Cisco Catalyst 2960 Software Configuration Manual page 178

Planning a Switch Cluster
Table 6-2 Basic Comparison of Switch Stacks and Switch Clusters
Switch Stack
Made up of Catalyst 2960-S switches only
Stack members are connected through StackWise ports
Requires one stack master and supports up to four other stack
members
Can be a cluster command switch or a cluster member switch Cannot be a stack master or stack member
Stack master is the single point of complete management for
all stack members in a particular switch stack
Back-up stack master is automatically determined in case the
stack master fails
Switch stack supports up to four simultaneous stack master
failures
Stack members (as a switch stack) behave and is presented as
a single, unified system in the network
Integrated management of stack members through a single
configuration file
Stack- and interface-level configurations are stored on each
stack member
New stack members are automatically added to the switch
stack
Recall that stack members work together to behave as a unified system (as a single switch stack) in the
network and are presented to the network as such by Layer 2 and Layer 3 protocols. Therefore, the
switch cluster recognizes switch stacks, not individual stack members, as eligible cluster members.
Individual stack members cannot join a switch cluster or participate as separate cluster members.
Because a switch cluster must have 1 cluster command switch and can have up to 15 cluster members, a
cluster can potentially have up to 16 switch stacks, totalling 144 devices.
Cluster configuration of switch stacks is through the stack master.
These are considerations to keep in mind when you have switch stacks in switch clusters:
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Catalyst 2960 and 2960-S Switches Software Configuration Guide, Release 15.0(1)SE
6-14
If the cluster command switch is not a Catalyst 2960-S switch or switch stack and a new stack master
is elected in a cluster member switch stack, the switch stack loses its connectivity to the switch
cluster if there are no redundant connections between the switch stack and the cluster command
switch. You must add the switch stack to the switch cluster.
If the cluster command switch is a switch stack and new stack masters are simultaneously elected in
the cluster command switch stack and in cluster member switch stacks, connectivity between the
switch stacks is lost if there are no redundant connections between the switch stack and the cluster
command switch. You must add the switch stacks to the cluster, including the cluster command
switch stack.
Switch Cluster
Made up of cluster-capable switches, such as Catalyst 3750,
Catalyst 3550, and Catalyst 2960-S switches
Cluster members are connected through LAN ports
Requires 1 cluster command switch and supports up to
15 other cluster member switches
Cluster command switch is the single point of some
management for all cluster members in a particular switch
cluster
Standby cluster command switch must be pre-assigned in case
the cluster command switch fails
Switch cluster supports only one cluster command switch
failure at a time
Cluster members are various, independent switches that are
not managed as and do not behave as a unified system
Cluster members have separate, individual configuration files
Cluster configuration are stored on the cluster command
switch and the standby cluster command switch
New cluster members must be manually added to the switch
cluster
Chapter 6 Clustering Switches
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