5-8
Catalyst 3550 Multilayer Switch Software Configuration Guide
78-11194-03
Chapter5 Clustering Switches
Planning a Switch Cluster
Discovery through the Same Management VLAN
When the cluster has a Catalyst2900 XL, Catalyst2950, or Catalyst 3500 XL command switch, all
cluster members must connect to it through the command-swit ch management VLAN, which is VLAN1
by default. If the cluster members include Catalyst3550 switches, these member switches must also be
connected to the command-switch management VLAN. For i nformation about management VLANs on
these switches, refer to the software configuration guide for that specific switch.
To avoid this limitation, assign a Catalyst3550 switch as the command switch whenever possible. A
Catalyst 3550 command switch can manage these cluster members even if they belong to different
management VLANs (see the “Discovery through Different Management VLANs” sect ion on page5-9).
The command switch in Figure5-4 h as ports assigned to management VLAN9. It discovers all but t hese
switches:
Switches 7 and 10 because their management VLAN (VLAN 4) is different from the
command-switch management VLAN (VLAN9)
Switch 9 because automatic discovery does not extend beyond a noncandidate device, which is
switch 7
Figure5-4 Discovery through the Same Management VLAN
Catalyst 1900,
Catalyst 2820,
Catalyst 2900 XL,
Catalyst 2950, and
Catalyst 3500 XL
switches
VLAN 9
VLAN trunk 4, 9
VLAN 9
VLAN 9
VLAN 9
VLAN 9 VLAN 9
Standby command switchCommand switch
VLAN 9
Switch 7
(management
VLAN 4)
Switch 9
(management
VLAN 9)
VLAN 4
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Catalyst 2900 XL, Catalyst 2950,
or Catalyst 3500 XL command
and standby command switches
Switch 3
(management
VLAN 9)
Switch 4
(management
VLAN 9)
Switch 10
(management
VLAN 4)
Switch 8
(management
VLAN 9)
Switch 6
(management
VLAN 9)
Switch 5
(management
VLAN 9)