Cisco Nexus 5500 Series - Page 31

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Cisco Nexus 5500 Series NX-OS Layer 2 Interfaces Command Reference
OL-27880-02
Chapter C 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 slot/[QSFP-module/]port |
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
interface (Optional) Specifies the interface type.
ethernet slot/[QSFP-module/]port Specifies the Ethernet interface and the slot number and port
number. The slot number is from 1 to 255. The QSFP-module
number is from 1 to 4. The port number is from 1 to 128.
Note The QSFP-module number applies only to the QSFP+
Generic Expansion Module (GEM).
port-channel channel Specifies the EtherChannel number. The number range is from 1
to 4096.
Release Modification
6.0(2)N1(1) Support for the QSFP+ GEM was added.
5.2(1)N1(1) This command was introduced.