Chapter 19: Network Management. Business Data Communications, 5e

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Chapter 19:

Network Management

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Business Data Communications, 5e2

Fault Management

• A fault is an abnormal condition that

requires management attention (or action)

to repair

• Fault is usually indicated by failure to

operate correctly or by excessive errors

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Responding to Faults

• When faults occur, it is critical to quickly:

– Determine exactly where the fault is

– Isolate the rest of the network from the failure so that it can continue to function without interference

– Reconfigure or modify the network to minimize the effect of removing the failed component(s)

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User Requirements

for Fault Management

• Tolerant of occasional outages, but expect

speedy resolution

• Requires rapid and reliable fault detection

and diagnostic management functions

• Impact and duration of faults can be

minimized with redundancy

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Accounting Management

• Reasons for accounting management:

– Internal chargebacks on network use

– User(s) may be abusing access privileges and burdening the network at the expense of other users

– Users may be making inefficient use of the network

– Network manager can plan better for network growth if user activity is known in sufficient detail.

• Accounting reports should be generated under network manager control.

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Configuration Management

• Concerned with:

– initializing a network and gracefully shutting down part or all of the network

– maintaining, adding, and updating the relationships among components and the status of components themselves

during network operation

• Operations on certain components should be able to

be performed unattended

• Network manager needs the capability to change the

connectivity of network components

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Performance Management

• Issues of concern to the network manager

include:

– What is the level of capacity utilization? – Is there excessive traffic?

– Has throughput been reduced to unacceptable levels? – Are there bottlenecks?

– Is response time increasing?

• Network managers need performance statistics to

help them plan, manage, and maintain large

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Security Management

• Concerned with

– generating, distributing, and storing encryption keys – monitoring and controlling access to networks

– access to all or part of the network management information

– collection, storage, and examination of audit records and security logs

• Provides facilities for protection of network resources

and user information

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Network Management Systems

• Collection of tools for network monitoring and

control, integrated in these ways:

– A single user-friendly operator interface for performing most or all network management tasks

– A minimal amount of separate equipment

• Consists of incremental hardware and software

additions implemented among existing network

components

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Components of the NMS

• All nodes run the Network Management

Entity (NME) software

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Network Management Entity

• Collection of software contained in each network node,

devoted to the network management task

• Performs the following tasks:

– Collect statistics on communications and network-related activities.

– Store statistics locally

– Respond to commands from the network control center – Send messages to NCC when local conditions undergo a

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Simple Network Management

Protocol (SNMP)

• Originally developed for use as a network management tool for networks and internetworks operating TCP/IP. • A collection of specifications that include the protocol

itself, the definition of a database, and associated concepts.

• Network Management Model

– Management station – Agent

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SNMPv2

• Released in 1992, revised in 1996

• Addressed functional deficiencies in

SNMP

• Accommodates decentralized network

management

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Elements of SNMPv2

• Each "player" in the network management system

maintains local database of network management

information (MIB)

• Standard defines information structure and

allowable data types (SMI)

• At least one system must be responsible for

network management; others act as agents

• Information exchanged using simple

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Structure of Management

Information (SMI)

• Defines framework within which a MIB

can be defined and constructed

– data types that can be stored

– formal technique for defining objects and

tables of objects

– scheme for associating a unique identifier with

each actual object in a system

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SNMPv2 Protocol Operation

• Basic unit of exchange is the message

– Outer message wrapper

– Inner protocol data unit (PDU)

• Common fields in PDUs

– Request-id field is an integer assigned such that each outstanding request can be uniquely identified.