Deployment Guide

spanning-tree mstp
Congures a Layer 2 MSTP interface as an edge port with (optionally) a bridge protocol data unit (BPDU) guard, or enables the root guard
or loop guard feature on the interface.
Syntax
spanning-tree mstp {edge-port [bpduguard [shutdown-on-violation]] | bpdufilter|
rootguard}
Parameters
edge-port Enter the keywords edge-port to congure the interface as a multiple spanning tree
edge port.
bpduguard (OPTIONAL) Enter the keyword portfast to enable Portfast to move the interface into
forwarding mode immediately after the root fails.
Enter the keyword bpduguard to disable the port when it receives a BPDU.
bpdulter (OPTIONAL) Enter the keyword edgeport to enable edge port conguration to move
the interface into forwarding mode immediately after the root fails. Enter the keyword
bpdufilter to stop sending and receiving BPDUs on the port-fast enabled ports.
shutdown-on-
violation
(OPTIONAL) Enter the keywords shutdown-on-violation to hardware disable an
interface when a BPDU is received and the port is disabled.
rootguard Enter the keyword rootguard to enable root guard on an MSTP port or port-channel
interface.
Command Modes INTERFACE
Supported Modes Full–Switch
Command History
Version Description
9.9(0.0) Introduced on the FN IOM.
8.3.16.1 Introduced on the MXL 10/40GbE Switch IO Module.
Usage Information
On an MSTP switch, a port congured as an edge port immediately transitions to the forwarding state. Only ports
connected to end-hosts should be congured as an edge port. Consider an edge port similar to a port with
spanning-tree portfast enabled.
Root guard and loop guard cannot be enabled at the same time on a port. For example, if you congure loop guard
on a port on which root guard is already congured, the following error message is displayed:
% Error:
RootGuard is configured. Cannot configure LoopGuard.
When used in an MSTP network, if root guard blocks a boundary port in the CIST, the port is also blocked in all
other MST instances.
Enabling Portfast BPDU guard and loop guard at the same time on a port results in a port that remains in a
blocking state and prevents trac from owing through it. For example, when Portfast BPDU guard and loop
guard are both congured:
• If a BPDU is received from a remote device, BPDU guard places the port in an err-disabled blocking state and
no trac 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 trac is forwarded on the port.
Multiple Spanning Tree Protocol (MSTP) 877