Enabling The Extended System Id - Cisco 7604 Configuration Manual

Configuring STP

Enabling the Extended System ID

The extended system ID is enabled permanently on chassis that support 64 MAC addresses.
Note
You can enable the extended system ID on chassis that support 1024 MAC addresses (see the
"Understanding the Bridge ID" section on page
To enable the extended system ID, perform this task:
Command
Step 1
Router(config)# spanning-tree extend system-id
Router(config)# no spanning-tree extend system-id
Step 2
Router(config)# end
Step 3
Router# show spanning-tree vlan vlan_ID
Note When you enable or disable the extended system ID, the bridge IDs of all active STP instances are
updated, which might change the spanning tree topology.
This example shows how to enable the extended system ID:
Router# configure terminal
Router(config)# spanning-tree extend system-id
Router(config)# end
Router#
This example shows how to verify the configuration:
Router# show spanning-tree summary | include Extended
Extended system ID is enabled.
Configuring the Root Bridge
Cisco 7600 series routers maintain a separate instance of STP for each active VLAN. A bridge ID,
consisting of the bridge priority and the bridge MAC address, is associated with each instance. For each
VLAN, the network device with the highest-priority (lowest-numerical) bridge ID becomes the root
bridge for that VLAN.
To configure a VLAN instance to become the root bridge, enter the spanning-tree vlan vlan_ID root
command to modify the bridge priority from the default value (32768) to a significantly lower value.
Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
20-24
Chapter 20 Configuring STP and Prestandard IEEE 802.1s MST
20-2).
Purpose
Enables the extended system ID.
Disables the extended system ID.
Note You cannot disable the extended system ID on
chassis that support 64 MAC addresses or when
you have configured extended range VLANs (see
"STP Default Configuration" section on
page 20-21).
Exits configuration mode.
Verifies the configuration.
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