Cisco Catalyst 2950 Command Reference

2-53
Catalyst 2950 and Catalyst 2955 Switch Command Reference
OL-10102-01
Chapter 2 Catalyst 2950 and 2955 Cisco IOS Commands
clear spanning-tree detected-protocols
clear spanning-tree detected-protocols
Use the clear spanning-tree detected-protocols privileged EXEC command to restart the protocol
migration process (force the renegotiation with neighboring switches) on all interfaces or on the
specified interface.
clear spanning-tree detected-protocols [interface interface-id]
Syntax Description
Command Modes Privileged EXEC
Command History
Usage Guidelines A switch running the rapid per-VLAN spanning-tree plus (rapid-PVST+) protocol or the Multiple
Spanning Tree Protocol (MSTP) supports a built-in protocol migration mechanism that enables it to
interoperate with legacy IEEE 802.1D switches. If a rapid-PVST+ switch or an MSTP switch receives a
legacy IEEE 802.1D configuration bridge protocol data unit (BPDU) with the protocol version set to 0,
it sends only IEEE 802.1D BPDUs on that port. A multiple spanning-tree (MST) switch can also detect
that a port is at the boundary of a region when it receives a legacy BPDU, an MST BPDU (version 3)
associated with a different region, or an RST BPDU (version 2).
However, the switch does not automatically revert to the rapid-PVST+ or the MSTP mode if it no longer
receives IEEE 802.1D BPDUs because it cannot determine whether the legacy switch has been removed
from the link unless the legacy switch is the designated switch. Use the clear spanning-tree
detected-protocols command in this situation.
Examples This example shows how to restart the protocol migration process on an interface:
Switch# clear spanning-tree detected-protocols interface fastethernet0/1
interface interface-id (Optional) Restart the protocol migration process on the specified interface.
Valid interfaces include physical ports, VLANs, and port channels. The
VLAN range is 1 to 4094. The port-channel range is 1 to 6.
Release Modification
12.1(9)EA1 This command was introduced.
12.1(20)EA2 This command was added to the SI.

Cisco Catalyst 2950 Specifications

General

Forwarding Bandwidth	8.8 Gbps
Switching Capacity	13.6 Gbps
Forwarding Rate	6.6 Mpps
Weight	3.6 kg
RAM	16 MB
Flash Memory	8 MB
Operating Humidity	10% to 85% non-condensing
Uplink Ports	2 x 10/100/1000Base-T
Dimensions	4.4 cm x 44.5 cm x 24.2 cm
Remote Management Protocol	SNMP, Telnet, HTTP
Features	Quality of Service (QoS), VLAN support
Compliant Standards	IEEE 802.3, IEEE 802.3u, IEEE 802.1D, IEEE 802.1Q, IEEE 802.1p
Status Indicators	system
Operating Temperature	0 to 45°C
Ports	24 x 10/100 Ethernet ports
MAC Address Table Size	8, 192 entries
Power Supply	Internal 100-240V AC, 50-60Hz