Installation guide

Command Line Interface
4-80
4
Debug Commands
debug spanning-tree
This command configures debug settings for spanning tree processes. Use the no
form to disable debug mode for spanning tree.
Syntax
[no] debug spanning-tree [all | bpdu | events | root]
• all - Sets debugging for all options (config, bpdy, events, root).
• bpdu - Sets debugging for spanning-tree BPDUs.
• events - Sets debugging for spanning-tree topology changes.
• root - Sets spanning-tree root events.
Default Setting
Disabled
Command Mode
Privileged Exec
Command Usage
Use the bpdu option to display the content of BPDU packets whenever a
BPDU packet is transmitted or received, the event option to display TCN
messages whenever a topology change occurs, or the root option to display a
message whenever this switch becomes the spanning-tree root.
Example
Table 4-22 Debug Commands
Command Function Mode Page
debug spanning-tree Configures debug settings for spanning tree PE 4-80
Console#debug spanning-tree bpdu
02:08:23: STP/RSTP: rx BPDU from Ethernet 1/23. dropped
STP/RSTP: 01 80 C2 00 00 00 00 00 01 23 22 29 00 27 42 42 03
000002024E8000000001232222000000008000000001232222800700 00140002000F00
02:08:23: STP/RSTP: rx BPDU from Ethernet 1/23.
STP/RSTP: 01 80 C2 00 00 00 00 00 01 23 22 29 00 27 42 42 03
000002024E8000000001232222000000008000000001232222800700 00140002000F00
02:08:24 STP/RSTP tx BPDU from Ethernet 1/23
STP/RSTP: 01 80 C2 00 00 00 00 00 01 23 22 29 00 27 42 42 03
000002024E8000000001232222000000008000000001232222800700 00140002000F00
Console#debug spanning-tree events
02:15:29: STP/RSTP: sent Topology Change Notice on Ethernet 1/23
Console#debug spanning-tree root
02:14:00: STP/RSTP: recevied root 32768.0012CF3921C1 on Ethernet 1/23
02:14:00: MSTP: recevied root 32768.0.0030F1BD71C4 on Ethernet 1/23
02:16:39: STP/RSTP: This switch is the spanning tree root bridge
02:16:39: MSTP: This switch is the spanning tree root bridge at instance 1