OS10 Enterprise Edition User Guide Release 10.4.0E(R3)

PDF

Root selection

MSTP determines the root bridge according to the lowest bridge ID. Assign a lower bridge priority to increase its likelihood of becoming the root bridge.

  • Assign a bridge priority number to a specific instance in CONFIGURATION mode (0 to 61440 in increments of 4096, default 32768). Use a lower priority number to increase the likelihood of the bridge to become a root bridge.
    spanning-tree mst 
                                           instance-number priority 
                                           priority
                                        

Assign root bridge priority

OS10(config)# spanning-tree mst 0
Verify root bridge priority
OS10# show spanning-tree active
                                 Spanning tree enabled protocol msti with force-version mst
                                 MSTI 0 VLANs mapped 1,31-4093
                                 Executing IEEE compatible Spanning Tree Protocol
                                 Root ID    Priority 32768, Address 3417.4455.667f
                                 Root Bridge hello time 2, max age 20, forward delay 15, max hops 20
                                 Bridge ID    Priority 32768, Address 90b1.1cf4.a523
                                 Configured hello time 2, max age 20, forward delay 15, max hops 20
                                 CIST regional root ID Priority 32768, Address 90b1.1cf4.a523
                                 CIST external path cost 500
                                 Interface                                           Designated
                                 Name           PortID   Prio  Cost  Sts  Cost Bridge ID     PortID
                                 ---------------------------------------------------------------------------
                                 ethernet1/1/5  128.276  128   500   FWD  0    32768   3417.4455.667f  128.146
                                 ethernet1/1/6  128.280  128   500   BLK  0    32768   3417.4455.667f  128.150
                                 Interface
                                 Name           Role PortID   Prio Cost Sts  Cost Link-type Edge
                                 --------------------------------------------------------------
                                 ethernet1/1/5  Root 128.276  128  500  FWD  0    AUTO      No
                                 ethernet1/1/6  Altr 128.280  128  500  BLK  0    AUTO      No
                              

Rate this content

Accurate
Useful
Easy to understand
Was this article helpful?
0/3000 characters
  Please provide ratings (1-5 stars).
  Please provide ratings (1-5 stars).
  Please provide ratings (1-5 stars).
  Please select whether the article was helpful or not.
  Comments cannot contain these special characters: <>()\