Cisco WS-C2960S-24PD-L Software Guide - Page 205

Chapter 7 Configuring the Switch Ports Configuring UniDirectional Link Detection Configuring UniDirectional Link Detection UniDirectional Link Detection (UDLD) is a Layer 2 protocol that detects and shuts down unidirectional links. You can configure UDLD on the entire switch or on an individual port. Use the udld reset command to reset all ports that have been shut down by UDLD. Beginning in privileged EXEC mode, follow these steps to configure UDLD on a switch: Step 1 Step 2 Command configure terminal udld enable Step 3 end Step 4 show running-config Purpose Enter global configuration mode. Enable UDLD on all switch ports. Use the udld interface configuration command to enable UDLD on a specific port. Return to privileged EXEC mode. Verify the entry by displaying the running configuration. Use the errdisable detect cause udld global configuration command to automatically place a port in error-disabled state, which is an operational state similar to link-down state, when a UDLD-related error condition is detected on the port. The errdisable recovery global configuration command automatically re-enables the port after a specified time, so that the port can try the operation again. The port would continue the error disable and recovery cycle until the UDLD error condition no longer exists. Note The errdisable commands are not available on the Catalyst 2900 LRE XL switches. Creating EtherChannel Port Groups Fast EtherChannel (FEC) and Gigabit EtherChannel port groups act as single, logical ports for high-bandwidth connections between switches or between switches and servers. Note You can create port groups of either Gigabit Ethernet ports or 100BASE-TX ports, but you cannot create a port group that has both port speeds. For the restrictions that apply to port groups, see the "Avoiding Configuration Conflicts" section on page 9-7. 78-6511-08 Catalyst 2900 Series XL and Catalyst 3500 Series XL Software Configuration Guide 7-7