F5 Trunk port is connected to Cisco Switch Access Port

Frist:

The term "trunk" in the F5 world means something different than "trunk" in Cisco world.

In the F5 world (and most non-Cisco switches) a trunk is the same thing as Cicso Ethernet Channel. That is two or more physical interfaces that are treated logically as a single interface.

Second:

Does F52 have a connection to any other switches in your network? If so, then it is possible that you could have a loop.