Port multiplexing apparatus and methods are disclosed. Time slots in a time division multiplexing (TDM) scheme are allocated to transfer signals such as Ethernet or Fiber Channel packets associated with ports of a signal processing device. Signals associated with multiple ports are transferred between those ports and another signal processing device over a single logical link in accordance with the time slot allocation. An indication of the time slot allocation may also be transferred on the link, illustratively by replacing protocol overhead traffic to be transmitted on the link with allocation information. At a receiver, the replaced protocol overhead traffic may be substituted back into a received multiplexed signal. A port multiplexing apparatus may be controllable to operate in a multiplexing mode or in a non-multiplexing mode. Aspects of the invention may also be embodied in other forms, such as in a data structure stored on a machine-readable medium.