Setting the Disputed BPDU Threshold

A disputed BPDU is one in which the flags field indicates a designated role and a learning state, and the priority vector is worse than that already held by the port. If a disputed BPDU is received, the port is forced to the listening state. Refer to the 802.1Q-2005 standard, IEEE Standard for Local and Metropolitan Area Networks – Virtual Bridged Local Area Networks, for a full description of the dispute mechanism, which prevents looping in cases of one-way communication.

The disputed BPDU threshold is an integer variable that represents the number of disputed BPDUs that must be received on a given port and SID before a disputed BPDU trap is sent and a syslog message is issued. For example, if the threshold is 10, a trap is issued when 10, 20, 30 (and so on) disputed BPDUs have been received. The trap indicates port, SID and total Disputed BPDU count.

Use this command to set the disputed BPDU threshold:

set spantree disputedbpduthreshold value

Default value is 0, which means that traps are not sent.