Cisco Nexus 5000 Series Command Reference Release 4.0(1a)N2(1) (OL-16599-01, March 2009)

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Cisco Nexus 5000 Series Command Reference
OL-16599-01
Chapter 2 Ethernet Commands
clear spanning-tree detected-protocol
clear spanning-tree detected-protocol
To restart the protocol migration, use the clear spanning-tree detected-protocol command. With no
arguments, the command is applied to every port of the switch.
clear spanning-tree detected-protocol [interface {ethernet interface | port-channel channel}]
Syntax Description
Command Default None
Command Modes EXEC mode
Command History
Usage Guidelines Rapid per VLAN Spanning Tree Plus (Rapid PVST+) and Multiple Spanning Tree (MST) have built-in
compatibility mechanisms that allow them to interact properly with other versions of IEEE spanning tree
or other regions. For example, a switch running Rapid PVST+ can send 802.1D bridge protocol data
units (BPDUs) on one of its ports when it is connected to a legacy device. An MST switch can detect
that a port is at the boundary of a region when it receives a legacy BPDU or an MST BPDU that is
associated with a different region.
These mechanisms are not always able to revert to the most efficient mode. For example, a Rapid PVST+
switch that is designated for a legacy 802.1D bridge stays in 802.1D mode even after the legacy bridge
has been removed from the link. Similarly, an MST port assumes that it is a boundary port when the
bridges to which it is connected have joined the same region.
To force a port to renegotiate with its neighbors, enter the clear spanning-tree detected-protocol
command.
Examples This example shows how to restart the protocol migration on a specific interface:
switch# clear spanning-tree detected-protocol interface ethernet 1/4
Related Commands
interface (Optional) Specifies the interface type.
ethernet interface Slot and port number.
port-channel channel EtherChannel number.
Release Modification
4.0(0)N1(1a) This command was introduced.
Command Description
show spanning-tree Displays information about the spanning tree state.