NimbostratusWhy don't you simply create four different Virtual Servers, all using the same IP, but different ports? If you don't use SNAT on the VSs, then the client will see the original client IP (naturally, they must have a route back to the client, which traverses the BIG-IP -- unless you're using direct server return).
CumulonimbusAs Vernon mentions - Creating 4 VIPS (if your list of 4 ports is exhaustive) would be the far simplest implementation.
If you're stuck on the True-Client-IP variable, there's plenty of articles on Dev Central.
Just do a quick search
NimbostratusThe issue here is that the traffic is generated by Akamai IP, they also send True-Client-IP. The True-Client-IP is what I need to pass to the backend servers. I can just create 3 VS instead of just one, but wanted my config to be cleaner and less cluttered. Do you think it is still best to create 3?