create pool that forwards entire subnet

I answered my own question with some trial & error, it is the IP forwarding virtual server that is needed but in v. 9.x, you don't assign a pool to it, you only list the subnet and mask for the destination. Apparently the F5 takes any packets destined for that subnet and uses this VS to alert it that there will be no need to send such packets to a pool, but rather just send it on to the dest. IP in the packet. I guess this is ostensibly for intercommunication between devices on the same side of the F5 rather than for the normal traffic that goes thru the F5.