Virtual Chassis FPC Replacement

(2015-04-16)

Problem

One of my FPC units in my virtual chassis is dead and I need to insert a replacement.

Solution

This assumes that you have a VC with sequentially numbered member-ids, meaning that the lowest-available member-id is the one you want the new FPC to have. If you want the new FPC to have a specific member-id other than the lowest-available one, you'll have to jump through some hoops (which are not documented here) to get what you want to happen to happen.

Unless you free up the member-ID of the FPC you've taken away, the new FPC will get a different member-ID and therefore not inherit the configuration you want it to inherit.

• Disconnect the dead FPC and obtain a replacement. Install firmware on the replacement that matches what is running on the survivors. Define a single vpc port, one of the ports you intend to use as a vpc port going forward.
• On the surviving master, issue the command

  request virtualchassis recycle member-id <#>

  … where <#> is FPC number of the unit you've just removed.
• Physically install the new FPC.
• Power up the new FPC and let it settle.
• Connect the one vpc port you configured on the new FPC to it's counterpart on the master. Let the VC settle. This took about a minute when I did it.
• You should now be able to connect up the rest of your vpc ports and network cables.

When I did this, I didn't lose any connectivity to, or through, the master while the VC settled, although there were some interesting user-generated issues caused by moving wires around incautiously.

Commentary

This process was a lot smoother than the disaster testing we did by pulling plugs and putting them back in. When we did that, the VC would usually refuse to pass any packets anywhere for up to 120 seconds while it decided who was a VC member and who the master was.