Cisco Catalyst 4500 Series Configuration Manual page 1085

Chapter 2
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.
Command Default Enabled on systems that do not provide 1024 MAC addresses.
Command Modes Global configuration mode
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
The following example shows how to enable the extended system ID:
Switch(config)# spanning-tree extend system-id
Switch(config)#
Related Commands Command
show spanning-tree
spanning-tree extend system-id
no spanning-tree extend system-id
Modification
This command was introduced on the Catalyst 4500 series switch.
Catalyst 4500 Series Switch Cisco IOS Command Reference—Release XE 3.9.xE and 15.2(5)Ex
Description
Displays spanning-tree information.
spanning-tree extend system-id
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