




Example:

Router(config)# flow monitor FLOW-MONITOR-2




Example:

Router(config-flow-monitor)# description Used for monitoring IPv6 traffic


Step 5 record netflow ipv6 record [peer]

Example:

Router(config-flow-monitor)# record netflow ipv6 original-input


Step 6 end

Example:

Router(config-flow-monitor)# end



Example:

Router# show flow record FLOW_RECORD-1

(Optional) Displays the current status of the specifiedflow record.

Configuring Cisco IOS Flexible NetFlow with Predefined RecordsHow to Configure a Predefined Record for the Flow Monitor




Example:

Router# show running-config flow record FLOW_RECORD-1

(Optional) Displays the configuration of the specifiedflow record.

Applying an IPv4 Flow Monitor to an InterfaceBefore it can be activated, an IPv4 flow monitor must be applied to at least one interface. To activate anIPv4 flow monitor by applying the flow monitor to an interface, perform the following required task.

Note When you specify the "NetFlow original" or the "NetFlow IPv4 original input" predefined record for theflow monitor to emulate original NetFlow, the flow monitor can be used for analyzing only input (ingress)traffic.


SUMMARY STEPS

1. enable



4. ip flow monitor monitor-name {input | output}

5. end

6. show flow monitor monitor-name


DETAILED STEPS


Step 1 enable

Example:

Router> enable



Applying an IPv4 Flow Monitor to an Interface How to Configure a Predefined Record for the Flow Monitor




Example:




Example:


Specifies an interface and enters interface configuration mode.

Step 4 ip flow monitor monitor-name {input | output}

Example:

Router(config-if)# ip flow monitor FLOW-MONITOR-1 input

Activates the flow monitor that you created previously byassigning it to the interface to analyze traffic.

• You can configure input and output traffic analysisconcurrently by configuring the ip flow monitor monitor-name input and ip flow monitor monitor-name outputcommands on the same interface. You can use differentflow monitors for input and output traffic analysis.

Step 5 end

Example:


Exits interface configuration mode and returns to privilegedEXEC mode.

Step 6 show flow monitor monitor-name

Example:

Router# show flow monitor FLOW_MONITOR-1

(Optional) Displays the current status of the specified flowmonitor.

Step 7 show flow monitor [[name] monitor-name [cache[format {csv | record | table}]][statistics]]

Example:

Router# show flow monitor FLOW-MONITOR-1

(Optional) Displays the status and statistics for a FlexibleNetFlow flow monitor.

Applying an IPv6 Flow Monitor to an InterfaceBefore it can be activated, an IPv6 flow monitor must be applied to at least one interface. To activate anIPv4 flow monitor by applying the flow monitor to an interface, perform the following required task.

Applying an IPv6 Flow Monitor to an InterfaceHow to Configure a Predefined Record for the Flow Monitor


Note When you specify the "NetFlow IPv6 original input" predefined record for the flow monitor to emulateoriginal NetFlow, the flow monitor can be used only for analyzing input (ingress) traffic.

When you specify the "NetFlow IPv6 original output" predefined record for the flow monitor to emulatethe Egress NetFlow Accounting feature, the flow monitor can be used only for analyzing output (egress)traffic.

SUMMARY STEPS

1. enable



4. ipv6 flow monitor monitor-name {input | output}

5. end

6. show flow monitor monitor-name


DETAILED STEPS


Step 1 enable

Example:

Router> enable




Example:




Example:


Specifies an interface and enters interface configuration mode.

Step 4 ipv6 flow monitor monitor-name {input | output}

Example:

Router(config-if)# ipv6 flow monitor FLOW-MONITOR-2 input

Activates the flow monitor that you created previously byassigning it to the interface to analyze traffic.

• You can configure input and output traffic analysisconcurrently by configuring the ipv6 flow monitor monitor-name input and ipv6 flow monitor monitor-name outputcommands on the same interface. You can use different flowmonitors for input and output traffic analysis.

Configuring Cisco IOS Flexible NetFlow with Predefined Records How to Configure a Predefined Record for the Flow Monitor



Step 5 end

Example:


Exits interface configuration mode and returns to privilegedEXEC mode.

Step 6 show flow monitor monitor-name

Example:


(Optional) Displays the current status of the specified flowmonitor.


Example:


(Optional) Displays the configuration of the specified flowmonitor.

Configuration Examples for Flexible NetFlow with PredefinedRecords

• Example: Configuring a Flexible NetFlow Predefined Record for IPv4 Traffic, page 67• Example: Configuring a Flexible NetFlow Predefined Record for IPv6 Traffic, page 67

Example: Configuring a Flexible NetFlow Predefined Record for IPv4 TrafficThe following example shows how to configure a flow monitor using the Flexible NetFlow "BGP ToSnext-hop" predefined record to monitor IPv4 traffic.


!flow monitor FLOW-MONITOR-1 record netflow ipv4 bgp-nexthop-tos exit!ip cef!interface Ethernet 0/0 ip address 172.16.6.2 255.255.255.0 ip flow monitor FLOW-MONITOR-1 input!

Example: Configuring a Flexible NetFlow Predefined Record for IPv6 TrafficThe following example shows how to configure a flow monitor using the Flexible NetFlow "source prefix"predefined record to monitor IPv6 traffic.

Example: Configuring a Flexible NetFlow Predefined Record for IPv4 TrafficConfiguration Examples for Flexible NetFlow with Predefined Records



!flow monitor FLOW-MONITOR-2 record netflow ipv6 source-prefix exitip cefipv6 cef!interface Ethernet 0/0 ipv6 address 2001:DB8:2:ABCD::2/48 ipv6 flow monitor FLOW-MONITOR-2 input!

Where to Go NextFor information on advanced Flexible NetFlow configurations for specific purposes such as quality ofservice (QoS) and bandwidth monitoring, application and user flow monitoring and profiling, and securityanalysis, refer to the "Customizing Cisco IOS Flexible NetFlow Flow Records and Flow Monitors"module.


If you want to configure data export for Flexible NetFlow, refer to the "Configuring Data Export for CiscoIOS Flexible NetFlow with Flow Exporters" module.













Configuring Cisco IOS Flexible NetFlow with Predefined Records Where to Go Next







Standards

Standard Title

None --

MIBs

MIB MIBs Link



RFCs

RFC Title



Description Link



Feature Information for Flexible NetFlowThe following table provides release information about the feature or features described in this module.This table lists only the software release that introduced support for a given feature in a given softwarerelease train. Unless noted otherwise, subsequent releases of that software release train also support thatfeature.

Configuring Cisco IOS Flexible NetFlow with Predefined RecordsFeature Information for Flexible NetFlow






Configuring Cisco IOS Flexible NetFlow with Predefined Records Feature Information for Flexible NetFlow






12.2(50)SY

12.4(9)T

15.0(1)SY

15.0(1)SY1



The following commands wereintroduced or modified:cache(Flexible NetFlow), clearflow exporter, clear flowmonitor, clear sampler, collectcounter, collect flow, collectinterface, collect ipv4, collectipv4 destination, collect ipv4fragmentation, collect ipv4section, collect ipv4 source,collect ipv4 total-length, collectipv4 ttl, collect routing, collecttimestamp sys-uptime, collecttransport, collect transporticmp ipv4, collect transport tcp,collect transport udp, debugflow exporter, debug flowmonitor, debug flow record,debug sampler, description(Flexible NetFlow), destination,dscp (Flexible NetFlow),exporter, flow exporter, flowmonitor, flow platform, flowrecord, ip flow monitor, matchflow, match interface (FlexibleNetFlow), match ipv4, matchipv4 destination, match ipv4fragmentation, match ipv4section, match ipv4 source,match ipv4 total-length, matchipv4 ttl, match routing, matchtransport, match transporticmp ipv4, match transport tcp,match transport udp, mode(Flexible NetFlow), option(Flexible NetFlow), record,sampler, show flow exporter,show flow interface, show flowmonitor, show flow record,show sampler, source (Flexible

Configuring Cisco IOS Flexible NetFlow with Predefined RecordsFeature Information for Flexible NetFlow



NetFlow), statistics packet,template data timeout,transport (Flexible NetFlow).


12.2(33)SRE

12.2(50)SY

12.4(20)T

15.0(1)SY

15.0(1)SY1


Support for this feature wasadded for Cisco 7200 and 7300Network Processing Engine(NPE) series routers in Cisco IOSRelease 12.2(33)SRE.




Configuring Cisco IOS Flexible NetFlow with Predefined Records



Configuring Data Export for Flexible NetFlowwith Flow Exporters

This document contains information about and instructions for configuring flow exporters to exportFlexible NetFlow data to remote systems such as a UNIX server running NetFlow collector.

NetFlow is a Cisco IOS technology that provides statistics on packets flowing through the router. NetFlowis the standard for acquiring IP operational data from IP networks. NetFlow provides data to supportnetwork and security monitoring, network planning, traffic analysis, and IP accounting.


• Finding Feature Information, page 73• Prerequisites for Data Export for Flexible NetFlow with Flow Exporters, page 73• Restrictions for Data Export for Flexible NetFlow with Flow Exporters, page 74• Information About Data Export for Flexible NetFlow with Flow Exporters, page 74• How to Configure Data Export for Flexible NetFlow with Flow Exporters, page 75• Configuration Examples for Flexible NetFlow Data Export with Flow Exporters, page 81• Where to Go Next, page 83• Additional References, page 83• Feature Information for Flexible NetFlow, page 85



Prerequisites for Data Export for Flexible NetFlow with FlowExporters

• You are familiar with the information in the "Cisco IOS Flexible NetFlow Overview" module.




• The networking device must be running a Cisco IOS or Cisco IOS XE release that supports FlexibleNetFlow.

IPv4 Traffic



IPv6 Traffic


enable Flexible NetFlow: Cisco Express Forwarding IPv6 or distributed Cisco Express Forwarding.

Restrictions for Data Export for Flexible NetFlow with FlowExporters

• The NetFlow Version 5 export protocol that was first shipped in Cisco IOS Release 12.4(22)T issupported for flow monitors that use only the following Flexible NetFlow predefined records: netflow-original, original input, and original output.

Information About Data Export for Flexible NetFlow with FlowExporters

• Flow Exporters, page 74• Benefits of Flexible NetFlow Flow Exporters, page 74

Flow ExportersFlow exporters are created as separate components in a router’s configuration. Exporters are assigned toflow monitors to export the data from the flow monitor cache to a remote system such as a NetFlowcollector. Flow monitors can support more than one exporter. Each exporter can be customized to meet therequirements of the flow monitor or monitors in which it is used and the NetFlow collector systems towhich it is exporting data.

Benefits of Flexible NetFlow Flow ExportersFlexible NetFlow allows you to configure many different flow exporters, depending on your requirements.Some of the benefits of Flexible NetFlow flow exporters are as follows:

• Using flow exporters, you can create an exporter for every type of traffic that you want to analyze sothat you can send each type of traffic to a different NetFlow collector. Original NetFlow sends the datain a cache for all of the analyzed traffic to a maximum of two export destinations.

Flow Exporters Restrictions for Data Export for Flexible NetFlow with Flow Exporters


• Flow exporters support up to ten exporters per flow monitor. Original NetFlow is limited to only twoexport destinations per cache.

• Flow exporters can use both TCP and UDP for export.• Depending on your release, flow exporters can use class of service (CoS) in the packets that are sent to

export destinations to help ensure that the packets are given the correct priority throughout thenetwork. Original NetFlow exporters do not use CoS in the packets that are sent to export destinations.

• Depending on your release, flow exporter traffic can be encrypted.

How to Configure Data Export for Flexible NetFlow with FlowExporters

The tasks in this section explain how to export the data that is collected by Flexible NetFlow to a remotesystem for further analysis and storage.

Flow exporters are used to send the data that you collect with Flexible NetFlow to a remote system such asa NetFlow collector. Flow exporters use UDP as the transport protocol.

• Restrictions, page 75• Configuring the Flow Exporter, page 75• Configuring and Enabling Flexible NetFlow with Data Export, page 79

RestrictionsEach flow exporter supports only one destination. If you want to export the data to multiple destinations,you must configure multiple flow exporters and assign them to the flow monitor. Flow exporters are addedto flow monitors to enable data export from the flow monitor cache.

Note Only the keywords and arguments required for the Flexible NetFlow commands used in these tasks areexplained in these tasks. For information about the other keywords and arguments available for theseFlexible NetFlow commands, refer to the Cisco IOS Flexible NetFlow Command Reference .

Configuring the Flow ExporterTo configure the flow exporter, perform the following required task.

Note Each flow exporter supports only one destination. If you want to export the data to multiple destinations,you must configure multiple flow exporters and assign them to the flow monitor.

You can export to a destination using either an IPv4 or IPv6 address.

RestrictionsHow to Configure Data Export for Flexible NetFlow with Flow Exporters


SUMMARY STEPS

1. enable


3. flow exporter exporter-name


5. destination {ip-address | hostname} [vrf vrf-name]

6. export-protocol {netflow-v5 | netflow-v9 | ipfix}

7. dscp dscp

8. source interface-type interface-number

9. option {exporter-stats | interface-table | sampler-table| vrf-table} [timeout seconds]

10. output-features

11. template data timeout seconds

12. transport udp udp-port

13. ttl seconds

14. end

15. show flow exporter exporter-name

16. show running-config flow exporter exporter-name

DETAILED STEPS


Step 1 enable

Example:

Device> enable




Example:



Step 3 flow exporter exporter-name

Example:

Device(config)# flow exporter EXPORTER-1

Creates the flow exporter and enters Flexible NetFlow flowexporter configuration mode.

• This command also allows you to modify an existing flowexporter.

Configuring Data Export for Flexible NetFlow with Flow Exporters How to Configure Data Export for Flexible NetFlow with Flow Exporters




Example:

Device(config-flow-exporter)# description Exports to the datacenter

(Optional) Configures a description to the exporter that will appearin the configuration and the display of the show flow exportercommand.

Step 5 destination {ip-address | hostname} [vrf vrf-name]

Example:

Device(config-flow-exporter)# destination 172.16.10.2

Specifies the IP address or hostname of the destination system forthe exporter.

Note You can export to a destination using either an IPv4 or IPv6address.

Step 6 export-protocol {netflow-v5 | netflow-v9 | ipfix}

Example:

Device(config-flow-exporter)# export-protocol netflow-v9

Specifies the version of the NetFlow export protocol used by theexporter. The export of extracted fields from NBAR is supportedonly over IPFIX.

• Default: netflow-v9.

Step 7 dscp dscp

Example:

Device(config-flow-exporter)# dscp 63

(Optional) Configures differentiated services code point (DSCP)parameters for datagrams sent by the exporter.

• The range for the dscp argument is from 0 to 63. Default: 0.

Step 8 source interface-type interface-number

Example:

Device(config-flow-exporter)# source ethernet 0/0

(Optional) Specifies the local interface from which the exporterwill use the IP address as the source IP address for exporteddatagrams.

Step 9 option {exporter-stats | interface-table | sampler-table| vrf-table} [timeout seconds]

Example:

Device(config-flow-exporter)# option exporter-stats timeout 120

(Optional) Configures options data parameters for the exporter.

• You can configure all three options concurrently.• The range for the seconds argument is 1 to 86,400. Default:

600.

Configuring Data Export for Flexible NetFlow with Flow ExportersHow to Configure Data Export for Flexible NetFlow with Flow Exporters



Step 10 output-features

Example:

Device(config-flow-exporter)# output-features

(Optional) Enables sending export packets using quality of service(QoS) and encryption.

Step 11 template data timeout seconds

Example:

Device(config-flow-exporter)# template data timeout 120

(Optional) Configure resending of templates based on a timeout.

• The range for the seconds argument is 1 to 86400 (86400seconds = 24 hours).

Step 12 transport udp udp-port

Example:

Device(config-flow-exporter)# transport udp 650

Specifies the UDP port on which the destination system is listeningfor exported datagrams.

• The range for the udp-port argument is from 1 to 65536.

Step 13 ttl seconds

Example:

Device(config-flow-exporter)# ttl 15

(Optional) Configures the time-to-live (TTL) value for datagramssent by the exporter.

• The range for the seconds argument is from 1 to 255.

Step 14 end

Example:

Device(config-flow-exporter)# end

Exits flow exporter configuration mode and returns to privilegedEXEC mode.

Step 15 show flow exporter exporter-name

Example:

Device# show flow exporter FLOW_EXPORTER-1

(Optional) Displays the current status of the specified flowexporter.

Step 16 show running-config flow exporter exporter-name

Example:

Device# show running-config flow exporter FLOW_EXPORTER-1

(Optional) Displays the configuration of the specified flowexporter.



Configuring and Enabling Flexible NetFlow with Data ExportYou must create a flow monitor to configure the types of traffic for which you want to export the cachedata. You must enable the flow monitor by applying it to at least one interface to start exporting data. Toconfigure and enable Flexible NetFlow with data export, perform this required task.


Note You must remove a flow monitor from all of the interfaces to which you have applied it before you canmodify the record format of the flow monitor.

When you specify the "NetFlow original," or the "NetFlow IPv4 original input," or the "NetFlow IPv6original input" predefined record for the flow monitor to emulate original NetFlow, the flow monitor can beused only for analyzing input (ingress) traffic.

When you specify the "NetFlow IPv4 original output" or the "NetFlow IPv6 original output" predefinedrecord for the flow monitor to emulate the Egress NetFlow Accounting feature, the flow monitor can beused only for analyzing output (egress) traffic.

SUMMARY STEPS

1. enable



4. record {record-name | netflow-original | netflow {ipv4 | ipv6 record [peer] }]


6. exit


8. {ip | ipv6} flow monitor monitor-name {input | output}

9. end


DETAILED STEPS


Step 1 enable

Example:

Device> enable



Configuring and Enabling Flexible NetFlow with Data ExportHow to Configure Data Export for Flexible NetFlow with Flow Exporters




Example:




Example:


Creates a flow monitor and enters Flexible NetFlow flowmonitor configuration mode.


Step 4 record {record-name | netflow-original | netflow {ipv4 |ipv6 record [peer] }]

Example:




Example:


Specifies the name of an exporter that you createdpreviously.

Step 6 exit

Example:

Device(config-flow-monitor)# exit

Exits Flexible NetFlow flow monitor configuration modeand returns to global configuration mode.


Example:

Device(config)# interface ethernet 0/0


Step 8 {ip | ipv6} flow monitor monitor-name {input | output}

Example:

Device(config-if)# ip flow monitor FLOW-MONITOR-1 input





Step 9 end

Example:

Device(config-if)# end


Step 10 show flow monitor [[name] monitor-name [cache [format{csv | record | table}]][statistics]]

Example:


(Optional) Displays the status and statistics for a FlexibleNetFlow flow monitor. This will verify data export isenabled for the flow monitor cache.

Configuration Examples for Flexible NetFlow Data Exportwith Flow Exporters

• Example: Configuring Multiple Export Destinations, page 81• Example: Configuring Sending Export Packets Using QoS, page 82• Example: Configuring Version 5 Export, page 83

Example: Configuring Multiple Export DestinationsThe following example shows how to configure multiple export destinations for Flexible NetFlow for IPv4and IPv6 traffic.


!flow exporter EXPORTER-1 destination 172.16.10.2 transport udp 90 exit!flow exporter EXPORTER-2 destination 172.16.10.3 transport udp 90 exit!flow monitor FLOW-MONITOR-1 record netflow ipv4 original-input exporter EXPORTER-2 exporter EXPORTER-1!!flow monitor FLOW-MONITOR-2 record netflow ipv6 original-input exporter EXPORTER-2 exporter EXPORTER-1!ip cef!

Example: Configuring Multiple Export DestinationsConfiguration Examples for Flexible NetFlow Data Export with Flow Exporters


interface Ethernet 0/0 ip address 172.16.6.2 255.255.255.0 ipv6 address 2001:DB8:2:ABCD::2/48 ip flow monitor FLOW-MONITOR-1 input ipv6 flow monitor FLOW-MONITOR-2 input!

The following display output shows that the flow monitor is exporting data to the two exporters:

Device# show flow monitor FLOW-MONITOR-1Flow Monitor FLOW-MONITOR-1: Description: User defined Flow Record: netflow original-input Flow Exporter: EXPORTER-1 EXPORTER-2 Cache: Type: normal Status: allocated Size: 4096 entries / 311316 bytes Inactive Timeout: 15 secs Active Timeout: 1800 secs Update Timeout: 1800 secs

Example: Configuring Sending Export Packets Using QoSThe following example shows how to enable QoS on Flexible Netflow export packets.

Note The Flexible NetFlow export packets are transmitted using QoS on Ethernet interface 0/1 (the interface onwhich the destination is reachable) to the destination host (IP address 10.0.1.2).


!flow record FLOW-RECORD-1 match ipv4 source address collect counter packets!flow exporter FLOW-EXPORTER-1 destination 10.0.1.2 output-features dscp 18!flow monitor FLOW-MONITOR-1 record FLOW-RECORD-1 exporter FLOW-EXPORTER-1 cache entries 1024!ip cef!class-map match-any COS3!policy-map PH_LABS_FRL_64k_16k_16k_8k_8k class COS3 bandwidth percent 2 random-detect dscp-based random-detect exponential-weighting-constant 1 random-detect dscp 18 200 300 10!interface Ethernet 0/0 ip address 10.0.0.1 255.255.255.0 ip flow monitor FLOW-MONITOR-1 input!interface Ethernet 0/1 ip address 10.0.1.1 255.255.255.0 service-policy output PH_LABS_FRL_64k_16k_16k_8k_8k!

Example: Configuring Sending Export Packets Using QoS Configuration Examples for Flexible NetFlow Data Export with Flow Exporters


The following display output shows that the flow monitor is exporting data using output feature supportthat enables the exported data to use QoS:

Device# show flow monitor FLOW-MONITOR-1Flow Exporter FLOW-EXPORTER-1: Description: User defined Tranport Configuration: Destination IP address: 10.0.1.2 Source IP address: 10.0.0.1 Transport Protocol: UDP Destination Port: 9995 Source Port: 56750 DSCP: 0x12 TTL: 255 Output Features: Used

Example: Configuring Version 5 ExportThe following example shows how to configure version 5 export for Flexible NetFlow.


!flow exporter EXPORTER-1 destination 172.16.10.2 export-protocol netflow-v5 transport udp 90 exit!flow monitor FLOW-MONITOR-1 record netflow ipv4 original-input exporter EXPORTER-1!ip cef!interface Ethernet 0/0 ip address 172.16.6.2 255.255.255.0 ip flow monitor FLOW-MONITOR-1 input!

Where to Go NextFor information on advanced Flexible NetFlow configurations for specific purposes such as QoS andbandwidth monitoring, application and user flow monitoring and profiling, and security analysis, refer tothe "Customizing Cisco IOS Flexible NetFlow Flow Records and Flow Monitors" module.


If you want to configure any of the predefined records for Flexible NetFlow, refer to the "ConfiguringCisco IOS Flexible NetFlow with Predefined Records" module.

Additional References

Example: Configuring Version 5 ExportWhere to Go Next


Related Documents















Standards

Standard Title

None --

MIBs

MIB MIBs Link



RFCs

RFC Title


Configuring Data Export for Flexible NetFlow with Flow Exporters Additional References





Description Link





Configuring Data Export for Flexible NetFlow with Flow ExportersFeature Information for Flexible NetFlow








12.2(50)SY

12.4(9)T

15.0(1)SY

15.0(1)SY1




Configuring Data Export for Flexible NetFlow with Flow Exporters Feature Information for Flexible NetFlow





12.2(33)SRC

12.2(50)SY

12.4(9)T

15.0(1)SY

15.0(1)SY1



The following commands wereintroduced or modified: collectrouting, debug flow record,collect ipv4, collect ipv4destination, collect ipv4fragmentation, collect ipv4section, collect ipv4 source, ipflow monitor, match ipv4,match ipv4 destination, matchipv4 fragmentation, match ipv4section, match ipv4 source,match routing, record, showflow monitor, show flow record.

Flexible NetFlow--NetFlow v9Export Format

12.2(33)SRE

12.2(50)SY

12.4(9)T

15.0(1)SY

15.0(1)SY1

Enables sending export packetsusing the Version 9 exportformat.


No commands were introduced ormodified by this feature.

Configuring Data Export for Flexible NetFlow with Flow ExportersFeature Information for Flexible NetFlow




12.2(33)SRE

12.2(50)SY

12.4(20)T

15.0(1)SY

15.0(1)SY1




Flexible NetFlow--OutputFeatures on Data Export

12.4(20)T Enables sending export packetsusing QoS and encryption.

The following command wasintroduced: output-features.

Flexible NetFlow--NetFlow V5Export Protocol

12.2(33)SRE

12.2(50)SY

12.4(22)T

15.0(1)SY

15.0(1)SY1

Enables sending export packetsusing the Version 5 exportprotocol.



Configuring Data Export for Flexible NetFlow with Flow Exporters Feature Information for Flexible NetFlow



Flexible NetFlow: Export to anIPv6 Address

15.2(2)T This feature enables FlexibleNetFlow to export data to adestination using an IPv6 address.

The following commands wereintroduced or modified:destination

Flexible NetFlow: IPFIX ExportFormat

15.2(4)M Enables sending export packetsusing the IPFIX export protocol.The export of extracted fieldsfrom NBAR is only supportedover IPFIX.

Support for this feature wasadded for Cisco ASR 1000 SeriesAggregation Services routers inCisco IOS XE Release 3.7S.




Configuring Data Export for Flexible NetFlow with Flow Exporters



Example: Configuring Version 5 Export


Customizing Flexible NetFlow Flow Recordsand Flow Monitors

This document contains information about and instructions for customizing Cisco IOS Flexible NetFlowflow records and flow monitors. If the tasks and configuration examples in the "Getting Started withConfiguring Cisco IOS Flexible NetFlow" module and the "Configuring Cisco IOS Flexible NetFlow withPredefined Records" module were not suitable for your traffic analysis requirements, you can use theinformation and instructions in this document to customize Flexible NetFlow to meet your traffic analysisrequirements.

NetFlow is a Cisco IOS technology that provides statistics on packets flowing through a router. NetFlowis the standard for acquiring IP operational data from IP networks. NetFlow provides data to supportnetwork and security monitoring, network planning, traffic analysis, and IP accounting.


• Finding Feature Information, page 91• Prerequisites for Customizing Flexible NetFlow Flow Records and Flow Monitors, page 92• Information About Customizing Flexible NetFlow Flow Records and Flow Monitors, page 92• How to Customize Flexible NetFlow Flow Records and Flow Monitors, page 93• Configuration Examples for Customizing Flow Records and Flow Monitors, page 100• Where to Go Next, page 104• Additional References, page 104• Feature Information for Flexible NetFlow, page 105






Prerequisites for Customizing Flexible NetFlow Flow Recordsand Flow Monitors

• You are familiar with the information in the " Cisco IOS Flexible NetFlow Overview " module.• You are familiar with the Flexible NetFlow key fields as they are defined in the following commands

in the Cisco IOS Flexible NetFlow Command Reference :

◦ match flow◦ match interface◦ match {ipv4 | ipv6}◦ match routing◦ match transport

• You are familiar with the Flexible NetFlow nonkey fields as they are defined in the followingcommands in the Cisco IOS Flexible NetFlow Command Reference :

◦ collect counter◦ collect flow◦ collect interface◦ collect{ipv4 | ipv6}◦ collect routing◦ collect timestamp sys-uptime◦ collect transport

• The networking device must be running a Cisco IOS release that supports Flexible NetFlow.

IPv4 Traffic



IPv6 Traffic


enable Flexible NetFlow: Cisco Express Forwarding IPv6 or distributed Cisco Express Forwarding.

Information About Customizing Flexible NetFlow FlowRecords and Flow Monitors

• Criteria for Identifying Traffic To Be Used in Analysis in Flexible NetFlow, page 92

Criteria for Identifying Traffic To Be Used in Analysis in Flexible NetFlowIf the predefined Flexible NetFlow records are not suitable for your traffic requirements, you can create auser-defined (custom) record using the Flexible NetFlow collect and match commands. Before you can

Criteria for Identifying Traffic To Be Used in Analysis in Flexible NetFlow Prerequisites for Customizing Flexible NetFlow Flow Records and Flow Monitors


create a customized record, you must decide the criteria that you are going to use for the key and nonkeyfields.

If you want to create a customized record for detecting network attacks, you must include the appropriatekey and nonkey fields in the record to ensure that the router creates the flows and captures the data that youneed to analyze the attack and respond to it. For example, SYN flood attacks are a common denial ofservice (DoS) attack in which TCP flags are used to flood open TCP requests to a destination host. When anormal TCP connection starts, a destination host receives a SYN (synchronize/start) packet from a sourcehost and sends back a SYN ACK (synchronize acknowledge). The destination host must then hear an ACK(acknowledge) of the SYN ACK before the connection is established. This is referred to as the "TCP three-way handshake." While the destination host waits for the ACK to the SYN ACK, a connection queue offinite size on the destination host keeps track of connections waiting to be completed. This queue typicallyempties quickly because the ACK is expected to arrive a few milliseconds after the SYN ACK. The TCPSYN attack exploits this design by having an attacking source host generate TCP SYN packets withrandom source addresses toward a victim host. The victim destination host sends a SYN ACK back to therandom source address and adds an entry to the connection queue. Because the SYN ACK is destined foran incorrect or nonexistent host, the last part of the TCP three-way handshake is never completed and theentry remains in the connection queue until a timer expires, typically for about one minute. Rapidgeneration by the source of TCP SYN packets from random IP addresses can fill the connection queue andcause denial of TCP services (such as e-mail, file transfer, or WWW) to legitimate users.

The information needed for a security monitoring record for this type of DoS attack might include thefollowing key and nonkey fields:

• Key fields:

◦ Destination IP address or destination IP subnet◦ TCP flags◦ Packet count

• Nonkey fields

◦ Destination IP address◦ Source IP address◦ Interface input and output

Tip Many users configure a general Flexible NetFlow monitor that triggers a more detailed Flexible NetFlowview of a DoS attack using these key and nonkey fields.

How to Customize Flexible NetFlow Flow Records and FlowMonitors

Note Only the keywords and arguments required for the Flexible NetFlow commands used in these tasks areexplained in these tasks. For information about the other keywords and arguments available for theseFlexible NetFlow commands, refer to the Cisco IOS Flexible NetFlow Command Reference.

• Configuring a Customized Flow Record, page 94

Customizing Flexible NetFlow Flow Records and Flow MonitorsHow to Customize Flexible NetFlow Flow Records and Flow Monitors


• Creating a Customized Flow Monitor, page 96• Applying a Flow Monitor to an Interface, page 98

Configuring a Customized Flow RecordCustomized flow records are used to analyze traffic data for a specific purpose. A customized flow recordmust have at least one match criterion for use as the key field and typically has at least one collect criterionfor use as a nonkey field.

There are hundreds of possible permutations of customized flow records. This task explains the steps thatare used to create one of the possible permutations. Modify the steps in these tasks as appropriate to createa customized flow record for your requirements.

To configure a customized flow record, perform the following task.

SUMMARY STEPS

1. enable


3. flow record record-name


5. match {ipv4 | ipv6}{destination | source} address

6. Repeat Step 5 as required to configure additional key fields for the record.

7. collect interface {input | output}

8. Repeat Step 7 as required to configure additional nonkey fields for the record.

9. end



DETAILED STEPS


Step 1 enable

Example:

Device> enable




Example:



Configuring a Customized Flow Record How to Customize Flexible NetFlow Flow Records and Flow Monitors



Step 3 flow record record-name

Example:

Device(config)# flow record FLOW-RECORD-1

Creates a flow record and enters Flexible NetFlow flow recordconfiguration mode.

• This command also allows you to modify an existingflow record.


Example:

Device(config-flow-record)# description Used for basic traffic analysis

(Optional) Creates a description for the flow record.

Step 5 match {ipv4 | ipv6}{destination | source} address

Example:

Device(config-flow-record)# match ipv4 destination address

Configures a key field for the flow record.

Note This example configures the IPv4 destination address asa key field for the record. For information about theother key fields available for the match ipv4 command,and the other match commands that are available toconfigure key fields, refer to the Cisco IOS FlexibleNetFlow Command Reference .

Step 6 Repeat Step 5 as required to configure additional keyfields for the record.

--

Step 7 collect interface {input | output}

Example:

Device(config-flow-record)# collect interface input

Configures the input interface as a nonkey field for the record.

Note This example configures the input interface as a nonkeyfield for the record. For information on the other collectcommands that are available to configure nonkey fields,refer to the Cisco IOS Flexible NetFlow CommandReference .

Step 8 Repeat Step 7 as required to configure additional nonkeyfields for the record.

--

Step 9 end

Example:

Device(config-flow-record)# end

Exits Flexible NetFlow flow record configuration mode andreturns to privileged EXEC mode.


Example:

Device# show flow record FLOW_RECORD-1

(Optional) Displays the current status of the specified flowrecord.





Example:

Device# show running-config flow record FLOW_RECORD-1

(Optional) Displays the configuration of the specified flowrecord.

Creating a Customized Flow MonitorTo create a customized flow monitor, perform the following required task.

Each flow monitor has a separate cache assigned to it. Each flow monitor requires a record to define thecontents and layout of its cache entries.

If you want to use a customized record instead of using one of the Flexible NetFlow predefined records,you must create the customized record before you can perform this task.

If you want to add a flow exporter to the flow monitor for data export, you must create the exporter beforeyou can complete this task.

Note You must use the no ip flow monitor command to remove a flow monitor from all of the interfaces towhich you have applied it before you can modify the parameters for the record command on the flowmonitor. For information about the ip flow monitor command, refer to the Cisco IOS Flexible NetFlowCommand Reference.

SUMMARY STEPS

1. enable




5. record {record-name | netflow-original | netflow {ipv4 | ipv6} record [peer]}

6. cache {entries number | timeout {active |inactive|update} seconds | type {immediate | normal |permanent}}

7. Repeat Step 6 as required to finish modifying the cache parameters for this flow monitor.

8. statistics packet protocol

9. statistics packet size


11. end



Creating a Customized Flow Monitor How to Customize Flexible NetFlow Flow Records and Flow Monitors


DETAILED STEPS


Step 1 enable

Example:

Device> enable




Example:




Example:





Example:

Device(config-flow-monitor)# description Used for basic ipv4 traffic analysis


Step 5 record {record-name | netflow-original | netflow {ipv4 |ipv6} record [peer]}

Example:

Device(config-flow-monitor)# record FLOW-RECORD-1


Step 6 cache {entries number | timeout {active |inactive|update}seconds | type {immediate | normal | permanent}}

Example:

Device(config-flow-monitor)# cache type normal

(Optional) Modifies the flow monitor cache parameterssuch as timeout values, number of cache entries, and thecache type.

• The values for the keywords associated with thetimeout keyword have no effect when the cachetype is set to immediate.

Step 7 Repeat Step 6 as required to finish modifying the cacheparameters for this flow monitor.

--




Step 8 statistics packet protocol

Example:

Device(config-flow-monitor)# statistics packet protocol

(Optional) Enables the collection of protocoldistribution statistics for Flexible NetFlow monitors.

Step 9 statistics packet size

Example:

Device(config-flow-monitor)# statistics packet size

(Optional) Enables the collection of size distributionstatistics for Flexible NetFlow monitors.


Example:


(Optional) Specifies the name of an exporter that wascreated previously.

Step 11 end

Example:



Step 12 show flow monitor [[name] monitor-name [cache [format{csv | record | table}]][statistics]]

Example:


(Optional) Displays the status and statistics for aFlexible NetFlow flow monitor.


Example:

Device# show running-config flow monitor FLOW_MONITOR-1

(Optional) Displays the configuration of the specifiedflow monitor.

Applying a Flow Monitor to an InterfaceBefore it can be activated, a flow monitor must be applied to at least one interface. To activate a flowmonitor, perform the following required task.

Applying a Flow Monitor to an Interface How to Customize Flexible NetFlow Flow Records and Flow Monitors


SUMMARY STEPS

1. enable



4. {ip | ipv6} flow monitor monitor-name {input | output}

5. Repeat Steps 3 and 4 to activate a flow monitor on any other interfaces in the device over which youwant to monitor traffic.

6. end



DETAILED STEPS


Step 1 enable

Example:

Device> enable




Example:




Example:

Device(config)# interface GigabitEthernet 0/0/0

Specifies an interface and enters interfaceconfiguration mode.

Step 4 {ip | ipv6} flow monitor monitor-name {input | output}

Example:

Device(config-if)# ip flow monitor FLOW-MONITOR-1 input

Activates a flow monitor that was createdpreviously by assigning it to the interface toanalyze traffic.

Step 5 Repeat Steps 3 and 4 to activate a flow monitor on any otherinterfaces in the device over which you want to monitor traffic.

--

Step 6 end

Example:







Example:

Device# show flow interface GigabitEthernet 0/0/0



Example:

Device# show flow monitor name FLOW_MONITOR-1 cache format record

Displays the status, statistics, and flow data in thecache for the specified flow monitor.

Configuration Examples for Customizing Flow Records andFlow Monitors

• Example: Configuring a Permanent Flow Record Cache with a Limited Number of Flows, page 100• Example: Configuring a Customized Flow Record Cache for Monitoring IPv6 Traffic, page 101• Example: Configuring Flexible NetFlow for Monitoring MAC and VLAN Statistics, page 102• Example: Configuring Flexible NetFlow for Ingress VRF Support, page 102• Example: Configuring Flexible NetFlow for Network-Based Application Recognition, page 103• Example: Configuring Flexible NetFlow for CTS Fields, page 103

Example: Configuring a Permanent Flow Record Cache with a LimitedNumber of Flows

The following example is designed to monitor the type of service (ToS) field usage on all interfaces in therouter. An exporter is not configured because this example is intended to be used to capture additional datafor analysis on the router using the show flow monitorcommand.


!ip cef!flow record QOS_RECORD description UD: Flow Record to monitor the use of TOS within this router/network match interface input match interface output match ipv4 tos collect counter packets collect counter bytes exit!flow monitor QOS_MONITOR description UD: Flow Monitor which watches the limited combinations of interface and TOS record QOS_RECORD cache type permanent

Example: Configuring a Permanent Flow Record Cache with a Limited Number of Flows Configuration Examples for Customizing Flow Records and Flow Monitors


cache entries 8192 ! 2^5 (combos of interfaces) * 256 (values of TOS) exit!interface ethernet0/0 ip flow monitor QOS_MONITOR input exit!interface ethernet0/1 ip flow monitor QOS_MONITOR input exit!interface ethernet0/2 ip flow monitor QOS_MONITOR input exit!interface serial2/0 ip flow monitor QOS_MONITOR input exit!interface serial2/1 ip flow monitor QOS_MONITOR input!

The display from the show flow monitor command shows the current status of the cache.

Router# show flow monitor QOS_MONITOR cache Cache type: Permanent Cache size: 8192 Current entries: 2 High Watermark: 2 Flows added: 2 Updates sent ( 1800 secs) 0

Example: Configuring a Customized Flow Record Cache for Monitoring IPv6Traffic

The following example creates a customized flow record cache for monitoring IPv6 traffic.


!ip cefipv6 cef!flow record FLOW-RECORD-2 description Used for basic IPv6 traffic analysis match ipv6 destination address collect counter bytes collect counter packets!flow monitor FLOW-MONITOR-2 description Used for basic IPv6 traffic analysis record FLOW-RECORD-2 cache entries 1000!interface GigabitEthernet0/0/0 ipv6 address 2001:DB8:2:ABCD::2/48 ipv6 flow monitor FLOW-MONITOR-2 input!interface GigabitEthernet1/0/0 ipv6 address 2001:DB8:3:ABCD::1/48 ipv6 flow monitor FLOW-MONITOR-2 output!

Example: Configuring a Customized Flow Record Cache for Monitoring IPv6 TrafficConfiguration Examples for Customizing Flow Records and Flow Monitors


Example: Configuring Flexible NetFlow for Monitoring MAC and VLANStatistics

The following example shows how to configure Flexible NetFlow for monitoring MAC and VLANstatistics.


! flow record LAYER-2-FIELDS-1 match ipv4 source address match ipv4 destination address match datalink dot1q vlan output match datalink mac source address input match datalink mac source address output match datalink mac destination address input match flow direction! exit!!flow monitor FLOW-MONITOR-4 record LAYER-2-FIELDS-1 exit!ip cef!interface GigabitEthernet0/0/1 ip address 172.16.6.2 255.255.255.0 ip flow monitor FLOW-MONITOR-1 input!

Example: Configuring Flexible NetFlow for Ingress VRF SupportThe following example configures the collection of the virtual routing and forwarding (VRF) ID fromincoming packets on a router by applying an input flow monitor having a flow record that collects the VRFID as a key field.


!flow record rm_1match routing vrf inputmatch ipv4 source addressmatch ipv4 destination addresscollect interface inputcollect interface outputcollect counter packets!flow monitor mm_1record rm_1!interface Serial2/0ip vrf forwarding greenip address 172.16.2.2 255.255.255.252ip flow monitor mm_1 output!end

Example: Configuring Flexible NetFlow for Monitoring MAC and VLAN Statistics Configuration Examples for Customizing Flow Records and Flow Monitors


Example: Configuring Flexible NetFlow for Network-Based ApplicationRecognition

The following example uses Network-based Application recognition (NBAR) to create different flows foreach application seen between any two IP hosts by applying a flow monitor having a flow record thatcollects the application name as a key field.


!flow record rm_1match application namematch ipv4 source addressmatch ipv4 destination addresscollect interface inputcollect interface outputcollect counter packets!flow monitor mm_1record rm_1!interface FastEthernet0/0ip address 172.16.2.2 255.255.255.0ip flow monitor mm_1 input!end

Example: Configuring Flexible NetFlow for CTS FieldsThis following example configures the collection of the Cisco TrustSec (CTS) fields, source SecurityGroup Tag (SGT) and destination Security Group Tag (DGT), in IPv4 traffic.


!flow exporter EXPORTER-1destination 172.16.10.2transport udp 90exitflow record rm_1match ipv4 protocolmatch ipv4 source addressmatch ipv4 destination addressmatch transport source-portmatch transport destination-portmatch flow directionmatch flow cts source group-tagmatch flow cts destination group-tagcollect routing source ascollect routing destination ascollect routing source as peercollect routing destination as peercollect routing next-hop address ipv4collect routing next-hop address ipv4 bgpcollect ipv4 source prefixcollect ipv4 source maskcollect ipv4 destination prefixcollect ipv4 destination maskcollect interface inputcollect interface outputcollect counter bytescollect counter packetscollect timestamp sys-uptime firstcollect timestamp sys-uptime last!

Example: Configuring Flexible NetFlow for Network-Based Application RecognitionConfiguration Examples for Customizing Flow Records and Flow Monitors


flow monitor mm_1record rm_1exporter EXPORTER-1!interface FastEthernet0/0ip address 172.16.2.2 255.255.255.0ip flow monitor mm_1 input!end

Where to Go NextIf you want to configure data export for Flexible NetFlow, refer to the "Configuring Data Export for CiscoIOS Flexible NetFlow with Flow Exporters" module.


If you want to configure any of the predefined records for Flexible NetFlow, refer to the "ConfiguringCisco IOS Flexible NetFlow with Predefined Records" module.





Flexible NetFlow Feature Roadmap "Cisco IOS Flexible NetFlow Features Roadmap"


Configuring flow exporters to export FlexibleNetFlow data.











Customizing Flexible NetFlow Flow Records and Flow Monitors Where to Go Next



Standards

Standard Title

None --

MIBs

MIB MIBs Link



RFCs

RFC Title



Description Link





Customizing Flexible NetFlow Flow Records and Flow MonitorsFeature Information for Flexible NetFlow









12.2(50)SY

12.4(9)T

15.0(1)SY

15.0(1)SY1




Customizing Flexible NetFlow Flow Records and Flow Monitors Feature Information for Flexible NetFlow





12.2(33)SRC

12.2(50)SY

12.4(9)T

15.0(1)SY

15.0(1)SY1



The following commands wereintroduced or modified: collectrouting, debug flow record,collect ipv4, collect ipv4destination, collect ipv4fragmentation, collect ipv4section, collect ipv4 source, ipflow monitor, match ipv4,match ipv4 destination, matchipv4 fragmentation, match ipv4section, match ipv4 source,match routing, record, showflow monitor, show flow record.

Flexible NetFlow--Layer 2 Fields 12.2(33)SRE

12.4(22)T

Enables collecting statistics forLayer 2 fields such as MACaddresses and virtual LAN(VLAN) IDs from traffic.


The following commands wereintroduced or modified:

collect datalink dot1q vlan ,collect datalink mac, matchdatalink dot1q vlan, matchdatalink mac.

Customizing Flexible NetFlow Flow Records and Flow MonitorsFeature Information for Flexible NetFlow




12.2(33)SRE

12.2(50)SY

12.4(20)T

15.0(1)SY

15.0(1)SY1




Flexible NetFlow--Ingress VRFSupport

12.2(33)SRE

12.2(50)SY

15.0(1)M

15.0(1)SY

15.0(1)SY1

Enables collecting the virtualrouting and forwarding (VRF) IDfrom incoming packets on arouter by applying an input flowmonitor having a flow record thatcollects the VRF ID as a key or anonkey field.


The following commands wereintroduced or modified: collectrouting, match routing, option(Flexible NetFlow), show flowmonitor.

Customizing Flexible NetFlow Flow Records and Flow Monitors Feature Information for Flexible NetFlow



Flexible NetFlow--NBARApplication Recognition

15.0(1)M Network-based Applicationrecognition (NBAR) enablescreation of different flows foreach application seen betweenany two IP hosts by applying aflow monitor having a flowrecord that collects theapplication name as a key or anonkey field.

The following commands wereintroduced or modified:

collect application name, matchapplication name, option(Flexible NetFlow), show flowmonitor.

TrustSec NetFlow IPv4 SGACLDeny and Drop Export

12.2(50)SY

15.0(1)SY

15.0(1)SY1

Enables Flexible NetFlow tocollect Cisco Trusted Security(CTS) information in IPv4 traffic.

The following commands wereintroduced or modified: collectflow, match flow, show flowmonitor.

TrustSec NetFlow IPv6 SGACLDeny and Drop ExportS

12.2(50)SY

15.0(1)SY

15.0(1)SY1

Enables Flexible NetFlow tocollect Cisco Trusted Security(CTS) information in IPv6 traffic.

The following commands wereintroduced or modified: collectflow, match flow, show flowmonitor.



Customizing Flexible NetFlow Flow Records and Flow Monitors



Example: Configuring Flexible NetFlow for CTS Fields


Using Flexible NetFlow Flow Sampling

This document contains information about and instructions for configuring sampling to reduce the CPUoverhead of analyzing traffic with Flexible NetFlow.

NetFlow is a Cisco technology that provides statistics on packets flowing through a router. NetFlow is thestandard for acquiring IP operational data from IP networks. NetFlow provides data to support networkand security monitoring, network planning, traffic analysis, and IP accounting.

Flexible NetFlow improves on original NetFlow by adding the capability to customize the traffic analysisparameters for your specific requirements. Flexible NetFlow faciltates the creation of more complexconfigurations for traffic analysis and data export through the use of reusable configuration components.

• Finding Feature Information, page 111• Prerequisites for Using Flow Sampling, page 111• Information About Flexible NetFlow Samplers, page 112• How to Configure Flexible NetFlow Flow Sampling, page 112• Configuration Examples for Using Flexible NetFlow Flow Sampling, page 116• Additional References, page 118• Feature Information for Flexible Netflow—Random Sampling, page 119



Prerequisites for Using Flow Sampling• The networking device must be running a Cisco release that supports Flexible NetFlow.

IPv4 Traffic






IPv6 Traffic



Information About Flexible NetFlow Samplers• Flow Samplers, page 112

Flow SamplersFlow samplers are created as separate components in a router’s configuration. Flow samplers are used toreduce the load on the device that is running Flexible NetFlow by limiting the number of packets that areselected for analysis.

Flow sampling exchanges monitoring accuracy for router performance. When you apply a sampler to aflow monitor, the overhead load on the router of running the flow monitor is reduced because the numberof packets that the flow monitor must analyze is reduced. The reduction in the number of packets that areanalyzed by the flow monitor causes a corresponding reduction in the accuracy of the information stored inthe flow monitor’s cache.

Samplers are combined with flow monitors when they are applied to an interface with the ip flow monitorcommand.

How to Configure Flexible NetFlow Flow SamplingFlow sampling reduces the CPU overhead of analyzing traffic with Flexible NetFlow by reducing thenumber of packets that are analyzed.

Note Only the keywords and arguments required for the Flexible NetFlow commands used in these tasks areexplained in these tasks. For information about the other keywords and arguments available for theseFlexible NetFlow commands, refer to the Cisco IOS Flexible NetFlow Command Reference .

• Configuring a Flow Monitor, page 112• Configuring and Enabling Flow Sampling, page 114

Configuring a Flow MonitorSamplers are applied to an interface in conjunction with a flow monitor. You must create a flow monitor toconfigure the types of traffic that you want to analyze before you can enable sampling. To configure a flowmonitor, perform the following required task.


Flow Samplers Information About Flexible NetFlow Samplers


Note You must use the no ip flow monitorcommand to remove a flow monitor from all of the interfaces towhich you have applied it before you can modify the parameters for the record command on the flowmonitor.

SUMMARY STEPS

1. enable




5. record {record-name | netflow-original | netflow {ipv4 | ipv6} record [peer]}

6. end

DETAILED STEPS


Step 1 enable

Example:

Device> enable




Example:




Example:





Example:

Device(config-flow-monitor)# description Used for basic traffic analysis


Using Flexible NetFlow Flow SamplingHow to Configure Flexible NetFlow Flow Sampling



Step 5 record {record-name | netflow-original | netflow {ipv4 | ipv6}record [peer]}

Example:



Step 6 end

Example:



Configuring and Enabling Flow SamplingTo configure and enable a flow sampler, perform the following required task.

SUMMARY STEPS

1. enable


3. sampler sampler-name


5. mode {deterministic | random} 1 out-of window-size

6. exit


8. {ip | ipv6} flow monitor monitor-name [[sampler] sampler-name] {input | output}

9. end

10. show sampler sampler-name

DETAILED STEPS


Step 1 enable

Example:

Device> enable



Configuring and Enabling Flow Sampling How to Configure Flexible NetFlow Flow Sampling




Example:



Step 3 sampler sampler-name

Example:

Device(config)# sampler SAMPLER-1

Creates a sampler and enters sampler configuration mode.

• This command also allows you to modify an existingsampler.


Example:

Device(config-sampler)# description Sample at 50%

(Optional) Creates a description for the flow sampler.

Step 5 mode {deterministic | random} 1 out-of window-size

Example:

Device(config-sampler)# mode random 1 out-of 2

Specifies the sampler mode and the flow sampler windowsize.

• The range for the window-size argument is from 2 to32,768.

Step 6 exit

Example:

Device(config-sampler)# exit

Exits sampler configuration mode and returns to globalconfiguration mode.


Example:

Device(config)# interface GigabitEthernet 0/0/0


Step 8 {ip | ipv6} flow monitor monitor-name [[sampler]sampler-name] {input | output}

Example:

Device(config-if)# ip flow monitor FLOW-MONITOR-1 sampler SAMPLER-1 input

Assigns the flow monitor and the flow sampler that youcreated to the interface to enable sampling.

Using Flexible NetFlow Flow SamplingHow to Configure Flexible NetFlow Flow Sampling



Step 9 end

Example:



Step 10 show sampler sampler-name

Example:

Device# show sampler SAMPLER-1

Displays the status and statistics of the flow sampler thatyou configured and enabled.

Configuration Examples for Using Flexible NetFlow FlowSampling

• Example: Configuring and Enabling a Deterministic Sampler for IPv4 Traffic, page 116• Example: Configuring and Enabling a Deterministic Sampler for IPv6 Traffic, page 117• Example: Adding a Sampler to a Flow Monitor When a Flow Monitor Is Already Enabled, page 117• Example: Removing a Sampler from a Flow Monitor, page 118

Example: Configuring and Enabling a Deterministic Sampler for IPv4 TrafficThe following example shows how to configure and enable deterministic sampling for IPv4 output traffic.


!flow monitor FLOW-MONITOR-1 record netflow ipv4 original-output exit!sampler SAMPLER-1 mode deterministic 1 out-of 2 exit!ip cef!interface GigabitEthernet 0/0/0 ip address 172.16.6.2 255.255.255.0 ip flow monitor FLOW-MONITOR-1 sampler SAMPLER-1 output!

The following example shows how to configure and enable deterministic sampling for IPv4 input traffic.


!flow monitor FLOW-MONITOR-1 record netflow ipv4 original-input exit!

Example: Configuring and Enabling a Deterministic Sampler for IPv4 Traffic Configuration Examples for Using Flexible NetFlow Flow Sampling


sampler SAMPLER-1 mode deterministic 1 out-of 2 exit!ip cef!interface GigabitEthernet 0/0/0 ip address 172.16.6.2 255.255.255.0 ip flow monitor FLOW-MONITOR-1 sampler SAMPLER-1 input!

Example: Configuring and Enabling a Deterministic Sampler for IPv6 TrafficThe following example shows how to configure and enable deterministic sampling for IPv6 output traffic.


!flow monitor FLOW-MONITOR-2 record netflow ipv6 original-output exit!sampler SAMPLER-1 mode deterministic 1 out-of 2 exit!ip cefipv6 cef!interface GigabitEthernet 0/0/0 ipv6 address 2001:DB8:2:ABCD::2/48 ipv6 flow monitor FLOW-MONITOR-2 sampler SAMPLER-1 output!

The following example shows how to configure and enable deterministic sampling for IPv6 input traffic.


!flow monitor FLOW-MONITOR-2 record netflow ipv6 original-input exit!sampler SAMPLER-1 mode deterministic 1 out-of 2 exit!ip cefipv6 cef!interface GigabitEthernet 0/0/0 ipv6 address 2001:DB8:2:ABCD::2/48 ipv6 flow monitor FLOW-MONITOR-1 sampler SAMPLER-1 input!

Example: Adding a Sampler to a Flow Monitor When a Flow Monitor IsAlready Enabled

The following example shows what happens when you try to add a sampler to a flow monitor that hasalready been enabled on an interface without a sampler:

Router(config)# interface GigabitEthernet 0/0/0 Router(config-if)# ip flow monitor FLOW-MONITOR-1 sampler SAMPLER-2 input% Flow Monitor: Flow Monitor 'FLOW-MONITOR-1' is already on in full mode and cannot be enabled with a sampler.

Example: Configuring and Enabling a Deterministic Sampler for IPv6 TrafficConfiguration Examples for Using Flexible NetFlow Flow Sampling


The following example shows how to remove the flow monitor from the interface so that it can be enabledwith the sampler:

Router(config)# interface GigabitEthernet 0/0/0Router(config-if)# no ip flow monitor FLOW-MONITOR-1 inputRouter(config-if)# ip flow monitor FLOW-MONITOR-1 sampler SAMPLER-2 input

Example: Removing a Sampler from a Flow MonitorThe following example shows what happens when you try to remove a sampler from a flow monitor on aninterface by entering the flow monitor command again without the sampler keyword and argument:

Router(config)# interface GigabitEthernet 0/0/0Router(config-if)# ip flow monitor FLOW-MONITOR-1 input% Flow Monitor: Flow Monitor 'FLOW-MONITOR-1' is already on in sampled mode and cannot be enabled in full mode.

The following example shows how to remove the flow monitor that was enabled with a sampler from theinterface so that it can be enabled without the sampler:

Router(config)# interface GigabitEthernet 0/0/0Router(config-if)# no ip flow monitor FLOW-MONITOR-1 sampler SAMPLER-2 inputRouter(config-if)# ip flow monitor FLOW-MONITOR-1 input




Flexible NetFlow conceptual and configurationinformation

Flexible NetFlow Configuration Guide


Standards/RFCs

Standard Title

No new or modified standards/RFCs are supportedby this feature.

--

Example: Removing a Sampler from a Flow Monitor Additional References



MIBs

MIB MIBs Link




Description Link



Feature Information for Flexible Netflow—Random SamplingThe following table provides release information about the feature or features described in this module.This table lists only the software release that introduced support for a given feature in a given softwarerelease train. Unless noted otherwise, subsequent releases of that software release train also support thatfeature.


Using Flexible NetFlow Flow SamplingFeature Information for Flexible Netflow—Random Sampling






Table 27 Feature Information for Flexible Netflow—Random Sampling


Flexible Netflow—RandomSampling

12.2(50)SY

12.4(20)T

Cisco IOS XE Release 3.1S

Cisco IOS XE Release 3.2SE

Flow samplers are created asseparate components in a router’sconfiguration. Flow samplers areused to reduce the load on thedevice that is running FlexibleNetFlow by limiting the numberof packets that are selected foranalysis. Samplers use eitherrandom or deterministic samplingtechniques (modes).

The following commands wereintroduced or modified: clearsampler, debug sampler ,mode , record , sampler , showsampler .



Using Flexible NetFlow Flow Sampling

