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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
etR
equ
est
Ge
tNe
xtR
eq
uest
Se
tReq
ues
t
Ge
tRe
spo
nse
Tra
p
Layer 1 & 2
IP
SNMP Manager
UDP
Layer 1 & 2
IP
SNMP Agent
UDP
NetworkG
etR
equ
est
Ge
tNe
xtR
eq
uest
Se
tReq
ues
t
Ge
tRe
spo
nse
Tra
p
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