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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
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Configuring SNMP
This chapter describes how to configure the Simple Network Management Protocol (SNMP) on the
Catalyst 3750-X or 3560-X switch. Unless otherwise noted, the term switch refers to a Catalyst 3750-X
or 3560-X standalone switch and to a Catalyst 3750-X switch stack.
Note For complete syntax and usage information for the commands used in this chapter, see the command
reference for this release and the Cisco IOS Network Management Command Reference, Release 12.4
from the Cisco.com page at this URL:
http://www.cisco.com/en/US/docs/ios/netmgmt/command/reference/nm_book.html
• Understanding SNMP, page 35-1
• Configuring SNMP, page 35-6
• Displaying SNMP Status, page 35-19

Understanding SNMP

SNMP is an application-layer protocol that provides a message format for communication between
managers and agents. The SNMP system consists of an SNMP manager, an SNMP agent, and a MIB.
The SNMP manager can be part of a network management system (NMS) such as CiscoWorks. The agent
and MIB reside on the switch. To configure SNMP on the switch, you define the relationship between
the manager and the agent.
The SNMP agent contains MIB variables whose values the SNMP manager can request or change. A
manager can get a value from an agent or store a value into the agent. The agent gathers data from the
MIB, the repository for information about device parameters and network data. The agent can also
respond to a manager’s requests to get or set data.
An agent can send unsolicited traps to the manager. Traps are messages alerting the SNMP manager to
a condition on the network. Traps can mean improper user authentication, restarts, link status (up or
down), MAC address tracking, closing of a TCP connection, loss of connection to a neighbor, or other
significant events.
On the Catalyst 3750-X switch, the stack master handles the SNMP requests and traps for the whole
switch stack. The stack master transparently manages any requests or traps that are related to all stack
members. When a new stack master is elected, the new master continues to handle SNMP requests and
traps as configured on the previous stack master, assuming that IP connectivity to the SNMP
management stations is still in place after the new master has taken control.
For more information about switch stacks, see Chapter 5, “Managing Switch Stacks.”