Cisco Systems 3130 User Manual

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Cisco Catalyst Blade Switch 3130 for Dell Software Configuration Guide

OL-13270-01

Chapter 46 Configuring Fallback Bridging

Configuring Fallback Bridging

Figure 46-1

Fallback Bridging Network Example

Fallback Bridging and Switch Stacks

When the stack master fails, a stack member becomes the new stack master by using the election process
described in

Chapter 5, “Managing Switch Stacks.”

The new stack master creates new VLAN-bridge

spanning-tree instance, which temporarily puts the spanning-tree ports used for fallback bridging into a
nonforwarding state. A momentary traffic disruption occurs until the spanning-tree states transition to
the forwarding state. All MAC addresses must be relearned in the bridge group.

Note

If a stack master running the IP services feature set fails and if the newly elected stack master is running
the IP base feature set, the switch stack loses its fallback bridging capability.

If stacks merge or if a switch is added to the stack, any new VLANs that are part of a bridge group and
become active are included in the VLAN-bridge STP.

When a stack member fails, the addresses learned from this member are deleted from the bridge group
MAC address table.

For more information about switch stacks, see

Chapter 5, “Managing Switch Stacks.”

Configuring Fallback Bridging

These sections contain this configuration information:

•

Default Fallback Bridging Configuration, page 46-3

•

Fallback Bridging Configuration Guidelines, page 46-4

•

Creating a Bridge Group, page 46-4

(required)