I need to mirror certain types of traffic in and out of a serial port on a 3845 router. The router has a 16 port switch card in it which has a trunk port to C6500s, 3850s, etc. It also of course has a gigE port that is a standard L3 interface to the rest of the environment as well. In addition to ingress and egress traffic on the gigE port, there are multiple serial interfaces on the router in addition to a couple of Ethernet interfaces that could all potentially talk to the serial port in question.
Is there some way besides some tricky things with policy based routing/redirection/hubs/switches/etc to get the features of SPAN/RSPAN/etc to make this happen? While that would work, it certainly complicates the things and could potentially make communications to and from the serial port dependent on yet another piece of hardware.