Cisco Catalyst 2950 Command Reference

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Catalyst 2950 and Catalyst 2955 Switch Command Reference
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Chapter 2 Catalyst 2950 and 2955 Cisco IOS Commands
udld
udld
Use the udld global configuration command to enable aggressive or normal mode in the UniDirectional
Link Detection (UDLD) and to set the configurable message timer. Use the no form of this command to
return to the default settings.
udld {aggressive | enable | message time message-timer-interval}
no udld {aggressive | enable | message time}
Syntax Description
Defaults UDLD is disabled on all fiber-optic interfaces.
The message timer is set at 60 seconds.
Command Modes Global configuration
Command History
Usage Guidelines Use the udld global configuration command to enable UDLD only on fiber-optic ports. To enable UDLD
on other interface types, use the udld interface configuration command.
UDLD supports two modes of operation: normal mode (the default) and aggressive mode. In normal
mode, UDLD detects unidirectional links due to misconnected interfaces on fiber-optic connections. In
aggressive mode, UDLD also detects unidirectional links due to one-way traffic on fiber-optic and
twisted-pair links and due to misconnected interfaces on fiber-optic links. For information about normal
and aggressive modes, see the “Understanding UDLD” section in the software configuration guide for
this release.
If you change the message time between probe packets, you are making a trade-off between the detection
speed and the CPU load. By decreasing the time, you can make the detection-response faster but increase
the load on the CPU.
You can use these commands to reset an interface shut down by UDLD:
• The udld reset privileged EXEC command to reset all interfaces shut down by UDLD
• The shutdown and no shutdown interface configuration commands
aggressive Enable UDLD in aggressive mode on all fiber-optic interfaces.
enable Enable UDLD in normal mode on all fiber-optic interfaces.
message time
message-timer-interval
Configure the period of time between UDLD probe messages on ports that
are in the advertisement phase and are determined to be bidirectional. The
range is 7 to 90 seconds.
Release Modification
12.0(5.2)WC(1) This command was introduced.
12.1(6)EA2 The udld enable global configuration command was changed to udld
(global configuration).

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