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Chapter 34  MSTP Commands 
MSTP (Multiple Spanning Tree Protocol), compatible with both STP and RSTP and subject to 
IEEE 802.1s, can disbranch a ring network. STP is to block redundant links and backup links as 
well as optimize paths. 
34.1 debug spanning-tree 
Description 
The  debug spanning-tree  command is used to enable  debuggning of 
spanning-tree activities. To disable the debugging  function, please use no 
debug spanning-tree command. 
Syntax 
debug spanning-tree { all | bpdu receive | bpdu transmit | cmpmsg | errors | 
flush | init | migration | proposals | roles | state | tc } 
no debug spanning-tree { all | bpdu receive | bpdu transmit | cmpmsg | errors | 
flush | init | migration | proposals | roles | state | tc } 
Parameters 
all —— Display all the spanning-tree debug messages. 
bpdu receive —— Display the debug messages of the received spanning-tree 
bridge protocol data unit (BPDU). 
bpdu transmit  ——  Display the debug messages of the sent spanning-tree 
BPDU. 
cmpmsg —— Display the message priority debug messages. 
errors —— Display the MSTP error debug messages. 
flush —— Display the address table flushing debug messages. 
init —— Display the data structure initialization debug messages. 
migration —— Display the version migration debug messages. 
proposals —— Display the MSTP handshake debug messages. 
roles —— Display the MSTP interface role switchling debug messages. 
state —— Display the MSTP interface state change debug messages. 
tc —— Display the MSTP topology event debug messages. 
Command Mode 
Privileged EXEC Mode