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Catalyst 2940 Switch Software Configuration Guide
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Chapter5 Clustering Switches Planning a Switch Cluster
Discovery Through Non-CDP-Capable and Noncluster-Capable Devices
If a command switch is connected to a non-CDP-capable third-party hub (such as a non-Cisco hub), it
can discover cluster-enabled devices connected to that third-party hub. Ho we ver , if the command switch
is connected to a noncluster-capable Cisco device, it cannot discover a cluster-enabled device connected
beyond the noncluster-capable Cisco device.
Figure 5-2 shows that the command switch discovers the Catalyst3500 XL switch, which is connected
to a third-party hub. However, the command switch does not discover the Catalyst 2940 switch tha t i s
connected to a Catalyst 5000 switch.
Refer to the release notes for the Catalyst switches that can be part of a switch cluster.
Figure5-2 Discovery Through Non-CDP-Capable and Noncluster-Capable Devices
Discovery Through the Same Management VLAN
A Catalyst 2900XL command switch, a Catalyst 2950 comma nd switch ru nning a rele ase ea rlier th an
Cisco IOS Release 12.1(9)EA1, or a Catalyst3500 XL command switch must connect to all cluster
members through its management VLAN. The default management V LAN is VLA N 1. For more
information about management VLANs, see the “Management VLAN” sectio n on pa ge 5-14.
Note You can avoid this limitation by using, whenever possible, a Catalyst35 50 command switch, a Catalyst
2950 command switch running Cisco IOS Release 12.1(9)EA1 or later, or a Catalyst 2940 command
switch. These command switches can manage cluster members even if they belong to different
management VLANs. See the “Discovery Through Different Management VLANs” section on page 5-6.
The command switch in Figure 5-3 has ports assigned to management VLAN 9. It discovers all but these
switches:
Switches 7 and 10 because their management VLAN (VLAN4) 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
Command switch
Catalyst 5000 switch
(noncluster-capable)
Third-party hub
(non-CDP-capable)
Catalyst 3500 XL
candidate switch
Catalyst 2940
candidate switch
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