frame check error

I'm guessing your devices are connected 1G or greater, correct?

Make sure everything is set to Auto/Auto, long gone are the days where you need to hard set ports

Check all cables involved - Swap em until you no longer get the errors

If you're still getting errors swap SFPs

If that doesn't work try another switch port, they DO go bad once in a while

Not likely but possible bad port on the F5. Try another (might be hard to do without re-config though)

My money is on one of the first three..

And no, it's not normal and if you're getting a ton it can cause issues since you'll start getting a lot of retransmits..

Good luck!