5-8
Catalyst 3550 Multilayer Switch Software Configuration Guide
78-11194-03
Chapter 5 Clustering Switches
Planning a Switch Cluster
Discovery through the Same Management VLAN
When the cluster has a Catalyst 2900 XL, Catalyst 2950, or Catalyst 3500 XL command switch, all
cluster members must connect to it through the command-switch management VLAN, which is VLAN 1
by default. If the cluster members include Catalyst 3550 switches, these member switches must also be
connected to the command-switch management VLAN. For information about management VLANs on
these switches, refer to the software configuration guide for that specific switch.
To avoid this limitation, assign a Catalyst 3550 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” section on page 5-9
).
The command switch in
Figure 5-4
has ports assigned to management VLAN 9. It discovers all but these
switches:
•
Switches 7 and 10 because their management VLAN (VLAN 4) is different from the
command-switch management VLAN (VLAN 9)
•
Switch 9 because automatic discovery does not extend beyond a noncandidate device, which is
switch 7
Figure 5-4
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 switch
Command switch
VLAN 9
Switch 7
(management
VLAN 4)
Switch 9
(management
VLAN 9)
VLAN 4
65277
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)