What is Uplinkfast in Spanning Tree Protocol?

The STP protocol was developed to prevent loops in the OSI model layer 2. In a cable failure that occurs in a redundant network, several features have been developed due to the high STP Convergence time.

What is Uplinkfast in Spanning Tree Protocol?

Understanding the Uplinkfast Feature

It is an indispensable situation for today’s network networks to have redundant routes. The server farm section of a corporate network must always be active. Because the servers here should serve the institution’s customers without interruption. In addition, the UplinkFast feature is exclusive to Cisco.

Therefore, in such network environments, the network backup process is very important. Although it causes a loop in the 2nd layer devices in the network backup process, the STP protocol has been developed. For example; more than one network cable is connected to one Switch, and when one of these cables fails, the other must be activated. This is where STP comes into play.

When one of the cables connected to the switch fails, it may take some time for the other cable to be activated. This cable, which is in blocking mode, can be active for up to 50 seconds. One way to shorten this time is to configure the UplinkFast configuration on the Switch.

If you remember, we have stated that in order to increase STP performance, we need to configure the interfaces of devices such as computers and servers connected to Switch as PortFast.

How does it work?

In the event of a cable malfunction, the STP protocol provides a fast convergence/integration while updating the network map. It has also been developed to work on a Switch that has Blocking Mode on a redundant network.

In addition, the switch will go into Forwarding mode without processing Listening and Learning port states.

In addition, Cisco recommends that this feature be implemented only on the network’s access layer. As a result, one Switch will be active faster than one backup link when one link fails.

Additionally, if you enable this feature, the Switch must-have Blocking mode. This is because the redundant link is quickly active.

In the image below, the Switch to be configured as UplinkFast is specified.

Reviewing Port Status of Cisco Switch

As a result, this feature will put the GigabitEthernet0/2 interface in Forwarding mode in 15-20 seconds when Switch1’s network cable fails.

How to Enable it?

To enable UplinkFast on the Switch, perform the following command in Switch global config mode.

Switch# conf t
Switch(config)# spanning-tree uplinkfast

   Video

You can watch the video below for the UplinkFast configuration and also subscribe to our YouTube channel to support us!

   Final Word


With the UplinkFast feature, we can slightly increase the performance of the Spanning Tree protocol on our network. It is a good option to enable it in the standard STP configuration. And in addition, it is recommended to enable the STP BackboneFast feature. Thanks for following us!

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