In the Name of the Most High
Fundamentals of Network Management
by
Behzad Akbari
Fall 2011
Network Management Standards

OSI
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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

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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 (…)
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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
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This architecture is used for both OSI and SNMPbased management
Consists of a number of models
OSI Models
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Organization
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Network management components
Functions of components
Relationships
Information
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Structure of Management Information (SMI)
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Management Information Base (MIB)
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Organization of management information
Communication
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Syntax and semantics
Transfer syntax with bi-directional messages
Transfer structure (PDU)
Functions

Application functions

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Configure components
Monitor components
Measure performance
Secure information
Usage accounting
SNMP Architecture and Models

Organization

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Information

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Same as OSI, but scalar
Communication

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Same as OSI model
Messages less complex than OSI and unidirectional
Transfer structure (PDU)
Functions

Application functions
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Operations
Administration
Security
Organizational Model
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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

hubs, bridges, routers,
transmission facilities
Software (non-physical)
programs, algorithms
Managed objects
Administrative information
Unmanaged objects
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
contact person, name of group of
objects (IP group)
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Houses SNMP management agent
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Objects are classified into
managed/unmanaged

Manager
Network elements (hardware,
system)
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
MDB
Managed object has a running
management agent
MDB Management Database
Agent process
Two-Tier Network Management Organization Model
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
MDB
Manager
Managed objects
Unmanaged objects
MDB Management Database
Agent process
Two-Tier Network Management Organization Model
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
MDB
Manager
Managed objects
Unmanaged objects
MDB Management Database
Agent process
Two-Tier Network Management Organization Model
Organization Model

Middle layer plays the dual role

Agent to the top-level manager
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Manager to the managed objects
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collects, processes and stores data
locally
Performs statistical operation on
the data and passes it to top level
manager
MDB
Manager
MDB
Agent / Manager
Managed objects
The intermediate system could be
at a local site and passes info. to a
remote site.
Example of middle level: Remote
monitoring agent (RMON)
MDB Management Database
Agent process
Three-Tier Network Management Organization Model
Organization Model
MoM Manager of Managers
NMS Network Management System
MoM
MDB
Agent
Agent NMS
Agent
MDB
Manager
Managed objects
Agent NMS
MDB
Manager
Managed objects
Different network domains, each managed locally

Agent NMS manages the domain
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MoM presents integrated view of domains

Domain may be geographical, administrative, vendor-specific
products, etc.
Peer NMSs
Agent NMS
Manager NMS
Manager NMS
Agent NMS
Dual Role of Management Process
Figure 3.5 Dual Role of Management Process
Communication Model
SNMP
MANAGER

MIB
AGENT
Resources are represented as objects (or data
variables)


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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
Communication Model
SNMP
MANAGER


MIB
AGENT
Management stations and agents are linked by a network
management protocol
SNMP is used for the management of TCP/IP networks
o
o
o
Get: manager or management station can retrieve the value of
objects at the agent
Set: set the values of objects at the agent
Trap: agent notifies manager on significant events
Protocol Architecture
Management station
Network
manager
Host
Agent
process
Agent
process
Manager process
SNMP
-SNMP uses UDP
port 161
- connection-less
Central
MIB
UDP
TCP
UDP
Router
Agent
process
Agent
process
FTP, etc.
SNMP
SNMP
TCP
UDP
UDP
UDP
UDP
UDP
(e.g., Ethernet, X.25, ATM)
Agent
Userprocess
process
SNMP
FTP, etc.
SNMP
Network-dependent protocols
Host
Agent
process
Agent
process
SNMP
IP
IP
Network-dependent
protocols
Agent
Userprocess
process
Internetwork
Internetwork
IP
Network-dependent protocols
UDP
UDP
IP
Network-dependent
protocols
Interprets SNMP
messages
and controls the
agent’s MIB
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)
Operations /
Requests
Manager
Applications
Responses
Agent
Notifications /
Traps
Network Elements
Managed Objects
Management Message Communication Model
Communication Model
SNMP Manager
Application
SNMP Messages
SNMP Agent
UDP
UDP
IP
IP
Layer 1 & 2
Network
Trap
GetResponse
Central
MIB
SetRequest
manages object
GetNextRequest
SNMP managed
objects
GetRequest
Trap
GetResponse
SetRequest
GetNextRequest
GetRequest
Management
application
Layer 1 & 2
Trap-Directed Polling

SNMP encourages the
manager to use trapdirected polling


managing entity
A manager may be
managing
data
responsible for a large
entity
number agents, each
maintains a large number of
network
managed objects
management
It is impractical to regularly
protocol
poll all agents for all their
readable objects
(management overhead on
agent data
the network may be very
excessive!)
managed device
agent data
managed device
agent data
managed device
agent data
managed device
Trap-Directed Polling

Initially a manager may poll
all the agents for some key
managing entity
information
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e.g., interface characteristicsmanaging
data
(# pckts in/out, etc..)
entity
Then, each agent is
responsible for notifying
network
(through trap messages) the management
protocol
manager of any unusual
event

e.g., high pckt drop rate at
some interface
agent data
managed device
agent data
managed device
agent data
agent data
managed device
managed device
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)
Example
sysDescr:
{ system 1 }
Syntax:
OCTET STRING
Definition: "A textual
description of the entity. "
Access:
read-only
Status:
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

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MDB
Manager
MIB virtual database; schema compiled into
management software

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Contains measured or administratively
configured values of NEs
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
Managed objects
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
 Designation of objects:
iso
org
dod
internet
1
1.3
1.3.6
1.3.6.1
Root
itu
0
Level 1
Level 2
Standard organizations: define
management of objects under them
iso-itu
2
org
3
dod
6
Level 3
Management Information Tree
iso
1
Managed Objects
internet
1
OSI Management Information Tree
Object Type and Instance
Access:
Access
privilege
object ID
unique ID
Object Type:
Object ID and
Descriptor
circle
and descriptor and name for the object
syntax
used to model the object
access
access privilege to a managed
Status :
Implementation
requirements
object (read-only, etc)
status
implementation requirements
(e.g., optional or mandatory)
definition
textual description of the
semantics of object type
Syntax :
model of object
Definition:
Semantics textual description
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
Object Class:
Circular
object
Operations:
Push
:
Attributes:
circle, dimension
Behavior
Object Class:
Elliptical
object
Notifications
:
Notify changes in
attribute values
Attributes:
ellipse, dimension
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

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
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Detection and isolation of failures
in network
Trouble ticket administration
Performance management

Monitor performance of network
Security management



Fault management


Set and change network
configuration and component
parameters
Set up alarm thresholds

Authentication
Authorization
Encryption
Accounting management

Functional accounting of network
usage