Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

the difference between system priority and bridge ID?

Hi,

I am reading the CCNP self Study BCMSN Official Exam Certificate Guide Fourth Edition. There is a System priority in the LACP set up. That is 2 bytes for priority value followed by a 6 byte MAC address. I am wondering what is the difference between system priority and the bridge ID related to STP. Bridge ID also consists of 2 bytes bridge priority and 6 bytes MAC address. if they are the same, why they are given two different names? Could any one give me a help on this?

thanks,

Cossak

1 REPLY
Cisco Employee

Re: the difference between system priority and bridge ID?

LACP system Priority is the combination of the LACP system priority value and the MAC address of the switch.

You can configure it using lacp system-priority priority_value

LACP uses the system priority with the switch MAC address to form the system ID and also during negotiation with other systems.

http://www.cisco.com/en/US/partner/docs/switches/lan/catalyst6500/ios/12.2SX/configuration/guide/channel.html#wp1033345

Each VLAN on each network device has a unique 64-bit bridge ID consisting of a bridge priority value, an extended system ID, and an STP MAC address allocation.

Configuring Bridge ID Priority

spanning-tree vlan vlan_id priority bridge_priority

http://www.cisco.com/en/US/partner/docs/switches/lan/catalyst6500/ios/12.2SX/configuration/guide/spantree.html#wp1096536

In short, both values are different.Both are used for different purpose.

Hope this helps.

492
Views
0
Helpful
1
Replies