Fundamentals of Network Management

Network Management Standards OSI

Common Management Information Protocol (CMIP) International standard (ISO / OSI) Management of data comm. Network LAN and WAN Deals with all 7 layers Most complete Object oriented representation Well structured and layered Consumes large resources in implementation

Internet Simple Network Management Protocol (SNMP) Industry standard (IETF) Originally intended for management of Internet components, currently

adopted for WAN and telecom systems. Easy to implement

Most widely implemented NM standard. Lacks advanced functionality (compared to CMIP)

Network Management Standards (…) Telecommunication Management Network (TMN)

International standard of the ITU-T Management of telecom networks Based on the OSI network management framework Addresses both network, administrative, and business aspects of

management. IEEE

Addresses LAN and MAN management. Deals with the first 2 layers.

Web-based Management Web-based Enterprise Management (WBEM) Java Management Application Program Interface (JMAPI)

Management Architecture

This architecture is used for both OSI and SNMP-based management

Consists of a number of models

OSI Models

Organization Network management components Functions of components Relationships

Information Structure of Management Information (SMI)

Syntax and semantics Management Information Base (MIB)

Organization of management information Communication

Transfer syntax with bi-directional messages Transfer structure (PDU)

Functions Application functions

Configure components Monitor components Measure performance Secure information Usage accounting

SNMP Architecture and Models

Organization Same as OSI model

Information Same as OSI, but scalar

Communication Messages less complex than OSI and unidirectional Transfer structure (PDU)

Functions Application functions

Operations Administration Security

Organizational Model

Manager Sends requests to agents Monitors alarms Houses applications Provides user interface

Agent Gathers information from objects Configures parameters of objects Responds to managers’ requests Generates alarms and sends them to mangers

Managed object Network element that is managed Houses management agent All objects are not managed / manageable

Organization Model

Managed object Manage objects can be

Network elements (hardware, system) hubs, bridges, routers,

transmission facilities Software (non-physical)

programs, algorithms Administrative information

contact person, name of group of objects (IP group)

Houses SNMP management agent Objects are classified into

managed/unmanaged Managed object has a running

management agent

Manager

Managed objects

Unmanaged objects

Two-Tier Network Management Organization Model

Agent process

MDB

MDB Management Database

Organization Model

Management Station (Manager) Interface for network managers to

monitor and control the network

Contains management applications

(data analysis, fault recovery, etc.)

Translation capabilities from

manager’s requirements into actual

monitoring and control of remote

elements

Contains DB of information extracted

from MIBs of all the managed entities

in the Network

Manager

Managed objects

Unmanaged objects

Two-Tier Network Management Organization Model

Agent process

MDB

MDB Management Database

Organization Model

Management Agent Gathers information from objects

Configures parameters of objects

(e.g., enable/disable a router port,

shut down a port on a hub, etc.)

Responds to requests for

information and actions from

managers

Generates alarms and sends

them to managers

Manager

Managed objects

Unmanaged objects

Two-Tier Network Management Organization Model

Agent process

MDB

MDB Management Database

Organization Model

Middle layer plays the dual role Agent to the top-level manager Manager to the managed objects

collects, processes and stores data locally

Performs statistical operation on the data and passes it to top level manager

The intermediate system could be at a local site and passes info. to a remote site.

Example of middle level: Remote monitoring agent (RMON)

Agent / Manager

Managed objects

Agent process

Manager

Three-Tier Network Management Organization Model

MDB

MDB

MDB Management Database

Organization Model

Different network domains, each managed locally Agent NMS manages the domain MoM presents integrated view of domains Domain may be geographical, administrative, vendor-specific

products, etc.

MoM

Agent

Agent NMSManager

Managed objectsManaged objects

MDB

MDB MDB

MoM Manager of Managers

Agent

Agent NMSManager

NMS Network Management System

Peer NMSs

Dual Role of Management Process

Communication Model

Resources are represented as objects (or data variables) Collection of objects is a MIB (more later) A manager performs monitoring by retrieving the value of MIB

objects A manager causes an action to take place or changes the

configuration settings by modifying values of specific variables

MIB

MANAGERMANAGER AGENTAGENT

SNMP

Communication Model

Management stations and agents are linked by a network management protocol

SNMP is used for the management of TCP/IP networkso Get: manager or management station can retrieve the value of

objects at the agento Set: set the values of objects at the agento Trap: agent notifies manager on significant events

MIB

MANAGERMANAGER AGENTAGENT

SNMP

Protocol Architecture

InternetworkInternetwork

Router

IP

Network-dependent protocols

UDP

SNMP

Agent processAgent process

SNMP

UDPUDP

SNMP

Agent processAgent process

SNMP

UDP UDP

SNMP

Agent processUser process

FTP, etc.

TCP

Host

IP

Network-dependent protocols

Host

UDP

SNMP

Agent processAgent process

SNMP

UDP UDP

SNMP

Agent processUser process

FTP, etc.

TCP

IP

Network-dependent protocols

IP

UDP

SNMP

Manager process

Network-dependent protocols

Management station

Network manager

Central MIB

(e.g., Ethernet, X.25, ATM)

Interprets SNMP messages and controls the agent’s MIB

-SNMP uses UDP port 161- connection-less

Communication Model

Management data is communicated between agent and manager as well as between managers

Three aspects: Transport medium of message exchange (transport protocol) Message format (application protocol) Actual message (commands and responses)

Manager Agent

Operations /Requests

Responses

Notifications /Traps

ApplicationsNetwork Elements Managed Objects

Management Message Communication Model

Communication ModelG

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Se

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t

Ge

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spo

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Tra

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Layer 1 & 2

IP

SNMP Manager

UDP

Layer 1 & 2

IP

SNMP Agent

UDP

NetworkG

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Ge

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Managementapplication

SNMP managedobjects

Application

manages object

SNMP Messages

Central MIB

Trap-Directed Polling

SNMP encourages the manager to use trap-directed polling A manager may be

responsible for a large number agents, each maintains a large number of managed objects

It is impractical to regularly poll all agents for all their readable objects (management overhead on the network may be very excessive!)

agent data

agent data

agent data

agent data

managed device

managed device

managed device

managed device

managingentity data

networkmanagement

protocol

managing entity

Trap-Directed Polling

Initially a manager may poll all the agents for some key information e.g., interface characteristics

(# pckts in/out, etc..)

Then, each agent is responsible for notifying (through trap messages) the manager of any unusual event e.g., high pckt drop rate at

some interface

agent data

agent data

agent data

agent data

managed device

managed device

managed device

managed device

managingentity data

networkmanagement

protocol

managing entity

Information Model

The representation of objects and information relevant to their management

This information is usually communicated between agents and management processes

SMI (Structure of Management Information) defines the syntax and semantics of management information stored in MIB (Management Information Base)

ExamplesysDescr: { system 1 }Syntax: OCTET STRINGDefinition: "A textual description of the entity. "Access: read-onlyStatus: mandatory

MIB Contains information about objects Organized by grouping of related objects Defines relationship between objects Agent MIB vs. Manager MIB

MIB Agent: local information MIB Manager: info. on all network

components

Information Model

MDB physical database; e.g.. Oracle Contains measured or administratively

configured values of NEs MIB virtual database; schema compiled into

management software Info necessary for processes to exchange info.

(e.g., #ports/hub) A NMS can automatically discover (periodic

broadcast of PING messages) a managed object, such as a hub, when added to the network Once detected, its information (e.g., address,

number of ports, etc.) is added to MDB MIB does not need to be updated if another hub

from same vendor already exist

Manager

Managed objects

MDB MIB

Management Information Tree

Both Internet and OSI define objects uniquely by a tree structure

Each managed object occupies a node in the tree underneath the root

Root

Level 1

Level 2

Level 3

Management Information Tree Managed Objects

Standard organizations: definemanagement of objects under them

iso-itu2

itu0

iso1

org3

dod6

internet1

OSI Management Information Tree

Designation of objects: iso 1 org 1.3 dod 1.3.6 internet

1.3.6.1

Object Type and Instance

object ID unique ID

and descriptor and name for the object

syntax used to model the object

access access privilege to a managed

object (read-only, etc)

status implementation requirements (e.g., optional or mandatory)

definition textual description of the

semantics of object type

Object Type:Object ID and

Descriptorcircle

Access:Access

privilege

Definition:Semantics -

textual description

Status:Implementationrequirements

Syntax :model of object

Internet Perspective

Object Type and Instance

object class managed object

attributes attributes visible at its boundary

operations access operations that can be applied to it

behavior behavior exhibited by it in response to an operation

Notifications notifications emitted by the object

Behavior

Object Class:Circularobject

Ob

ject

Cla

ss:

Elli

ptic

al

ob

ject

Attributes::

circle, dimension

Operations:

Push

Attributes:ellipse, dimension

Notifications:

Notify changes in attribute values

OSI Perspective

Object Type and Instance

Characteristics Example

Object type PktCounter

Syntax Counter

Access Read-only

Status Mandatory

Description Counts number of packets

Internet Perspective

Characteristics Example

Object class Packet Counter

Attributes Single-valued

Operations get, set

Behavior Retrieves or resets values

Notifications Generates notifications on new value

OSI Perspective

Packet Counter As Example of Managed Object

Functional Model

Configuration management Set and change network

configuration and component parameters

Set up alarm thresholds Fault management

Detection and isolation of failures in network

Trouble ticket administration Performance management

Monitor performance of network

Security management Authentication Authorization Encryption

Accounting management Functional accounting of network

usage