Cisco Systems 3750E manual Automatic Recovery of Cluster Configuration

Chapter 6 Clustering Switches

Planning a Switch Cluster

•All standby-group members must be members of the cluster.

Note There is no limit to the number of switches that you can assign as standby cluster command switches. However, the total number of switches in the cluster—which would include the active cluster command switch, standby-group members, and cluster member switches—cannot be more than 16.

•Each standby-group member (Figure 6-7) must be connected to the cluster command switch through the same VLAN. In this example, the cluster command switch and standby cluster command switches are Catalyst 3560-E or Catalyst 3750-E cluster command switches. Each standby-group member must also be redundantly connected to each other through at least one VLAN in common with the switch cluster.

Catalyst 1900, Catalyst 2820, Catalyst 2900 XL, Catalyst 2950, and Catalyst 3500 XL cluster member switches must be connected to the cluster standby group through their management VLANs. For more information about VLANs in switch clusters, see these sections:

–“Discovery Through Different VLANs” section on page 6-7

–“Discovery Through Different Management VLANs” section on page 6-8

Figure 6-7 VLAN Connectivity between Standby-Group Members and Cluster Members

	Command			Passive
		device		command device
			VLANs 9,16	VLANs 9,16
VLAN 9

Management	VLAN 9	Management
VLAN 9		VLAN 16

Member devices

Standby

command device

Management

VLAN 16

VLAN 16

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Automatic Recovery of Cluster Configuration

The active cluster command switch continually forwards cluster-configuration information (but not device-configuration information) to the standby cluster command switch. This ensures that the standby cluster command switch can take over the cluster immediately after the active cluster command switch fails.

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

OL-9775-02 6-13