Administrator Guide

• If a BPDU is received from a remote device, BPDU guard places the port in an Err-Disabled Blocking state and
no traffic is forwarded on the port.
• If no BPDU is received from a remote device, loop guard places the port in a Loop-Inconsistent Blocking state
and no traffic is forwarded on the port.
To display the type of STP guard (Portfast BPDU, root, or loop guard) enabled on a port, enter the show
spanning-tree 0 command.
On PE ports and on VP-LAGs (lags formed with PE ports):
• spanning-tree with bpdu guard shutdown-on-violation is enabled by default.
• no spanning tree command is valid
Hence, you cannot issue the spanning-tree stp-id command on the PE ports (peGigE ports) and issuing
this command on VP-LAG ports results in a failure.
1606 Spanning Tree Protocol (STP)