1 kyung hee university spring 2003 introduction to network management 6 may 2003 c.s. hong

Spring 200311Kyung Hee University

Introduction to Network Management Introduction to Network Management

6 May 2003

C.S. Hong


ContentsContents

SNMP Management Concepts

SNMP Management Information

XML-based Network Management

Network Monitoring


SNMP Network Management SNMP Network Management ConceptsConcepts


IntroductionIntroduction

ICMP (Internet Control Message Protocol) for transferring control

message from routers and other hosts to a host : the late 1970s

useful features : echo/echo-reply message pair, time stamp and time stamp reply message pair

a management tool : PING (Packet Internet Groper)

verifying the operation of a server observing variations in round-trip times and in datagram loss rates

Internet growing in the late 1980s

SGMP (Simple Monitoring Protocol) in Nov. 1987 ----> SNMP

HEMS (High-level Entity Management System) : generalization of Host Monitoring Protocol (HMP)

CMIP over TCP/IP (CMOT)


Introduction (cont’d)Introduction (cont’d)

In 1988, IAB approved further development of SNMP as short-term

solution and CMOT as the long-term solution

As a short-term solution

immediate implementation of SNMP based on SGMP– TCP/IP based network– IETF was responsible for the implementation– keep the protocol simple– focus on fault and configuration management

As a long-term solution

CMIS/CMIP for future requirements developed by the ISO non protocol specific (for use of all network devices)


Evolution of SNMPEvolution of SNMP

Development of a remote monitoring capability for SNMP

RMON (Remote Monitoring) MIB and addition to SNMP MIB for monitoring

Vendor-independent SNMP MIB and Vendor-specific SNMP MIB

SNMP v2 : dealing with security aspects

developed by members of the networking community in 1993, and revised in 1995

solve some of deficiencies with SNMP only for IP network relatively unsecured efficient table retrieval

SNMP v3 in 1998 : specifying use of cryptographic algorithms


SNMP-Related Standards by IETFSNMP-Related Standards by IETF

Foundation specifications

Structure and Identification for Information for TCP/IP-based networks (RFC 1155)

Management Information Base for Network Management of TCP/IP-based Internet: MIB-II (RFC 1213)

Simple Network Management Protocol (RFC 1157)


Network Management Architecture and Its Key Elements Network Management Architecture and Its Key Elements for TCP/IP Networkfor TCP/IP Network

Management station having :

a set of management application for data analysis and fault recovery

an interface for the network manager to monitor and control the network

a database of information extracted from the MIBs of all the managed entities in the network

the capability of translating the network manager’s requirements into the actual monitoring and control of remote elements in the network

Management agent

managed from a management station

providing the management station with important but unsolicited information


Network Management Architecture and Its Key Elements Network Management Architecture and Its Key Elements for TCP/IP Network (cont’d)for TCP/IP Network (cont’d)

MIB (Management Information Base)

representing resources as objects

data variables representing one aspect of the managed agent

management station performs the monitoring function by retrieving the value of MIB objects

Network management protocol

linking management station and agents

key capabilities of SNMP

get : retrieving the value of objects at the agent set : setting the value of objects at the agent trap : notifying the management station of significant events


Network Management Protocol ArchitectureNetwork Management Protocol Architecture SNMP implemented on the top of UDP ( or TCP), IP and relevant

network-dependent protocol (ex, Ethernet, FDDI, X.25, ATM,…)

Agent Process User process

SNMP FTP, etc

UDP TCP

IP

Network-dependentProtocol

Manager Process

SNMP

UDP

IP


Agent Process User processes

SNMP FTP, etc

UDP TCP

IP


Manager Process

SNMP

UDP

IP


Router

Host

Host

Management station

Networkmanager

Central MIB

Internetwork


Types of SNMP MessagesTypes of SNMP Messages

Managed resources

SNMP Manager

UDP

IP

Network-dependent protocols

Management application

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SNMP agent

UDP

IP

Network-dependent protocols

SNMP managed objects

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SNMP Messages

Applicationmanages objects

Network or Internet

SNMP agent

SNMP management station


ProxiesProxies

Manager Process

SNMP

UDP

IP


Agent Process

SNMP

UDP

IP


Management Process

Protocolarchitecture used by proxied device


Protocol architecture

used by proxied device


Mapping function Proxied device

Proxy agent

Management station


SNMP Management InformationSNMP Management Information


SNMP Management InformationSNMP Management Information

Database containing information about the elements to be managed : MIB

Each resource to be managed, to be represented by object

MIB : structured collection of such object having the form of tree

Structure of Management Information (SMI)

Specified in RFC 1155

Providing a standardized technique for defining the structure of a particular MIB

Providing a standardized technique for defining individual objects, including the syntax and the value of each object

Providing a standardized technique for encoding object values

SMI Data Type Additions To Structure of Management Information Version 2 (SMIv2) and Structure of Management Information Version 1 (SMIv1) : draft-perkins-smi-addition-00.txt

The new data types are Integer64, Unsigned64, Float, Double, and DiscUnion (discriminated union)


Defining objectsDefining objects

MIB (Management Information Base)

a precise definition of the information accessible through a network management protocol

each device must use the format for displaying information that is defined by the MIB

RFC 1052 define an extended MIB for use with SNMP and CMIS/CMIP is no longer realistic

RFC 1065: “Structure and Identification of Management Information for TCP/IP based Internets (SMI)”

describe the syntax and type of information available in the MIB for TCP/IP networks

RFC 1066 use the rules of the SMI present the first version of the MIB for TCP/IP known as MIB-I


Defining objects (cont’d)Defining objects (cont’d)

RFC 1155 (SMI)

RFC 1065 later was adopted by the IAB as a full standard four primitive data type

– INTEGER• 32bit value in two’s complement representation• -2147483648 ~ 2147483647

– OCTET STRING• zero or more octets• 0 ~ 255• represent a text string

– OBJECT IDENTIFIER• a sequence of integers• traverse a hierarchical MIB tree

– NULL


Defining objects (cont’d)Defining objects (cont’d)

RFC 1156

allow for expansion of the MIB for vendor specific enhancement

RFC 1158

propose a second MIB (MIB-II) extend the information base defined in MIB-I Note: most network devices have software agent that support MIB-II and their own

private extensions

Each MIB would focus on a specific technology

RFC 1743: IEEE 802.5 Token Ring Interface type MIB RFC 1757: Remote Network Monitoring MIB (RMON) RFC 1513: FDDI Interface type MIB RFC 1493: Bridge MIB


MIB StructureMIB Structure

Leaf objects of the tree to be actual managed objects to represent

some resource, activity, or related information

Object identifier : a unique identifier for particular object type

Serving as the name of an object

internet OBJECT IDENTIFIER :: = { iso (1) org(3) dod (6) 1}

therefore, internet node’s object ID : 1.3.6.1

four nodes under the internet node

directory mgmt ----> mib-1, mib-2 experimental private


MIB Structure (cont’d)MIB Structure (cont’d)

Object Identifier

ISO ASN.1 (Abstract Syntax Notation One) Syntax

a subset of ASN.1 defines the syntax for the MIB use the tree architecture to organize all available information

– labeled node– object identifier (OID) and text description

Object ID consisting of sequence of integers

for example : object ID for tcpConnTable : 1.3.6.1.2.1.6.13

iso org dod internet mgmt mib-2 tcp tcpConnTable

1 3 6 1 2 1 6 13


MIB TreeMIB Tree

Traversal of the MIB tree

root node

itu-t (0), administered by the ITU-T iso (1), administered by the ISO joint-iso-itu-t (2), jointly administered by ISO and ITU-T

– internet: OID= 1.3.6.1 or {iso org(3) dod(6), 1}

ITU-T(0) ISO(1) joint-ISO-ITU-T (2)

…. org(3) …..

….. dod(6) …..

….. internet (1) …..

directory(1) …… mgmt(2) …. Experimental(3) private(4)

mib(1) enterprises(1)


MIB Tree (cont’d)MIB Tree (cont’d) directory (1)

– reserved for future use mgmt(2)

– MIB-I originally assigned OID 1.3.6.1.2.1 or {mib 1}– MIB-I has been superseded by MIB-II– system(1): network device operating system– interfaces(2): network interface specific– address translation(3): address mappings– ip(4): Internet protocol specific– icmp(5): ICMP specific– tcp(6): transmission protocol specific– udp(7): user datagram protocol specific– egp(8): exterior gateway protocol specific– cmot(9): CMIP on TCP specific– transmission(10): transmission media specific– snmp(11): SNMP specific


MIB Tree (cont’d)MIB Tree (cont’d)

experimental (3)– experimental protocols and MIB development intended to enter the standards tr

ack private(4)

– used to specify objects defined unilaterally– enterprises(1) or {private 1}

• an organization that has registered its own specific extensions to the MIB• vendor-specific MIBs are found• OID (1.3.6.1.4.1)

OIDs represent each manageable object with a unique sequence of numbers and names

SNMP uses the number as an abbreviated form of the name – to make requests for data values– to identify each response that carries the values


MIB : An ExampleMIB : An Example

tcpMaxConn OBJECT-TYPE

SYNTAX INTEGER

ACCESS read-only

STATUS mandatory

DESCRIPTION

“The limit on the total number of TCP connections the entity can support. In entities where the maximum number of connections is dynamic, this object should contain the value -1.”

::= { tcp 4 }

* OID :1.3.6.1.2.1.6.4


Macro object definitionMacro object definition

Object : having a type (syntactic description) and value

To extend ASN.1 to define new types and their values

Macro definition : specifying the syntax of a set of related types

Macro instance : an instance generated from a specific macro defi

nition

Macro instance value : representing a specific entity with a specifi

c value

Macro used for the SNMP MIBs : RFC1155 for MIB-I, RFC 1212 (con

cise MIB definitions) for MIB-II


Private MIBsPrivate MIBs

MIB has been designed to accommodate growth and to provide fle

xibility for adding new objects.

Private extensions can be added to the private subtree

The management station must be loaded with the private MIB stru

cture

The potential for difficulty arises when the two are from different

vendors

Most vendors supply both a text version and a formal description of their MIB extensions

But, vendors can use different formats


SNMP OperationSNMP OperationThe five SNMPv1message types (RFC1157)

Get-Request: retrieve information from device Get-Response: agent responds to the Get-Request Get-Next-Request: ask for the next specific object Set-Request: for remote configuration parameter Trap: an unsolicited message

Host

MS-DOS Router

Terminal server Device

Data Network

station

Managing host

agentagentagent

agentagent


SNMP Operation (cont’d)SNMP Operation (cont’d)Format of SNMP

SNMP

ISO presentation

ISO session

UDP

IP

ISO data link

Physical

Layer 7

Layer 6

Layer 5

Layer 4

Layer 3

Layer 2

Layer 1

Version Community PDUtype

Request ID

0 0 Name X Value X ……..


Request ID

Errorstatus

Errorindex

Name X Value X ……...

Get-Request, Get-Next-Request, Set-Request

Get-Response


Enterprise Agentaddr

Generic trap

Specific trap

Time Name X Value X

Trap


SNMP Operation (cont’d)SNMP Operation (cont’d)

SNMP trap

an unsolicited message an agent sends to a station inform the server about the occurrence of specific event seven types of SNMP traps (MIB-II)

– coldstart of a system: reinitializing itself such that its configuration or protocol has changed

– warmstart of a system: reinitializing itself such that its configuration or protocol has not changed

– link down: a specific link has failed

stationDevice

agent

Data Network

Link failure

Trap: interface #2, link down

Managing host


SNMP Operation (cont’d)SNMP Operation (cont’d)– link up: a specific link has come up– failure of authentication: a request does not provide proper authentication– EGP (Exterior Gateway Protocol) neighbor loss

• EGP is a reachability protocol used between data networks

– enterprise specific• a vendor to provide additional functionality that complements the generic tra

ps

security

community string– station sends a particular password with each message– the password is referred to as the SNMP community string


SNMP V2 & V3SNMP V2 & V3

SNMPv2

The key enhancements to SNMP that are provided in SNMPv2

Structure of Management Information (SMI) Manager-to-manager capability Protocol operations

Most noticeable change in protocol operations

GetBulkRequest PDU : enabling the manager to retrieve large blocks of data efficiently. It is well suited to retrieving multiple rows in a table

InformRequest PDU : enabling one manager to send trap of information to another

Additional types

Integer32 Counter32 Gauge32 Unsigned32 Counter64


SNMP V2 & V3 (cont’d)SNMP V2 & V3 (cont’d)

SNMPv3

Adding cryptographic algorithms


RMON 1 and 2RMON 1 and 2 Defining a remote monitoring MIB that supplements MIB-II

Providing the network manager with vital information about the internetwork

Providing significant expansion in SNMP functionality

RMON-Related RFCs

RFC 1513 : Token Ring Extensions to the Remote Network Monitoring MIB

RFC 1757 : Remote Network Monitoring Management Information Base

RFC 2021 : Remote Network Monitoring Management Information Base II

RFC 2074 : Remote Network Monitoring MIB Protocol Identifiers

RFC 2613 Remote Network Monitoring MIB Extensions for Switched Networks Version 1.0. (proposed standard) June 1999

RFC 2819 : Remote Network Monitoring Management Information Base, May 2000. (obsolete RFC1757)

RFC 2895 : Remote Network Monitoring MIB Protocol Identifier Reference, August 2000. (obsolete RFC 2074)

RFC 2896 : Remote Network Monitoring MIB Protocol Identifier Macros, August 2000. (informational)


RMON GoalsRMON Goals

Defining standard network-monitoring functions and interfaces for communicating between SNMP-based management consoles and remote monitors

Designing Goals for RMON described in RFC 1757

off-line operation : to limit or halt the routine polling of a monitor by network manager

Proactive monitoring : using running diagnostics and logging network performance

Problem detection and reporting

Value-added-data : performing analyses specific to the data collected on its subnetwork

ex) analyzing subnetwork traffic to determine which hosts generate the most traffic or errors on the subnetwork

Multiple managers

for improving reliability for performing different functions (ex, engineering and operations) for providing management capability to different units within an organization


RMON Goals (cont’d)RMON Goals (cont’d)

A system that implements the RMON MIB is referred to as an

RMON probe.

no different from any other SNMP agent


RMON Goals (cont’d)RMON Goals (cont’d)


OID Tree for RMONOID Tree for RMON

ITU-T(0) iso(1) joint-iso-ITU-T (2)

…. org(3) …..

….. dod(6) …..

….. internet (1) …..

directory(1) …… mgmt(2) …. Experimental(3) private(4)

Mib-2(1) enterprises(1)

system(1) interfaces(2) at(3) ip(4) icmp(5) tcp(6) udp(7) egp(8) cmot(9) transmission(10) snmp(11) Rmon(16)…... ……...


Network-Layer Visibility of RMONNetwork-Layer Visibility of RMON

RMON probe with RMON1 can monitor all of the traffic on the

LANs, or can capture all of the MAC-level frames and read the

MAC-level source and destination addresses in those frames.

But, no way of determining the ultimate source of incoming traffic arriving via the router or the ultimate destination of outgoing traffic leaving via the router.

With RMON2, the RMON probe has the capability of seeing above

the MAC layer by reading the header of the enclosed network-layer

protocol, which is typically IP.

analyzing traffic passing through the router to determine the ultimate source and destination.


The RMON MIBThe RMON MIB

rmon (mib-2, 16)

statistics (1)

history (2)

alarm (3)

host (4)

hostTopN (5)

matrix (6)

filter (7)

capture (8)

event (9)

tokenRing (10)

protocolDir (11)

ProtocolDist (12)

addressMap(13)

nlHost (14)

nlMatrix (15)

alHost (16)

alMatrix (17)

usrHistory (18)

probeConfig (19)

rmonConformance (20)

RMON1RMON2


XML-based Network ManagementXML-based Network Management


IntroductionIntroduction eXtensible Markup Language (XML)

A simplified subset of the Standard Generalized Markup Language (SGML)

XML is an emerging technology for Web-based applications and has been

in the spotlight.

XML has many advantages

Simplicity, openness, extensible, inexpensive

Most people believe that XML will succeed much more than HTML, HTTP,

Web, Java

Advantages in XML-based network management

Easy to learn: not management domain specific technology

Large supporting tools and technology: Low development cost

High compatibility with legacy management technology: Integrated manageme

nt.


XML : What is XML ?XML : What is XML ? What does “XML” stands for?

eXtensible: not a fixed format, customizable.

Markup: used to define things.

Language: used to communicate or describe and encapsulate its information and pass it.

XML was designed to describe data.

Document Type Definition (DTD) or XML Schema is used.

XML is self-descriptive.

XML is free and extensible.

XML allows the author to define his own tags.

XML is a compliment to HTML.

XML will be used for describing data and HTML for displaying same data.

XML is a future Web technology.

Quick standard process, large support by vendor.

Common tool for all data manipulation and data transmission.


XML : An ExampleXML : An Example

A Telecom example

<?xml version=“1.0” ?>

<?xml:stylesheet type="text/xsl" href="schema.xsl"?>

<n-entityCreation id="1">

<ems id="TaskCenter">

<mgdEltR1 id="NE1" adminState="unlocked“ opState="enabled">

<equipHolder id="1" equipHolderType="Bay">

<equipHolder id="3" holderType="Shelf">

<equipHolder id="4" holderType="Slot">

</equipHolder>

</equipHolder>

</equipHolder>

</mgdEltR1>

</ems>

</n-entityCreation>

PI targetPI value

PI : Processing Instruction


XML : Technology MapXML : Technology Map

XML

ProgramScripts

DatabaseEditor(file)

Input

Generate

DTD, XML Schema

DefineValidate

DOM

DumpParse

Program

Process

WAP, XHTML

Standard

XSLXSLT

XPath

Input WebBrower

Input

SOAP RemoteSystem

Exchange

Input


XML : DTD and XML SchemaXML : DTD and XML Schema

DTD (Document Type Definition)

Defines the document structure with a list of legal elements

Can be declared inline in XML document, or as an external reference.

XML Schema

A successor to DTD.

Support for Data Types

Provides inclusion and derivation mechanisms

Uses XML as encoding syntax

Why use DTD/XML Schema?

Each XML file can carry a description of its own format.

To verify the data you received or your own data.

Independent groups of people can agree to use a common DTD for interchanging data.


XML : DTD ExampleXML : DTD Example

<!DOCTYPE lecturer [ <!ELEMENT lecturer (name, (email | hp)?)> <!ELEMENT name (#PCDATA)> <!ELEMENT email (#PCDATA)> <!ATTLIST lecturer class CDATA #REQUIRED> ]>

seminar.dtd

<?xml version=“1.0”?><!DOCTYPE lecturer SYSTEM “seminar.dtd”> <lecturer class=“XML”> <name>cshong</name> <email> … </email> </lecturer>

<?xml version=“1.0”?><!DOCTYPE lecturer SYSTEM “seminar.dtd”> <lecturer class=“XML”> <name>cshong</name> <email> … </email> </lecturer>

Description Verification


XML : DOMXML : DOM

Document Object Model (DOM)

Definition

A programming interface to access and manipulate XML documents

Objectives

To provide a standard programming interface to a wide variety of applications

can create an XML document, navigate its structure, and add, modify, or delete its elements

can be used with any programming language on any operating system


XML : DOM exampleXML : DOM example

DOMTree

lecturer

class

document

name

juht

<?xml version=“1.0”?><lecturer class=“XML”> <name> cshong </name> </lecturer>

Parsing Serialization

DOM APIApplicationswritten in

any language


Applicability of XMLApplicability of XML

Basic management tasks

Management Information Modeling.

Description framework for managed resource to managed object.

Management Information Realization.

Guarantees of consistency between managed resource and managed object.

Management Information Distribution.

Exchange of management information between management applications.

Management Information Analysis.

Process of management information production from collected information.

Management Information Presentation.

User interface for display management information or taking management command from operators.


Basic Management TasksBasic Management Tasks

Modeling

Realization

Distribution

Presentation

Manager

Agent

Analysis


Management Information ModelingManagement Information Modeling

Standard Information model

XML Schema for management information modeling

Advantages

Easy to learn, not domain specific technology. Use of powerful and convenient graphical XML editor. Modeling result is concise and easy to read. Secondary benefits – validation, sample data generation.

Disadvantage

No standard models, but easy to translate from standard information models.

SNMP TMN DMTF XML

Tool SMI GDMO CIM XML Schema

Models MIB-II G.721 CIM v.6 No standard yet

Approach Object-based Object-oriented Object-oriented Object-oriented


Management Information RealizationManagement Information Realization

Standard management frameworks leave it completely unspecified - viewed as a “local matter”.

Model specification serves as a starting point for the coding of the agents.

For Web interface and CLI, the model specification was not provided.

For SNMP, MIB compilers have been used to generate MIB stubs.

The stubs are supplemented with the code for actual access to resources.

There is no common interface or data format between managed resource and management agents such as CLI, SNMP, Web.

Large development cost and footprint.

Consistency problem by multiple access to single managed resource.

XML for management information realization

XML can be used for middleware between agents and managed resources.

Low footprint solution.

Various methods can be used for XML generation.


Management information distributionManagement information distribution Communication between management applications

Agent ↔ Manger, Manager ↔ Manager Standard management communications

North bound interface is usually based on CORBA.

XML and CORBA are interoperable technologies.

XML does not say anything about communication protocol, Implicitly HTTP is used.

Reliable, efficient by compression, highly secure, high connectivity.

Flexible by use of SOAP.

SNMP TMN DMTF XML

Protocol SNMP/UDP CMIP Operations/HTTP SOAP or HTTP

Operation Get, Set,

GetNext, Resp

onse

M-Get, M-Set , M-

Create, M-Delete, M-

Action

GetInstance, SetInstance,

GetClass, etc. (23 Operatio

ns)

Unspecified

Notification Trap M-Event_Report Unspecified Unspecified

Encoding ASN.1 ASN.1 XML XML


Management Information AnalysisManagement Information Analysis

This has not been standardized and based on data processing such as

sorting, filtering, logging and correlating.

Management platforms provide basic management functionality and

development environment.

Their price is usually very expensive.

Customization requires large amount of time and effort.

In most cases, they do not depend on standard technology.

Recently, CORBA has been used widely as an implementation platform for

management systems.

XML for management information analysis.

XML is a standard data processing tool.

Many supporting tools (such as database) are available.

Lots of developers having XML knowledge.


Management Information PresentationManagement Information Presentation

This allows user interactive access to the management system.

+: Include telnet connection.

#: MS-Windows or X-Windows

*: Without use of XML technologies.

XML for management information presentation

Separation with display and data in Web environment.

Platform independent standard display technology.

Device dependant display support.

Ubiquitous management user interface.

User-friendly graphic interface.

Text+ Windows# Web* XML

Ubiquity Best Bad Good Good

Interactivity Bad Best Good Good

Development cost Low High Middle Low

User-friendliness Worst Good Best Best


State of the Art for XML-based NMState of the Art for XML-based NM

Research work

Complimentary approaches to SNMP

eXtensible Network and System Management Instrumentation. SNMP to XML translator XML/SNMP Gateway

Improvement approaches to Web-based network management

Direct Web Interface for Device Configuration XML-based Device Configuration

New Management Architectures

XML-based Service Configuration Web-based Integrated Management Architecture XML-based Network Management Architecture

Standard Activities

Web Based Enterprise Management (WBEM)


SNMP to XML TranslatorSNMP to XML Translator

Applications of SNMP to XML translator

1. Encoding SNMP MIB data

2. Information analysis or presentation for SNMP MIB data

3. Specification translation for SNMP to XML gateway

XML/HTTP SNMP Agent

Web Server

SNMP

SNMPGW

XML


XML/SNMP GatewayXML/SNMP Gateway

What is XML/SNMP Gateway?

Relays management information and operations between SNMP agent and XML-based manager system.

While preserving the legacy SNMP agent, one can develop XML-based manager by using XML technology.

Two basic requirements for the gateway

Specification translation: SNMP MIB XML– For understanding the management information exported by SNMP

agent. Interaction translation: SNMP Operations XML Operations

– For supporting interaction between two management applications


Direct Web Interface to Managed DevicesDirect Web Interface to Managed Devices Traditional Approach

Result of embedding small Web server into network device.

Ubiquitous, simple but powerful, user-friendly device management user interface.

XML Approach (EmWeb XML parser)

XML generation by program is enough small solution to be embedded.

Separate display format and data generation.

XML parser can save development cost by generating backend stub code based on XML schema.

Embedded Web Server

HTML or Java / HTTP

Embedded Web Server

XML & XSL / HTTP


Network Monitoring Network Monitoring


Generic MetricsGeneric Metrics

Availability

Connectivity

Functionality

Loss

One way loss

Round trip loss

Delay

One way delay

Round trip delay

Delay variance

Utilization

Bandwidth

Throughput


Network Monitoring Network Monitoring Active Approach

Performed by sending test traffic into network

1) Generate Test packet periodically or on-demand

2) Measure performance of test packet or response

3) Take the statistics

Impose extra traffic on network and distort its behavior in the process

Used to monitor network performance

e.g., Availability, Delay, Loss


Network Monitoring (cont’d)Network Monitoring (cont’d) Passive Approach

Carried out by observing normal network traffic

1) Collect network flow from device or generate it after capturing

2) Perform analysis for the purpose

Using high-performance computing device (harder as traffic rates increase)

Used to perform traffic characterization analysis

Spatial, temporal and composition


Questions ?Questions ?

1 kyung hee university spring 2003 introduction to network management 6 may 2003 c.s. hong

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