Reference Guide

234 | Uplink Failure Detection (UFD)
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Important Points to Remember
UFD operates as follows on an Aggregator:
• Uplink-state group 1 is created by default with the uplink LAG 128 as the upstream interface and all
server ports as downstream interfaces.
When the uplink LAG goes down, all server interfaces are brought down and placed in UFD error-dis-
abled state.
When the uplink LAG comes up again, server interfaces are brought up (Oper UP) and the error-dis-
abled state is cleared.
• You can configure a defer timer in the uplink-state group. The defer timer prevents unwanted flapping
of server ports when the uplink LAG flaps.
The defer timer is also helpful in scenarios similar to this one:
The uplink LAG consists of ports connected to two ToR switches. The currently active LAG goes
down. Without the defer timer, server-facing ports would be shut down before even trying to bring up
the LAG with the second ToR switch.
• To enable the debug messages for events related to a specified uplink-state group or all groups, enter
the
debug uplink-state-group [group-id] command, where group-id is 1 to 16.
To turn off debugging event messages, enter the
no debug uplink-state-group [group-id] command.