Users Guide

EXEC Privilege mode
debug spanning-tree mstp bpdu
• Display MSTP-triggered topology change messages.
debug spanning-tree mstp events
Examples of Viewing MSTP Configurations
To ensure all the necessary parameters match (region name, region version, and VLAN to instance mapping),
examine your individual routers.
To show various portions of the MSTP configuration, use the show spanning-tree mst commands.
To view the overall MSTP configuration on the router, use the show running-configuration spanning-
tree mstp in EXEC Privilege mode.
To monitor and verify that the MSTP configuration is connected and communicating as desired, use the
debug spanning-tree mstp bpdu command.
Key items to look for in the debug report include:
• MSTP flags indicate communication received from the same region.
• As shown in the following, the MSTP routers are located in the same region.
• Does the debug log indicate that packets are coming from a “Different Region”? If so, one of the
key parameters is not matching.
• MSTP Region Name and Revision.
• The configured name and revisions must be identical among all the routers.
• Is the Region name blank? That may mean that a name was configured on one router and but was
not configured or was configured differently on another router (spelling and capitalization counts).
• MSTP Instances.
• To verify the VLAN to MSTP instance mapping, use the show commands.
• Are there “extra” MSTP instances in the Sending or Received logs? This may mean that an
additional MSTP instance was configured on one router but not the others.
The following example shows the show run spanning-tree mstp command.
Dell#show run spanning-tree mstp
!
protocol spanning-tree mstp
name Tahiti
revision 123
MSTI 1 VLAN 100
MSTI 2 VLAN 200,300
The following example shows viewing the debug log of a successful MSTP configuration.
Dell#debug spanning-tree mstp bpdu
MSTP debug bpdu is ON
Dell#
4w0d4h : MSTP: Sending BPDU on Te 2/21/1 :
ProtId: 0, Ver: 3, Bpdu Type: MSTP, Flags 0x6e
CIST Root Bridge Id: 32768:0001.e806.953e, Ext Path Cost: 0
Regional Bridge Id: 32768:0001.e806.953e, CIST Port Id: 128:470
Msg Age: 0, Max Age: 20, Hello: 2, Fwd Delay: 15, Ver1 Len: 0, Ver3 Len: 96
Name: Tahiti, Rev: 123, Int Root Path Cost: 0
Rem Hops: 20, Bridge Id: 32768:0001.e806.953e
4w0d4h : INST 1: Flags: 0x6e, Reg Root: 32768:0001.e806.953e, Int Root Cost: 0
Multiple Spanning Tree Protocol (MSTP) 643