Network Management

1
Network Management

• Chapter 8

2
Network Management Requirements

• Fault Management
• Accounting Management
• Configuration and Name Management
• Performance Management
• Security Management

3
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
• Users expect quick and reliable resolution

4
Accounting Management

• Reasons for accounting management
• Users may be abusing access privileges and
  burdening the network at the expense of other
  users
• Users may be making inefficient use of the
  network
• The network manager is in a better position to
  plan for network growth if user activity is known
  in sufficient detail.

5
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

6
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
  networks

7
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

8
Network Management Systems

• Collection of tools for network monitoring and
  control, integrated in these ways
• A single user-friendly interface for performing
  most or all network management tasks
• A minimal amount of separate equipment
• consists of additional hardware and software
  implemented among existing network components

9
Network Management System Architecture
10
Four components of the NMS

• Managed nodes
• Management station
• Management Information
• Management Protocol

11
Managed nodes

• Devices which are capable to exchange status
  information with the outside world (e.g. hosts,
  routers etc..)
• Must be capable of running an SNMP management
  process (SNMP agent)
• Maintains a local database which describes the
  nodes state and history

12
Management station

• A computer running special management software
  (SNMP management software)
• Can communicate with the agents over the network
  (issue commands and get the response)
• It is generally put the intelligence in the
  management stations so that the design of the
  agent can be simple which can then minimize the
  impact on the device they (agents) are running on.

13
Management Information

• Each device (agent) maintains one or more
  variables (so called objects) which describe the
  device's state.
• The collection of objects is stored in a data
  structure so called Management Information Base
  (MIB). The MIB holds relevant management
  information.

14
Simple Network Management Protocol (SNMP)

• Designed in the mid-1980's as an answer to the
  communication problems between different types of
  networks.
• Consists of a simply composed set of network
  communication specifications that cover all the
  basics of network management in a method that
  poses little stress on an existing network.
• Each SNMP device (router, gateway, server) has an
  agent that collects information about itself and
  the message it processes, and stores that
  information in a database called the management
  information base (MIB) .

15
Role of SNMP
Transmission of a message Receipt of a
message Variable bindings
16
OSI Object Identifier Tree
17
Object Naming In MIB

• Question how to name every possible standard
  object (protocol, data, more..) in every possible
  network standard??
• Answer ISO Object Identifier tree
• hierarchical naming of all objects
• each branchpoint has name, number

1.3.6.1.2.1.7.1
udpInDatagrams UDP MIB2 management
ISO ISO-ident. Org. US DoD Internet
18
SNMP Protocol
Two ways to convey MIB info, commands
trap msg
response
Managed device
Managed device
request/response mode
trap mode
19
SNMP Protocol

• Network information is exchanged through the
  messages called protocol data units (PDU's). The
  PDU can be looked at as an object that contains
  variables that have both titles and values.

20
SNMP Protocol

• Five types of PDU's employed to monitor a
  network
• two deal with reading terminal data,
• two deal with setting terminal data,
• and one, the trap, is used for monitoring network
  events such as terminal start-ups or shut-downs.
• To see if a terminal is attached to the network,
  a user uses SNMP to send out a read PDU to that
  terminal.
• If the terminal was attached to the network, the
  user would receive back the PDU, it's value being
  "yes, the terminal is attached".
• If the terminal was shut off, the user would
  receive a packet informing them of the shutdown.

21
SNMP PDUs
Get-Request
Get-Response
Get-Next-Request
Manager
Agent
Set-Request
Trap
22
SNMP PDUs

• Get-Request
• - Access the agent and obtain values from a list
• - Contains identifiers to distinguish it from
  multiple requests
• - Provide information about the status of the
  network element
• Get-Next-Request
• - Similar to the Get-Request , except that it
  retrieves the value of the next logical
  identifier in the MIB tree

23
SNMP PDUs

• Get-Response
• Response to the Get-Request, Get-Next-Request and
  the Set-Request data units
• Contains identifiers to provide information about
  the status of the response ( error code and error
  status, etc)
• Set-Request
• An action to be performed on an element
• Used to change the values of a variable element

24
SNMP PDUs

• Trap
• Allow the network management software to report
  on an event at a network element or change the
  status of a network element

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