Users Guide

Layer 2 Switching Commands 789
port. In this way, the root guard enforces the position of the root bridge. In
MSTP scenario the port may be designated in one of the instances while
being alternate in the CIST, and so on. Root guard is a per port (not a per port
per instance command) configuration so all the MSTP instances this port
participates in should not be in root role.
STP BPDU Filtering - STP BPDU filtering applies to all operational edge
ports. An Edge Port is supposed to be connected to hosts that typically do not
generate BPDUs. Ports on which BDPU filtering is enabled will drop both
transmitted and received BPDUs. As a result, loops may be formed on ports
for which BPDU filtering is enabled.
STP BPDU Flooding - STP BPDU flooding feature applies to an STP
disabled switch. To enable BPDU flooding on a port, STP must be disabled
on the switch administratively. When this feature is enabled on the switch, it
floods all the ports which have the BPDU flood feature enabled.
BPDU Storm Protection - If STP BPDUs are received at a rate of 15 pps or
greater for 3 consecutive seconds on a port, the port will be diagnostically
disabled. A message of the following form is logged:
<188> MAY 04 09:45:23 10.10.10.10-1 DOT1S[276072720]: dot1s_ih.c(1587)
15855515 %% Diagnostically disabling interface 2/0/41
Use the no shut command to return the port to service.
clear spanning-tree detected-protocols
Use the clear spanning-tree detected-protocols command to restart the
protocol migration process (force the renegotiation with neighboring
switches) on all interfaces or on the specified interface.
Syntax
clear spanning-tree detected-protocols [ interface-id ]
• interface-id—An Ethernet or port channel interface identifier
Default Configuration
This command has no default setting.
Command Mode
Privileged Exec mode