FEX bootup behavior

[Doctor9]

Hello Everyone,

My question: Does a FEX have to pull its software from the Nexus switch each time it (the FEX) reboots?

Background:

We have 2 x NX5672UP which share connectivity to 14 x FEX (N2K-C2348TQ-10GE & N2K-C2348UPQ-10GE).

We have to move equipment around in our data center and I am trying come up with an of estimate how long it will take get the pair of Nexus' and the 14 FEX' up and running again. If a FEX is able to boot up on its own and then just waits for connectivity to its Nexus switch then we would probably be able to do it within a shorter time frame.

Many thanks!

[Doctor9 · Accepted solution]

I managed to build a lab and verify things for myself:
The FEX only needs to download an image from the Nexus when it is not on the same code as the Nexus.
Afterwards, when the FEX has the same code it is able to boot on itself and just waits to be connected to a Nexus switch.
It takes the FEX around 4 minutes to boot up - if you connect the FEX to the Nexus afterwards it takes less than 20 seconds for the FEX to come online / attached and operational.

[tcmckay]

This is my experience as well. FEX only take longer when the nx-os on the switch is different than on the FEX. It will then pull the correct image from the parent switch and then reload. If the FEX and parent switch are on the same software release it will take less time to reload.

[shulipal]

Hello Team,

Just wanted to add few things to it, when the FEX's are connected in vPC enviroments, you need to perform the code upgrade from the vPC primary[opertaional primary] so that New image will be downloaded to FEX.

But if you see the "show fex" output you will see version-missmatch in the secondary vPC switch, If you start performing the code upgrade on vPC secondary FEX will go for reload and will be back online in 5-10 min.

Hosts will loose the connectivity still the FEX comes online.

Thanks,

Shivakumar Hulipalled