DELL S50V User Manual

Uplink Failure Detection (UFD) | 1085

 is supported on platform: 

s 

(S50 only)

Uplink Failure Detection (UFD) provides detection of the loss of upstream connectivity and, if used with 
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 since 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, in 

 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 configuration uses the connection to S1 as the primary path. Network traffic flows 
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 traffic, but the traffic 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 traffic upstream to R1.