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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter 6 Clustering Switches
Planning a Switch Cluster
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When the command switch is a Catalyst 2950 LRE switch, all standby command switches must
be Catalyst 2950 LRE switches.
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When the command switch is a non-LRE Catalyst 2950 switch running Cisco IOS
Release 12.1(9)EA1 or later, all standby command switches must be non-LRE Catalyst 2950
switches running Cisco IOS Release 12.1(9)EA1 or later.
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When the command switch is a non-LRE Catalyst 2950 switch running Cisco IOS
Release 12.1(6)EA2 or later, all standby command switches must be non-LRE Catalyst 2950
switches running Cisco IOS Release 12.1(6)EA2 or later.
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When the command switch is running Cisco IOS Release 12.0(5)WC2 or earlier, the standby
command switches can be these switches: Catalyst 2900 XL, non-LRE Catalyst 2950, and
Catalyst 3500 XL switches.
We strongly recommend that the command switch and standby command switches are of the same
switch platform.
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If you have a Catalyst 3550 command switch, the standby command switches should be
Catalyst 3550 switches.
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If you have a Catalyst 2955 command switch, the standby command switches should be
Catalyst 2955 switches.
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If you have a Catalyst 2950 LRE command switch, the standby command switches should be
Catalyst 2950 LRE switches.
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If you have a non-LRE Catalyst 2950 command switch, the standby command switches should
be non-LRE Catalyst 2950 switches.
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If you have a Catalyst 2900 XL or Catalyst 3500 XL command switch, the standby command
switches should be Catalyst 2900 XL and Catalyst 3500 XL switches.
•
Only one cluster standby group can be assigned to a cluster. You can have more than one
router-redundancy standby group.
An HSRP group can be both a cluster standby group and a router-redundancy group. However, if a
router-redundancy group becomes a cluster standby group, router redundancy becomes disabled on
that group. You can reenable it by using the CLI. For more information about HSRP and router
redundancy, see
Chapter 32, “Configuring HSRP.”
•
All standby-group members must be members of the cluster.
Note
There is no limit to the number of switches that you can assign as standby command
switches. However, the total number of switches in the cluster—which would include the
active command switch, standby-group members, and member switches—cannot be more
than 16.
•
Each standby-group member (
) must be connected to the command switch through the
same VLAN. Each standby-group member must also be redundantly connected to each other
through at least one VLAN in common with the switch cluster.
Catalyst 1900, Catalyst 2820, Catalyst 2900 XL, Catalyst 2940, Catalyst 2950, Catalyst 2955, and
Catalyst 3500 XL member switches must be connected to the cluster standby group through their
management VLANs.For more information about VLANs in switch clusters, see these sections:
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“Discovery through Different VLANs” section on page 6-7
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“Discovery through the Same Management VLAN” section on page 6-8
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“Discovery through Different Management VLANs” section on page 6-9