Deployment Guide

Uplink Failure Detection (UFD)

Supported Modes

Standalone, PMUX, VLT, Stacking

Topics:

• Feature Description

• How Uplink Failure Detection Works

• UFD and NIC Teaming

• Important Points to Remember

• Uplink Failure Detection (SMUX mode)

• Conguring Uplink Failure Detection (PMUX mode)

• Clearing a UFD-Disabled Interface (in PMUX mode)

• Displaying Uplink Failure Detection

• Sample Conguration: Uplink Failure Detection

Feature Description

UFD provides detection of the loss of upstream connectivity and, if used with network interface controller (NIC) teaming, automatic

recovery from a failed link.

A switch provides upstream connectivity for devices, such as servers. If a switch loses its upstream connectivity, downstream devices also

lose their connectivity. However, the devices do not receive a direct indication that upstream connectivity is lost because connectivity to

the switch is still operational

UFD allows a switch to associate downstream interfaces with upstream interfaces. When upstream connectivity fails, the switch disables

the downstream links. Failures on the downstream links allow downstream devices to recognize the loss of upstream connectivity.

For example, as shown in the following illustration, Switches S1 and S2 both have upstream connectivity to Router R1 and downstream

connectivity to the server. UFD operation is shown in Steps A through C:

• In Step A, the server conguration uses the connection to S1 as the primary path. Network trac ows from the server to S1 and then

upstream to R1.

• In Step B, the upstream link between S1 and R1 fails. The server continues to use the link to S1 for its network trac, but the trac is

not successfully switched through S1 because the upstream link is down.

• In Step C, UFD on S1 disables the link to the server. The server then stops using the link to S1 and switches to using its link to S2 to

send trac upstream to R1.

NOTE

: In Standalone and VLT modes, the UFD group number is 1 by default and cannot be changed.

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