6-3
Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
78-11380-12
Chapter 6      Clustering Switches
    Understanding Switch Clusters
• A Catalyst 2950 LRE standby command switch is connected to other standby switches through its 
management VLAN and to all member switches through a common VLAN.
• If a non-LRE Catalyst 2950 standby command switch is running Cisco IOS Release 12.1(9)EA1 or 
later, it is connected to other standby switches through its management VLAN and to all member 
switches through a common VLAN.
• If a non-LRE Catalyst 2950 standby command switch is running a release earlier than Cisco IOS 
Release 12.1(9)EA1, it is connected to the command switch and to other standby command switches 
and member switches through its management VLAN.
Note Non-LRE Catalyst 2950 command switches running Cisco IOS Release 12.1(9)EA1 or later 
can connect to standby command switches in the management VLAN. 
• It is redundantly connected to the cluster so that connectivity to member switches is maintained.
• It is not a command or member switch of another cluster.
Note Standby cluster command switches must be the same type of switches as the cluster 
command switch. For example, if the cluster command switch is a Catalyst 2955 switch, the 
standby cluster command switches must also be Catalyst 2955 switches. 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.
Candidate Switch and Member Switch Characteristics
Candidate switches are cluster-capable switches that have not yet been added to a cluster. Member 
switches are switches that have actually been added to a switch cluster. Although not required, a 
candidate or member switch can have its own IP address and password.
To join a cluster, a candidate switch must meet these requirements:
• It is running cluster-capable software.
• It has CDP Version 2 enabled.
• It is not a command or member switch of another cluster.
• A Catalyst 2950 LRE or Catalyst 2955 member or candidate switch is connected to the command 
switch through at least one common VLAN.
• If a non-LRE Catalyst 2950 member or candidate switch is running Cisco IOS Release 12.1(9)EA1 
or later, it is connected to the command switch through at least one common VLAN.
• If a non-LRE Catalyst 2950 member or candidate switch is running a release earlier than Cisco IOS 
Release 12.1(9)EA1, it is connected to the command switch through the command-switch 
management VLAN.
Note Non-LRE Catalyst 2950 standby command switches running Cisco IOS Release 12.1(9)EA1 
or later can connect to candidate and member switches in VLANs different from their 
management VLANs.