Reference Guide

spanning-tree mstp
Configures 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.
S5000
Syntax
spanning-tree mstp {edge-port [bpduguard [shutdown-on-
violation]] | loopguard | rootguard}
Parameters
edge-port Enter the keywords edge-port to configure 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.
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.
loopguard Enter the keyword loopguard to enable STP loop guard on
an MSTP port or port-channel interface.
rootguard Enter the keyword rootguard to enable root guard on an
MSTP port or port-channel interface.
Command
Modes
INTERFACE
Command
History
Version 9.0(1.3) Introduced on the S5000.
Usage
Information
On an MSTP switch, a port configured as an edge port immediately transitions to
the forwarding state. Only ports connected to end-hosts should be configured as
an edge port. Consider an edge port similar to a port with spanning-tree
portfast enabled.
If you do not enable shutdown-on-violation, BPDUs are still sent to the stack-
unit CPU.
Root guard and loop guard cannot be enabled at the same time on a port. For
example, if you configure loop guard on a port on which root guard is already
configured, 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 traffic from flowing through it.
For example, when Portfast BPDU guard and loop guard are both configured:
Multiple Spanning Tree Protocol (MSTP)
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