Administrator Guide

Designated port id is 128.384, designated path cost 2000
Number of transitions to forwarding state 1
BPDU (MRecords): sent 39291, received 7547
The port isnot in the Edge port mode, bpdu filter is disabled
Influencing MSTP Root Selection
MSTP determines the root bridge, but you can assign one bridge a lower priority to increase the probability
that it becomes the root bridge.
To change the bridge priority, use the following command.
• Assign a number as the bridge priority.
PROTOCOL MSTP mode
msti instance bridge-priority priority
A lower number increases the probability that the bridge becomes the root bridge.
The range is from 0 to 61440, in increments of 4096.
The default is 32768.
Example of Assigning and Verifying the Root Bridge Priority
By default, the simple configuration shown previously yields the same forwarding path for both MSTIs. The
following example shows how R3 is assigned bridge priority 0 for MSTI 2, which elects a different root bridge
than MSTI 2.
To view the bridge priority, use the show config command from PROTOCOL MSTP mode.
Dell(conf-mstp)#msti 2 bridge-priority 0
Dell(conf-mstp)#show config
!
protocol spanning-tree mstp
MSTI 2 bridge-priority 0
Dell(conf-mstp)#
Interoperate with Non-Dell Networking
OS Bridges
The Dell Networking OS supports only one MSTP region.
A region is a combination of three unique qualities:
• Name is a mnemonic string you assign to the region. The default region name is null.
• Revision is a 2-byte number. The default revision number is 0.
• VLAN-to-instance mapping is the placement of a VLAN in an MSTI.
Multiple Spanning Tree Protocol (MSTP) 608