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Catalyst 2950 Desktop Switch Software Configuration Guide
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Chapter 6 Clustering Switches
Planning a Sw it ch Cl uster

Host Names

You do not ne ed to assig n a host name to either a c omman d switch or an eligi ble clus ter memb er.
However, a host name assigned to the command switch can help to identify the switch cluster. The
default host name for the switch is Switch.
If a sw itch j oins a cl uster and i t d oes no t have a host name , the comm an d switc h app ends a uniq ue
member number to its own host name and assigns it sequentially as each switch joins the cluster. The
number means the order in which the switch was added to the cluster. For example, a command switch
named eng-cluster coul d name th e fifth cluste r member eng-cluster-5.
If a switch has a host name, it retains that name when it joins a cluster. It retains that host name even
after it leaves the cluster.
If a switch receiv ed its host name from the command switch, was removed from a cluster , was then added
to a new cluster , and kept the same member number (such as 5), the old host name (such as eng-cluster-5)
is overwritten with the host name of the command switch in the new cluster (such as mkg-cluster-5). If
the switch member number changes in the new cluster (such as 3), the switch retains the previous name
(eng-cluster-5).

Passwords

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 member switch inherits a null password. Member switches
only inher it the comm and-s witc h password.
If yo u chang e the mem ber -switch passw ord to be dif fer ent fr om the co mmand- switch passw ord an d sa v e
the change, the switch is not manageable by the command switch until you change the member-switch
password to mat ch t he co mm and-sw it ch pa ssword. Rebo oti ng the m em ber s wit ch d oes not revert the
password b ack to t h e co mm an d-swi tch passwo rd. We rec omm end that you d o n ot cha nge th e
member-s witch password after it joins a cluster.
For more i nform ati on abou t pa sswords, see the “Preventing Unauthorized Access to Your Switch”
section on page 7-1.
For password c on sider ati ons spec ific to the Cat alyst 1 900 and Ca talyst 2820 swit ches, ref er t o the
installation and configuration guides for those switches.

SNMP Community Strings

A member switch inherits the command-switch first read-only (RO) and read-write (RW) community
strings with @esN append ed to the c ommunit y string s:
•command-switch-readonly-community-string@esN, where N is the member-switch number.
•command-switch-readwrite-community-string@esN, wher e N is the membe r-switch number.
If the command switch has multiple read-only or read-write community strings, only the first read-only
and read-write strings are propagated to the member switch.
The switc hes suppo rt an unlimite d number of c ommunit y strings and st ring lengths. For more
inform ation about SNMP and com munit y strings, see Chapter 24, “Co nfiguring SNMP.”
For SNMP considerations specific to the Catalyst 1900 and Catalyst 2820 switches, refer to the
installation and configuration guides specific to those switches.