5K / 2K FEX issues
I like the general idea of using a Fex because it makes my life easier 99% of the time in having a central management point for all of my connectivity. Having our 5K’s VPC’d together and then VPC’ing down to our 2K’s makes life easy for the most part. For those not familiar with the process, this makes the 2K look like a line card on both 5K’s.
Unfortunately the challenge we have been facing recently is upgrading. Each FEX is dual homed between 2 5K’s. We upgraded one FEX successfully with no issue. We were going from an old code version 5 to a code train in version 7 which Cisco recommended. In order to properly upgrade the FEX’s we basically had to reload each Fex so they would take the new code version and then upgrade the secondary 5K. Had we upgraded the secondary 5K without doing this then all of the FEX’s would have rebooted at one time. This is a necessary evil in the process, but getting a window to do something like this can be a nightmare. You can have up to I think 24 FEX’s on your 5K’s which is a lot of switches that have to be accounted for at any given time when it comes to an upgrade.
I think I’m going to look to convert to a spine/leaf environment where we don’t have to worry about this going forward.