Chapter 6 Clustering Switche; Understanding Switch Clusters - Cisco WS-C3750-48PS-S Software Configuration Manual

Understanding Switch Clusters

Understanding Switch Clusters
A switch cluster is a set of up to 16 connected, cluster-capable Catalyst switches that are managed as a
single entity. The switches in the cluster use the switch clustering technology so that you can configure
and troubleshoot a group of different Catalyst desktop switch platforms through a single IP address.
In a switch cluster, 1 switch must be the cluster command switch and up to 15 other switches can be
cluster member switches. The total number of switches in a cluster cannot exceed 16 switches. The
cluster command switch is the single point of access used to configure, manage, and monitor the cluster
member switches. Cluster members can belong to only one cluster at a time.
A switch cluster is different from a switch stack. A switch stack is a set of Catalyst 3750 switches
Note
connected through their stack ports. For more information about how switch stacks differ from switch
clusters, see the
The benefits of clustering switches include:
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Refer to the release notes for the list of Catalyst switches eligible for switch clustering, including which
ones can be cluster command switches and which ones can only be cluster member switches, and the
required software versions.
These sections describe:
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Catalyst 3750 Switch Software Configuration Guide
6-2
"Switch Clusters and Switch Stacks" section on page
Management of Catalyst switches regardless of their interconnection media and their physical
locations. The switches can be in the same location, or they can be distributed across a Layer 2 or
Layer 3 (if your cluster is using a Catalyst 3550, Catalyst 3560, or Catalyst 3750 switch as a Layer 3
router between the Layer 2 switches in the cluster) network.
Cluster members are connected to the cluster command switch according to the connectivity
guidelines described in the
page 6-5. This section includes management VLAN considerations for the Catalyst 1900,
Catalyst 2820, Catalyst 2900 XL, Catalyst 2950, and Catalyst 3500 XL switches. For complete
information about these switches in a switch-cluster environment, refer to the software
configuration guide for that specific switch.
Command-switch redundancy if a cluster command switch fails. One or more switches can be
designated as standby cluster command switches to avoid loss of contact with cluster members. A
cluster standby group is a group of standby cluster command switches.
Management of a variety of Catalyst switches through a single IP address. This conserves on IP
addresses, especially if you have a limited number of them. All communication with the switch
cluster is through the cluster command switch IP address.
Cluster Command Switch Characteristics, page 6-3
Standby Cluster Command Switch Characteristics, page 6-3
Candidate Switch and Cluster Member Switch Characteristics, page 6-4
"Automatic Discovery of Cluster Candidates and Members" section on
Chapter 6 Clustering Switches
6-14.
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