Cisco Systems 3750E manual Switch Clusters and Switch Stacks, Switch Stack Switch Cluster

Chapter 6 Clustering Switches

Planning a Switch Cluster

Switch Clusters and Switch Stacks

A switch cluster can have one or more Catalyst 3750-E switch stacks. Each switch stack can act as the cluster command switch or as a single cluster member. Table 6-2describes the basic differences between switch stacks and switch clusters. For more information about switch stacks, see Chapter 5, “Managing Switch Stacks.”

Table 6-2 Basic Comparison of Switch Stacks and Switch Clusters

Switch Stack	Switch Cluster
Made up of Catalyst 3750-E switches only	Made up of cluster-capable switches, such as
	Catalyst 3750-E, Catalyst 3560-E, Catalyst 3750, and
	Catalyst 2950 switches
Stack members are connected through StackWise Plus ports	Cluster members are connected through LAN ports
Requires one stack master and supports up to eight other stack	Requires 1 cluster command switch and supports up to
members	15 other cluster member switches
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	Cluster command switch is the single point of some manage-
all stack members in a particular switch stack	ment for all cluster members in a particular switch cluster
Back-up stack master is automatically determined in case the	Standby cluster command switch must be pre-assigned in case
stack master fails	the cluster command switch fails
Switch stack supports up to eight simultaneous stack master	Switch cluster supports only one cluster command switch
failures	failure at a time
Stack members (as a switch stack) behave and is presented as	Cluster members are various, independent switches that are
a single, unified system in the network	not managed as and do not behave as a unified system
Integrated management of stack members through a single	Cluster members have separate, individual configuration files
configuration file
Stack- and interface-level configurations are stored on each	Cluster configuration are stored on the cluster command
stack member	switch and the standby cluster command switch
New stack members are automatically added to the switch	New cluster members must be manually added to the switch
stack	cluster

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.

Catalyst 3750-E and 3560-E Switch Software Configuration Guide

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