SNMP

Simple Network Management Protocol

Exchange management information between network devices

• Each Managed Device, a host or a router, maintains a number of Management Information Bases (MIBs)
• Each managed device has an SNMP Agent to provide interface between MIBs and an SNMP Manager
• An SNMP manager, usually implemented in Network Management System (NMS), can work with multiple SNMP agents
• Uses well-known UDP port number 161/162 at the agent/manager

SNMP Message Format

• Community Name
  • Access scope for SNMP managers and agents
  • A different community name will be discarded
• Protocol Data Unit (PDU) Type specifies the SNMP message type
• Request ID: match an SNMP request with the corresponding response

MIB (Management Information Bases)

A managed device maintains a large number of SNMP objects to store management information. The Structure of Management Information (SMI) defines the rules for describing management information and the data types used in SNMP.

• Tree Structure
  • Each level of the tree consists of groups
  • Each group has its name and the associated numerical identifier
  • Leaves in the mib-2 subtree are MIB objects

Here is an example for MIB Tree Structure:

The leaf tcpMaxConn can be defined as 1.3.6.1.2.1.6.4 or iso.org.dod.internet.mgmt.mib-2.tcp.tcpMaxConn.