SNMP(Simple Network Management Protocol)

based

Network Management

SNMP(Simple Network Management Protocol)

based

Network Management

Network Management: What is it?

• Network management includes deployment,integration and coordination of the hardware, software, and human elements to monitor, test, poll, configure, analyze, evaluate and control the network and element resources to meet the real-time, operational performance, and Quality of service requirements at a reasonable cost.

Network Management: Why is it needed?

• Lowers costs by eliminating the need for many administrators at multiple locations performing the same function

• Makes network administration and monitoring easier and more convenient

• Coherent presentation of data

OSI Network Management Model

• ISO/OSI network management model defines a common frame of reference for network management, and provides an excellent framework for understanding the major functions that NMSs perform.

• The OSI network management model incorporates the following five layers:– Performance management– Fault management– Configuration management– Accounting management– Security management

Functional Areas of Network Management(According to OSI Network Management Model)

Functional Areas of Network Management(According to OSI Network Management Model)

Performance Management – how smoothly is the network running

Fault Management - reactive and proactive network fault management (deals with problems and emergencies in the network)

Configuration Management – keeping track of device settings and how they function

Accounting Management - cost management and charge back assessment

Security Management - SNMP (Version 1 and 2) doesn’t provide much here

In-Band Versus Out-of-Band Management

• When planning a distributed management solution, consider the path that the management data must take

• There are two path options for network management information—in-band and out-of-band

• In-band management traffic travels along the network data path

• Out-of-band management traffic alerts travel on a separate non-data path. An out-of-band management solution supports communications between management agents and the manager device, regardless of the status of the data network

In band/Out band Management

Out-of-Band Management In Band Management

N/w Management arch.

Network Management Architectures

1) Management Entity

• On the data collection end, two kinds of activities occur within a management utility or facility, called a management entity, whose job is to provide access to management data, controls, and behaviors:

1. Regular polling or sampling of management data occurs, whereby the management entity requests updates from managed devices to reflect recent status of the network being managed.

2. When alerts are received, appropriate responses must be generated

Network Management Architectures (contd.)

2) Managed Device

• A Managed device is a piece of network equipment that resides on a managed network.

• At each managed device, a special piece of software(process) called a management agent responds to polls for collected data, where the management agent itself has custody of a management database (MDB) of information that it collects and maintains over time

Network Management Architectures (contd.)

3) N/w Management Protocol

• The protocol runs between managing entity and the managed device.

• Allows the managing entity to query the status of the managed devices .

• Agents can use the network management protocol to inform the managing entity of exceptional events.

SNMP & The OSI ModelSNMP & The OSI Model

Management and Agent APIs7 Application LayerSNMP

6 Presentation Layer ASN.1 and BER5 Session Layer RPC and NetBIOS4 Transport Layer TCP and UDP3 Network Layer IP and IPX2 Data Link Layer1 Physical Layer

Ethernet, Token Ring, FDDI

VersionsVersions

•Two major versions SNMPv1, SNMPv2

•SNMPv1 is the recommended standard

•SNMPv2 has become split into:

•SNMPv2u - SNMPv2 with user-based security

•SNMPv2* - SNMPv2 with user-based security and additional features

•SNMPv2c - SNMPv2 without security

•SNMPv3 - Future

Client Pull & Server PushClient Pull & Server Push

• SNMP is a “client pull” model

• SNMP is a “server push” model

The management system (client) “pulls” data from the agent (server).

The agent (server) “pushes” out a trap message to a (client) management system

The Internet- Standard Management Framework

The Internet- Standard Management Framework

• SNMP is a tool (protocol) that allows for remote and local management of items on the network including servers, workstations, routers, switches and other managed devices.

• Comprised of agents and managers

•Agent - process running on each managed node collecting information about the device it is running on.

•Manager - process running on a management workstation that requests information about devices on the network.

SNMP network management consists of four parts:

The Internet- Standard Management Framework (contd.)

The Internet- Standard Management Framework (contd.)

•Structure of Management Information (SMI)•Structure of Management Information (SMI)•Rules specifying the format used to define objects managed on the network that the SNMP protocol accesses

•Management Information Base (MIB)•Management Information Base (MIB)•A map of the hierarchical order of all managed objects and how they are accessed

•SNMP Protocol•SNMP Protocol•Defines format of messages exchanged by management systems and agents.•Specifies the Get, GetNext, Set, and Trap operations

•Security and administration capabilities•The addition of these capabilities represents the major enhancement in SNMPv3 over SNMPv2

Registered Tree

MIB-2MIB-II Standard Internet MIB• Definition follows structure given in SMI • MIB-II (RFC 1213) is current standard

definition of the virtual file store for SNMP manageable objects

• Has 10 basic groups – system – interfaces – at – ip – icmp – tcp – udp – egp – transmission – snmp

• If agent implements any group then is has to implement all of the managed objects within that group

Ports & UDPPorts & UDP

•SNMP uses User Datagram Protocol (UDP) as the transport mechanism for SNMP messages

•UDP Port 161 - SNMP Messages

•UDP Port 162 - SNMP Trap Messages

•Like FTP, SNMP uses two well-known ports to operate:

Ethernet Frame IP

PacketUDP

Datagram

SNMP Message CRC

Four Basic OperationsFour Basic Operations

•Get

•GetNext

•Set

•Trap

Retrieves the value of a MIB variable stored on the agent machine

(integer, string, or address of another MIB variable)

Retrieves the next value of the next lexical MIB variable

Changes the value of a MIB variable

An unsolicited notification sent by an agent to a management application (typically a notification of something unexpected, like an error)

Basic operations contd..

Manager Agent

get_request

get_next_request

get_response port 161

port 161

port 161

port 161port 162

get_response

get_responseset_request

trap

TrapsTraps•Traps are unrequested event reports that are sent to a management system by an SNMP agent process

•When a trappable event occurs, a trap message is generated by the agent and is sent to a trap destination (a specific, configured network address)

•Many events can be configured to signal a trap, like a network cable fault, failing NIC or Hard Drive, a “General Protection Fault”, or a power supply failure

•Traps can also be throttled -- You can limit the number of traps sent per second from the agent

•Traps have a priority associated with them -- Critical, Major, Minor, Warning, Marginal, Informational, Normal, Unknown

Trap ReceiversTrap Receivers•Traps are received by a management application.

•Management applications can handle the trap in a few ways:•Poll the agent that sent the trap for more information about the event, and the status of the rest of the machine.

•Log the reception of the trap.

•Completely ignore the trap.

Languages of SNMPLanguages of SNMP

•Structure of Management Information (SMI)

•Abstract Syntax Notation One (ASN.1)

•Basic Encoding Rules (BER)

specifies the format used for defining managed objects that are accessed via the SNMP protocol

used to define the format of SNMP messages and managed objects (MIB modules) using an unambiguous data description forma

used to encode the SNMP messages into a format suitable for transmission across a network

SNMP MESSAGE ENCODING

• THE DESCRIPTION OF MIBS AND MESSAGE FORMATS IS BASED ON THE ASN.1 SYNTAX

• THE MAPPING FROM AN ABSTRACT SYNTAX UPON A

TRANSFER SYNTAX IS DEFINED BY THE BASIC ENCODING RULES (BER)

MANAGER

UDP

IP

LINK

AGENT

UDP

IP

LINK

MIB

BERBER

ABSTRACT SYNTAX

TRANSFER SYNTAX

Basic Message FormatBasic Message Format

Message Length

Message Version

Community String

PDU Header

PDU Body

Message Preamble

SNMP Protocol Data Unit

NAME 1 VALUE 1 NAME 2 VALUE 2 ••• ••• NAME n VALUE n

PDU TYPE* ERROR

VARIABLE BINDINGSSTATUSREQUEST

IDERRORINDEX

VERSION COMMUNITY SNMP PDU

variable bindings:

SNMP PDU:

SNMP message:SNMP MESSAGE

SNMP PDU

VARIABLE BINDINGS

SNMP AgentsSNMP Agents

Two basic designs of agents

•Extendible Agents•Extendible Agents

•Monolithic Agents•Monolithic Agents•not extendible

•optimized for specific hardware platform and OS

•not extendible

•optimized for specific hardware platform and OS

•Open, modular design allows for adaptations to new management data and operational requirements

Remote Monitoring (RMON)• The RMON MIB is used to monitor and administer remote segments

of a distributed network

• Within an RMON network monitoring data is defined by a set of statistics and functions and exchanged between various different monitors and console systems. Resultant data is used to monitor network utilization for network planning and performance-tuning, as well as assisting in network fault diagnosis.

• RMON places agents, called network probes, at various locations on the distributed network

• Probes are standalone devices that contain a NIC, a processor, memory, and software

Community NamesCommunity Names• A community string is a password that allows access to a network device.

It defines what "community of people" can access the SNMP information that is on the device.

• Community names are used to define where an SNMP message is destined for.

• Set up your agents to belong to certain communities.

• Set up your management applications to monitor and receive traps from certain community names.

• There are actually three community strings for SNMP-speaking devices:

• The SNMP Read-only community string

• The SNMP Read-Write community string

• The SNMP Trap community string

PROXY MANAGEMENT

• A NODE MAY NOT SUPPORT SNMP, BUT MAY BE MANAGEABLE BY SNMP THROUGH A PROXY AGENT RUNNING ON ANOTHER MACHINE

• TERM HAS TRADITIONALLY BEEN USED FOR DEVICES THAT :– TRANSLATE BETWEEN DIFFERENT TRANSPORT DOMAINS– TRANSLATE BETWEEN DIFFERENT SNMP VERSIONS– TRANSLATE BETWEEN SNMP AND OTHER MANAGEMENT PROTOCOLS– AGGREGATE LOW LEVEL MANAGEMENT INFO INTO HIGH LEVEL INFO ETC

• NOWADAYS THE TERM DENOTES A DEVICE THAT FORWARDS SNMP MESSAGES, BUT DOESN’T LOOK AT THE INDIVIDUAL OBJECTS

MANAGER PROXY AGENT

SNMP Consoles, Tools, Utilities, and Key Files

• There are many of these available, the lion’s share of the market belongs to three products:– HP Open View’s Network Node Manager

(NNM)– IBM’s Tivoli Net View– Computer Associates’ Unicenter TNG

• There are also many smaller utilities that are helpful when supporting a management system (Novell ManageWise, Sun MicroSystems Solstice, Microsoft SMS Server, Compaq Insight Manger, SnmpQL - ODBC Compliant,Empire Technologies,CincoNetworks NetXray,SNMP Collector Win9X/NT,Observer)

Architecture of NSM ProductsNSM products are made up of three layers:• WorldView Layer: repository for the graphical visualization of the

enterprise.– COR– Real World Interface– Worldview Application Interface

• Manager Layer: – Agent Technology: Contains the agent facilities that monitor and determine

the state of enterprise– Enterprise Management: A collection of integrated managers that control

and automate a variety of functions and responses within the enterprise

• Agent Technology Layer: Agents gather information from enterprise through remote access monitoring and control resource. Agents reside on or near managed objects and provide information to a management application.

Following steps outline what occurs architecturally when an agent detects a threshold breach on the device it is monitoring:

•Agent identifies a threshold has been crossed for a resource it is monitoring. It passes this information to the SNMP administrator by way of the Distributed Services Bus.

•The SNMP administrator takes the information from the Agent, encodes an SNMP Trap Protocol Data Unit and send it to the Manager.

•The SNMP Gateway receives the Trap PDU, decodes it, and sends it to the Manager by way of DSB.

•The Manager determines if the alert represents a change in status for the resource and, if so, passes the status update to the WorldView Gateway by way of DSB.

•The WorldView Gateway then updates the status of the managed object in the COR.

•Supports management of multiple distributed domains. Each server can import the map of one or more servers.

•Provides both local and remote access using the Remote Console Component.

•Polling agents perform discovery of locally attached devices.

About NSM Products

•Supports a multi-level hierarchy map. Each hierarchy can represent cities, buildings or sub networks.

•Automatically lays out each map network as a tree, ring, or snaked bus topology.

•Each map object uses a device specific or user selected icon, and the object color indicates the device status

•Automatically generates scheduled daily, weekly and monthly statistic reports. Report format include graph, bar chart, distribution,and summary and can be exported to a variety of destinations.

EXAMPLE NETWORK

Advantages of using SNMPAdvantages of using SNMP

• Standardized

• universally supported

• extendible

• portable

• allows distributed management access

• lightweight protocol

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