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Catalyst 2950 Desktop Switch Software Configuration Guide
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Chapter 24 Configuring SNMP Configuring SNMP

SNMP Notifications

SNMP allows the switch to send notifications to SNMP managers when particular events occur. SNMP
notifications can be sent as traps or inform requests. In command syntax, unless there is an option in the
command to select eith er traps or informs, the keyword traps refe rs to eithe r traps or in forms, or bot h.
Use the snmp-server host co mman d to specify whether to send SNMP notifications as trap s o r in for ms.
Traps are unreliable because the receiver does not send an acknowledgment when it receives a trap, and
the sender cannot determine if the trap was received. When an SNMP manager receives an inform
request, i t acknowledges the messa ge with an SNMP re sponse pr otocol data unit (PDU). If the se nder
does not receive a response, the inform request can be sent again. Because they can be re-sent, informs
are more likely than traps to reach their intended destination.
The charact eristics that make informs more reliable than traps also consume more resources in the switch
and in t he n et work. U nli ke a t rap, w hich i s disca r ded as s oon a s i t i s sen t, a n info rm r equ es t i s h eld i n
memory until a response is received or the request times out. Traps are sent only once, but an inform
might be re-sen t or retrie d several times. T he retrie s incre ase traffic and co ntribute to a higher overhead
on the network. Ther efore, traps and informs require a trade-off be tween re liability and resources. If it
is importa nt that the SNMP mana ger rece ive ever y notificatio n, use infor m request s. If traffic on the
network or memory in the switch is a concern and notification is not required, use traps.
Note SNMPv 1 d oes n ot su ppor t inf orm s.

Configuring SNMP

This se ction de scribe s how to configure SNMP on yo ur switch. I t c ontai ns th is c onfigurati on
information:
•Default SNMP Con figuration, page 24-6
•SNMP Configuration Gu idelines, page 24-6
•Disabling the SNMP Agent, page 24-7
•Configuring Co mmuni ty Strings, pag e 24- 7
•Configuring SNM P Groups and Use rs, pag e 24-8
•Configuring SN MP N oti fications, pa ge 2 4-1 0
•Setting the Agent Contact and Location Information , page 24-13
•Limiting TFTP Servers Use d Through SN MP, page 24-1 3
•SNMP Exam ples, pa ge 24-14