Connectivity Guide

Table Of Contents
Uplink Failure Detection
Uplink failure detection (UFD) indicates the loss of upstream connectivity to servers connected to the switch.
A switch provides upstream connectivity for devices, such as servers. If the switch loses upstream connectivity, the downstream devices
also lose connectivity. However, the downstream devices do not generally receive an indication that the upstream connectivity was lost
because connectivity to the switch is still operational. To solve this issue, use UFD.
UFD associates downstream interfaces with upstream interfaces. When upstream connectivity fails, the switch operationally disables its
downstream links. Failures on the downstream links allow downstream devices to recognize the loss of upstream connectivity. This allows
the downstream servers to select alternate paths, if available, to send trac to upstream devices.
UFD creates an association between upstream and downstream interfaces known as uplink-state group. An interface in an uplink-state
group can be a physical Ethernet or bre channel interface or a port-channel.
An enabled uplink-state group tracks the state of all assigned upstream interfaces. The failure of upstream interfaces results in automatic
disabling of downstream interfaces in the uplink-state group, as shown in the following illustration. If only one of the upstream interfaces in
an uplink-state group goes down, a specic number of downstream interfaces in the same uplink-state group go down. You can congure
the number of downstream interfaces that go down based on the trac conditions from the server to the upstream interfaces. This avoids
overloading trac on upstream ports.
By default, if all the upstream interfaces in an uplink-state group go down, all the downstream interfaces in the same uplink-state group are
set into a link-down state.
In addition, in an uplink-state group, you can congure automatic recovery of downstream ports when there is a change in the link status of
uplink interfaces.
You can also bring up downstream interfaces that are in an UFD-disabled error state manually.
UFD Topology
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858 Uplink Failure Detection