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For example, as shown previously, the switch/ router with UFD detects the uplink failure and automatically disables the
associated downstream link port to the server. To continue to transmit traffic upstream, the server with NIC teaming detects
the disabled link and automatically switches over to the backup link in order to continue to transmit traffic upstream.
Important Points to Remember
When you configure UFD, the following conditions apply.
● You can configure up to 16 uplink-state groups. By default, no uplink state groups are created in PMUX mode and uplink
state group 1 is created in Standalone and VLT modes.
○
An uplink-state group is considered to be operationally up if it has at least one upstream interface in the Link-Up state.
○ An uplink-state group is considered to be operationally down if it has no upstream interfaces in the Link-Up state. No
uplink-state tracking is performed when a group is disabled or in an Operationally Down state.
● You can assign physical port or port-channel interfaces to an uplink-state group in PMUX mode.
○ You can assign an interface to only one uplink-state group. Configure each interface assigned to an uplink-state group as
either an upstream or downstream interface, but not both.
○ You can assign individual member ports of a port channel to the group. An uplink-state group can contain either the
member ports of a port channel or the port channel itself, but not both.
○ If you assign a port channel as an upstream interface, the port channel interface enters a Link-Down state when the
number of port-channel member interfaces in a Link-Up state drops below the configured minimum number of
members parameter.
● If one of the upstream interfaces in an uplink-state group goes down, either a user-configurable set of downstream ports or
all the downstream ports in the group are put in an Operationally Down state with an UFD Disabled error. The order in which
downstream ports are disabled is from the lowest numbered port to the highest.
○ If one of the upstream interfaces in an uplink-state group that was down comes up, the set of UFD-disabled downstream
ports (which were previously disabled due to this upstream port going down) is brought up and the UFD Disabled error is
cleared.
● If you disable an uplink-state group, the downstream interfaces are not disabled regardless of the state of the upstream
interfaces.
○ If an uplink-state group has no upstream interfaces assigned, you cannot disable downstream interfaces when an
upstream link goes down.
● To enable the debug messages for events related to a specified uplink-state group or all groups, use the debug uplink-
state-group [group-id] command, where the group-id is from 1 to 16.
○ To turn off debugging event messages, use the no debug uplink-state-group [group-id] command.
○ For an example of debug log message, refer to .
Uplink Failure Detection (SMUX mode)
In Standalone or VLT modes, by default, all the server-facing ports are tracked by the operational status of the uplink LAG. If
the uplink LAG goes down, the aggregator loses its connectivity and is no longer operational. All the server-facing ports are
brought down after the specified defer-timer interval, which is 10 seconds by default. If you have configured VLAN, you can
reduce the defer time by changing the defer-timer value or remove it by using the no defer-timer command.
1. View the Uplink status group.
EXEC Privilege mode
show uplink-state-group
Dell#show uplink-state-group
Uplink State Group: 1 Status: Enabled, Down
2. Enable the uplink group tracking.
UPLINK-STATE-GROUP mode
enable
Dell(conf)#uplink-state-group 1
Dell(conf-uplink-state-group-1)#enable
Uplink Failure Detection (UFD)
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