Bridge priority

Mikdilly

Is it true that the Bridge priority is a combination of the default priority value of 32768 and the vlan number?

Ex: default value of 32768 + vlan 12 = BP of 32780??

aueddonline

I don't think so isn't it

prority and mac address and the mac is used as a tie breaker if the prorities match

Mikdilly

Cames across this on a website:

http://www.globalnettraining.com/pdfs/foundation.pdf

The following command reveals the base MAC address of the switch, the combination of
priority and the base MAC address is the BID for a given switch.
SW1#
Show spanning-tree bridge
Vlan Bridge ID HelloTime MaxAge FwdDly Protocol
VLAN0001 32769 (32768, 1) 0019.067f.8900 2 20 15 ieee
VLAN0012 32780 (32768, 12) 0019.067f.8900 2 20 15 ieee
VLAN0034 32802 (32768, 34) 0019.067f.8900 2 20 15 ieee
VLAN0056 32824 (32768, 56) 0019.067f.8900 2 20 15 ieee
VLAN0030 32898 (32768, 30) 0019.067f.8900 2 20 15 ieee

Note the priority starts with 32768, each VLAN that is created adds it’s VLAN number to
the default priority value (If the base priority and the VLAN number is added within the
parenthesis, the sum will be the priority for that given VLAN, which is displayed to the left
of the parenthesis), VLAN 12 adds 12 to the default priority value, therefore, the priority is
32780 and VLAN 34 adds 34 to the default priority value, therefore, the priority is 32802.
Note that the MAC is the base MAC address and it remains the same, in this case
(0019.067f.8900).

mikej412

Mikdilly wrote:

Is it true that the Bridge priority is a combination of the default priority value of 32768 and the vlan number?

Yes, but in the old days only when you got to the CCNP (or higher)

You may need to know it for the updated 640-802 exam.

# Describe enhanced switching technologies (including: VTP, RSTP, VLAN, PVSTP, 802.1q)