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Chapter 6 Clustering Switches
Using SNMP to Manage Switch Clusters

Using SNMP to Manage Switc h Clusters

When you f irst power on the switch, SNMP is enabled if you enter the IP information by using the setup
program a nd a ccep t i ts p rop ose d con figurat ion. If y ou did not use the setup p rog ram to e nte r th e IP
inform ation a nd SNMP was not enab led, you ca n enabl e it as describe d in the “Configuri ng SNMP”
section on page 24-5. O n Catalyst 19 00 and Catalyst 2820 switch es, SNMP is enab led by default.
When you create a cluster, the command switch manages the exchange of messages between member
switches and an SNMP application. The cluster software on the command switch appends the member
switch numbe r (@esN, where N is the switch number) to the first configured read-write and read-only
comm unity st rings on t he c om ma nd swi tch and pro pa gate s t hem t o th e mem ber sw it ch. Th e co mman d
switch uses this community string to control the forwarding of gets, sets, and get-next messages between
the SNM P mana gem ent stati on a nd the mem ber switc hes.
Note Whe n a clust er st andby group is c onfigured , the com ma nd switc h can ch an ge wit hou t your knowledge.
Use the first read-write and read-only community strings to communicate with the command switch if
there is a clust er stan dby group configured for the cluster.
If the mem ber swi tch does no t ha v e an IP add ress, the com mand s witch red irects trap s fro m the mem ber
switch to th e mana ge ment st at ion, as sh own in Figure 6-15. If a member switch has its own IP address
and commu nity str ings, the membe r switch c an send traps dire ctly to th e manageme nt station, without
going thr ough the c omman d switch.
If a m emb er switc h has i ts own I P a ddr ess a nd co mmuni ty stri ngs, t h ey can be u s ed i n addi tio n to the
acces s provided b y the command swit ch. For more inf ormation about SNMP and commu nity strings , see
Chapter 24, “Configuring SNMP.”
Figure 6-15 SNMP Management for a Cluster
Trap
Trap
Trap
Command switch
Trap 1, Trap 2, Trap 3
Member 1 Member 2 Member 3
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SNMP Manager