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Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
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Chapter 6 Clustering Switches
Planning a Switch Cluster
Discovery Through Different VLANs
If the cluster command switch is a Catalyst 2940, Catalyst 2950, Catalyst 2955, or Catalyst 3550 switch,
the cluster can have cluster member switches in different VLANs. As cluster member switches, they
must be connected through at least one VLAN in common with the cluster command switch. The cluster
command switch in Figure 6-3 has ports assigned to VLANs 9, 16, and 62 and therefore discovers the
switches in those VLANs. It does not discover the switch in VLAN 50. It also does not discover the
switch in VLAN 16 in the first column because the cluster command switch has no VLAN connectivity
to it.
Catalyst 2900 XL, Catalyst 2950, and Catalyst 3500 XL cluster member switches must be connected to
the cluster command switch through their management VLAN. For information about discovery through
management VLANs, see the “Discovery Through Different Management VLANs” section on page 6-7.
For more information about VLANs, see Chapter 16, “Configuring VLANs.”
Figure 6-3 Discovery Through Different VLANs
Discovery Through Different Management VLANs
Catalyst cluster command switches can discover and manage cluster member switches in different
VLANs and different management VLANs. As cluster member switches, they must be connected
through at least one VLAN in common with the cluster command switch. They do not need to be
connected to the cluster command switch through their management VLAN. The default management
VLAN is VLAN 1.
The cluster command switch and standby command switch in Figure 6-4 (assuming they are
Catalyst cluster command switches) have ports assigned to VLANs 9, 16, and 62. The management
VLAN on the cluster command switch is VLAN 9. Each cluster command switch discovers the switches
in the different management VLANs except these:
Switches 7 and 10 (switches in management VLAN 4) because they are not connected through a
common VLAN (meaning VLANs 62 and 9) with the cluster command switch
VLAN 62
VLAN 62
VLAN 16
VLAN trunk 9,16
Command device
VLAN 50
VLAN trunk 9,16
VLAN trunk 4,16
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