Spanning-Tree Extend System-Id - Cisco 4500M Command Reference Manual

Chapter2 Cisco IOS Commands for the Catalyst 4500 Series Switches

spanning-tree extend system-id

To enable the extended system ID feature on a chassis that supports 1024 MAC addresses, use the
spanning-tree extend system-id command. To disable the feature, use the no form of this command.
Syntax Description
This command has no arguments or keywords.
Defaults
Enabled on systems that do not provide 1024 MAC addresses.
Command Modes
Global configuration
Command History Release
12.1(12c)EW
Usage Guidelines
Releases 12.1(13)E and later support chassis with 64 or 1024 MAC addresses. For chassis with 64 MAC
addresses, STP uses the extended system ID plus a MAC address to make the bridge ID unique for each
VLAN.
You cannot disable the extended system ID on chassis that support 64 MAC addresses.
Enabling or disabling the extended system ID updates the bridge IDs of all active STP instances, which
might change the spanning tree topology.
Examples
This example shows how to enable the extended system ID:
Switch(config)# spanning-tree extend system-id
Switch(config)#
Related Commands
show spanning-tree
78-16201-01
spanning-tree extend system-id
no spanning-tree extend system-id
Modification
Support for this command was introduced on the Catalyst 4500 series switch.
Catalyst4500 Series SwitchCiscoIOS Command Reference—Release 12.2(18)EW
spanning-tree extend system-id
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