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Cisco EtherSwitch Service Modules Feature Guide
Information About the Cisco EtherSwitch Service Modules
31
Cisco IOS Release 12.2(25)SEC
Passwords in Clusters
You do not need to assign passwords to an individual switch if it will be a cluster member. When a switch
joins a cluster, it inherits the command-switch password and retains it when it leaves the cluster. If no
command-switch password is configured, the cluster member switch inherits a null password. Cluster
member switches only inherit the command-switch password.
If you change the member-switch password to be different from the command-switch password and save
the change, the switch is not manageable by the cluster command switch until you change the
member-switch password to match the command-switch password. Rebooting the member switch does
not revert the password back to the command-switch password. We recommend that you do not change
the member-switch password after it joins a cluster.
For more information about passwords, see the Catalyst 3750 Switch Software Configuration Guide,
Cisco IOS Release 12.2 at http://www.cisco.com/univercd/cc/td/doc/product/lan/cat3750/index.htm.
SNMP Community Strings in Clusters
A cluster member switch inherits the command-switch first read-only (RO) and read-write (RW)
community strings with @esN appended to the community strings:
• command-switch-readonly-community-string@esN, where N is the member-switch number.
• command-switch-readwrite-community-string@esN, where N is the member-switch number.
If the cluster command switch has multiple read-only or read-write community strings, only the first
read-only and read-write strings are propagated to the cluster member switch.
The switches support an unlimited number of community strings and string lengths. For more
information about SNMP and community strings, see the Catalyst 3750 Switch Software Configuration
Guide, Cisco IOS Release 12.2 at
http://www.cisco.com/univercd/cc/td/doc/product/lan/cat3750/index.htm.
For SNMP considerations specific to the Catalyst 1900 and Catalyst 2820 switches, see the installation
and configuration guides specific to those switches.
Switch Clusters and Switch Stacks
A switch cluster can have one or more Cisco EtherSwitch service module switch stacks. Each switch
stack can act as the cluster command switch or as a single cluster member. Table 1 describes the basic
differences between switch stacks and switch clusters. For more information about switch stacks, see the
Catalyst 3750 Switch Software Configuration Guide, Cisco IOS Release 12.2 at
http://www.cisco.com/univercd/cc/td/doc/product/lan/cat3750/index.htm.
Table 1 Basic Comparison of Switch Stacks and Switch Clusters
Switch Stack Switch Cluster
A switch stack is made up of Cisco EtherSwitch service
modules or Catalyst 3750 switches.
A switch cluster is made up of cluster-capable devices, such
as the Cisco EtherSwitch service module or Catalyst 3750
switch.
Stack members are connected through Cisco StackWise ports. Cluster members are connected through LAN ports.
A switch stack requires 1 stack master and supports up to 8
other stack members.
A switch cluster requires 1 cluster command switch and
supports up to 15 other cluster member switches.