William Stallings Data and Computer Communications 7th Edition

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William StallingsData and Computer
Communications7th Edition

• Chapter 17
• Network Management

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Elements of Network Management

• ISO Management Functional Areas
• Fault Management
• Accounting Management
• Configuration Management
• Performance Management
• Security Management

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Fault Management

• Fault Management (FM)
• Detection of a problem
• Fault isolation
• Correction to normal operation
• FM involves the following steps
• Discover the problem.
• Isolate the problem
• Fix the problem (if possible)

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Accounting Management

• Individual cost centers or projects charged for
  use of network services
• Network manager needs to be able to track use of
  network
• User or group may be abusing access
• Users may be making inefficient use of network
• Need to plan for network growth

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Configuration and Name Management

• CM identifies, exercises control over, collects
  data from, and provides data to networked
  systems.
• Choose appropriate software and attributes and
  values (e.g., a transport layer retransmission
  timer) for device depending on function(s)
• Initializing network and gracefully shutting down
• Maintaining, adding, and updating relationships
  among components
• Status of components during network operation

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Performance Management

• Measuring the performance of network hardware,
  software, and media.
• Monitoring
• Tracks activities
• 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?
• Controlling
• Make adjustments to improve performance 
• Identify resources to be monitored
• Metrics and values for resources

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Security Management

• The process of controlling access to information
  on the networked system.
• The creation, deletion, and control of security
  services and mechanisms.
• The distribution of security-relevant
  information.
• The reporting of security-relevant events.

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Figure 17.1 Elements of a Network Management
System
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Key Components

• Manager (Management station)
• Agent
• Management information base (MIB)
• Network management protocol

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Management Components

• Management Station (Manager)
• Network management applications.
• Provide an interface which the human network
  manager can monitor and control the network.
• Agent
• Network devices should be equipped with agent
  software so that they can be managed from a
  management station.
• Responds to requests for information from
  managers.
• Responds to requests for actions from managers.
• May asynchronously provide managers with
  important but unsolicited information.

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Management Components (cont.)

• Network Management Protocol
• Communication protocol between managers and
  agents
• NM protocol provides a standard way to exchange
  management information between managers and
  agents.
• Management Information Base (MIB)
• A collection of Managed Objects.
• The resources to be managed are represented as
  objects, called Managed Objects (MOs).

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Management Information Base (MIB)
Managed Resources

• Each resource to be managed is represented by an
  object, called managed object (MO).
• The MIB is a structured collection of MOs.
• Essentially, each MO is a data variable.
• Each agent in an NE maintains an MIB.
• Monitor by reading the values of MOs in the MIB.
• Control by modifying the values of MOs in the
  MIB.

MIB
Agent
SNMP
UDP
IP
????
NE Network Element
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SNMP

• SNMP Simple Network Management Protocol
• De facto standards of network management for
  TCP/IP networks (Internet)
• Most TCP/IP network devices support SNMP.
• IETF SNMP Standards
• 1990 SNMPv1
• 1995 SNMPv2
• 1998 SNMPv3
• SNMPv1
• RFC 1157 SNMP protocol
• RFC 1155, 1212 SMI (Structure of Management
  Information)
• RFC 1213 MIB-II

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Figure 17.3 SNMPv1 Configuration
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Figure 17.4 The Role of SNMPv1
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SNMP Services
Manager
Agent(s)

• Get Request
• Retrieve the values of objects in the MIB of an
  agent.
• Get-Next Request
• Retrieve the values of the next objects in the
  MIB of an agent.
• Set Request
• Update the values of objects in the MIB of an
  agent.
• Trap Request
• Report extraordinary events to the manager.

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SNMP Message

• SNMP Message
• Version Identifier
• Community Name
• Protocol Data Unit
• The length of SNMP messages should not exceed
  484 octets.

Version
Community
SNMP PDU
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SNMP PDU
GetRequest, GetNextRequest, SetRequest
PDU type
request-id
0
0
variable-bindings
GetResponse
PDU type
request-id
variable-bindings
error-status
error-index
. . .
name
value
name
value
name
value
variable-bindings
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Trap-PDU
Trap-PDU 4 IMPLICIT SEQUENCE
enterprise OBJECT IDENTIFIER, agent-addr
NetworkAddress, generic-trap INTEGER
coldStart(0),
warmStart(1),
linkDown(2), linkUp(3),
authenticationFailure(4),
egpNeighborLoss(5),
enterpriseSpecific(6), spec
ific-trap INTEGER, time-stamp TimeTicks, vari
able-bindings VarBindList
Enterprise Type of Object generating
trap. Agent Address Address of object
generating trap. Generic Trap Generic trap
type. Specific Trap Enterprise specific
trap. Time Stamp Time elapsed between the last
initialization of the network entity and the
generation of the trap. Variable
Bindings Interesting information
PDU type
agent-addr
generic-trap
specific-trap
time-stamp
enterprise
variable-bindings
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MIB II

• MIB II contain 10 groups of managed objects
• System Group
• Provide general information about the managed
  system.
• Interfaces Group
• Contains generic information about the physical
  interfaces.
• Address-Translation Group
• Contains information about the mapping between
  network addresses and physical addresses for
  each physical interface.
• IP Group
• Contains information about the implementation and
  operation of IP at the managed system.
• ICMP Group
• Contains information about the implementation and
  operation of ICMP at the managed system.

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MIB-II (cont.)

• TCP Group
• Contains information about the implementation and
  operation of TCP at the managed system.
• UDP Group
• Contains information about the implementation and
  operation of UDP at the managed system.
• EGP Group
• Contains information about the implementation and
  operation of EGP at the managed system.
• Transmission Group
• Provides details about the underlying
  transmission media for each interface.
• SNMP Group
• Provides the statistics of SNMP operations at the
  managed system.