1. SNMP (Simple Network Management Protocol) based Network Management

2. Network Management: What is it?
Network management includes
deployment,integration and coordination of the hardware, software, and human elements
to monitor, test, poll, configure, analyze, evaluate and control the network and element resources
to meet the real-time, operational performance, and Quality of service requirements at a reasonable cost.

3. Network Management: Why is it needed?
Lowers costs by eliminating the need for many administrators at multiple locations performing the same function
Makes network administration and monitoring easier and more convenient
Coherent presentation of data

4. Functional Areas of Network Management (According to OSI Network Management Model)
Performance Management – how smoothly is the network running
Fault Management - reactive and proactive network fault management (deals with problems and emergencies in the network)
Configuration Management – keeping track of device settings and how they function
Accounting Management - cost management and charge back assessment
Security Management - SNMP (Version 1 and 2) doesn’t provide much here

5. N/w Management arch.

6. Network Management Architectures
1) Management Entity job is to provide access to management data, controls, and behaviors:
Regular polling or sampling of management data
the management entity requests updates from managed devices to reflect recent status of the network being managed.
When alerts are received, appropriate responses must be generated

7. Network Management Architectures (contd.)
2) Managed Device
At each managed device, a special piece of software(process) called a management agent responds to polls for collected data,
The management agent itself has custody of a management database (MDB) of information that it collects and maintains over time

8. Network Management Architectures (contd.)
3) N/w Management Protocol
The protocol runs between managing entity and the managed device.
Allows the managing entity to query the status of the managed devices .
Agents can use the network management protocol to inform the managing entity of exceptional events.

9. SNMP & The OSI Model

10. Versions Two major versions SNMPv1, SNMPv2
SNMPv1 is the recommended standard
SNMPv2 has become split into:
SNMPv2u - SNMPv2 with user-based security
SNMPv2* - SNMPv2 with user-based security and additional features
SNMPv2c - SNMPv2 without security
SNMPv3 - Security

11. Client Pull & Server Push
SNMP is a “client pull” model
The management system (client) “pulls” data from the agent (server).
SNMP is a “server push” model
The agent (server) “pushes” out a trap message to a (client) management system

12. The Internet- Standard Management Framework
SNMP is a tool (protocol) that allows for remote and local management of items on the network including servers, workstations, routers, switches and other managed devices.
Comprised of agents and managers
Agent - process running on each managed node collecting information about the device it is running on.
Manager - process running on a management workstation that requests information about devices on the network.

13. The Internet- Standard Management Framework (contd.)
SNMP network management consists of four parts:
Management Information Base (MIB)
A map of the hierarchical order of all managed objects and how they are accessed
Structure of Management Information (SMI)
Rules specifying the format used to define objects managed on the network that the SNMP protocol accesses
SNMP Protocol
Defines format of messages exchanged by management systems and agents.
Specifies the Get, GetNext, Set, and Trap operations
Security and administration capabilities
The addition of these capabilities represents the major enhancement in SNMPv3 over SNMPv2

14. Registered Tree

15. MIB-2 MIB-II Standard Internet MIB
Definition follows structure given in SMI
MIB-II (RFC 1213) is current standard definition of the virtual file store for SNMP manageable objects
Has 10 basic groups
system
interfaces at ip
icmp
tcp
udp
egp
transmission
snmp
If agent implements any group then is has to implement all of the managed objects within that group

16. Ports & UDP
SNMP uses User Datagram Protocol (UDP) as the transport mechanism for SNMP messages
Ethernet Frame
IP Packet
SNMP Message
CRC
UDP Datagram
Like FTP, SNMP uses two well-known ports to operate:
UDP Port SNMP Messages
UDP Port SNMP Trap Messages

17. Four Basic Operations Get GetNext Set Trap
Retrieves the value of a MIB variable stored on the agent machine
(integer, string, or address of another MIB variable)
GetNext
Retrieves the next value of the next lexical MIB variable
Set
Changes the value of a MIB variable
Trap
An unsolicited notification sent by an agent to a management application (typically a notification of something unexpected, like an error)

18. Basic operations contd..
get_request
get_response
port 161
get_next_request
get_response
port 161
Manager
Agent
set_request
set_response
port 161
trap
port 162
port 161

19. Traps
Traps are unrequested event reports that are sent to a management system by an SNMP agent process
When a trappable event occurs, a trap message is generated by the agent and is sent to a trap destination (a specific, configured network address)
Many events can be configured to signal a trap, like a network cable fault, failing NIC or Hard Drive, a “General Protection Fault”, or a power supply failure
Traps can also be throttled -- You can limit the number of traps sent per second from the agent
Traps have a priority associated with them -- Critical, Major, Minor, Warning, Marginal, Informational, Normal, Unknown

20. Trap Receivers
Management applications can handle the trap in a few ways:
Poll the agent that sent the trap for more information about the event, and the status of the rest of the machine.
Log the reception of the trap.
Completely ignore the trap.

21. Languages of SNMP Structure of Management Information (SMI)
specifies the format used for defining managed objects that are accessed via the SNMP protocol
Abstract Syntax Notation One (ASN.1)
used to define the format of SNMP messages and managed objects (MIB modules) using an unambiguous data description format
Basic Encoding Rules (BER)
used to encode the SNMP messages into a format suitable for transmission across a network

22. SNMP MESSAGE ENCODING
The description of MIBs and message formats is based on the ASN.1 syntax.
The mapping from an abstract syntax upon a transfer syntax is defined by BER.

23. Basic Message Format Message Length Message Version Community String
Message Preamble
Community String
PDU Header
SNMP Protocol Data Unit
PDU Body

25. SNMP Agents Two basic designs of agents Extendible Agents
Open, modular design allows for adaptations to new management data and operational requirements
Monolithic Agents
not extendible
optimized for specific hardware platform and OS

26. Community Names
A community string is a password that allows access to a network device. It defines what "community of people" can access the SNMP information that is on the device.
Community names are used to define where an SNMP message is destined for.
Set up your agents to belong to certain communities.
Set up your management applications to monitor and receive traps from certain community names.
There are actually three community strings for SNMP-speaking devices:
The SNMP Read-only community string
The SNMP Read-Write community string
The SNMP Trap community string

27. Proxy Management
A node may not support SNMP, but may be manageable by SNMP through a proxy agent running on another machine.
Nowadays the term proxy denotes a device that forwards SNMP messages, but doesn’t look at the individual objects.

28. Advantages of using SNMP
Standardized
universally supported
extendible
portable
allows distributed management access
lightweight protocol

29. تاریخ امتحان پنج شنبه 7/3/94
ساعت 9
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