Cisco Systems OL-8241-02 Manual De Usuario

To set the bridge maximum age to 21, enter:

(config)# bridge max-age 21

To restore the default maximum age of 6, enter:

(config)# no bridge max-age

In spanning tree, the 2-octet field is prepended to the 6-octet MAC address to form 
an 8-octet bridge identifier. The device with the lowest bridge identifier is 
considered the highest priority bridge and becomes the root bridge. By default, the 
bridge priority is set to 32768. Use the bridge priority command to set the 
priority that the bridge spanning tree uses to choose the root bridge in the network. 
The range for bridge priority is 0 to 65535. 

For example:

(config)# bridge priority 1700

To restore the bridge priority to the default of 32768, enter:

(config)# no bridge priority

Spanning-tree bridging is enabled by default. When you disable spanning-tree 
bridging, the CSS drops those bridge protocol data units (BPDUs) that it 
recognizes as BPDUs, but forwards the Cisco Systems 802.1Q BPDUs (tagged 
with the proprietary 01-00-0c-cc-cc-cc-cd destination MAC address) on an 
802.1Q VLAN trunk. The CSS can still operate in an 802.1Q spanning-tree 
environment as long as you do not require that the CSS put any of its ports into a 
blocking state. 

Disabling spanning-tree bridging may make your network susceptible to packet 
storms.