In one embodiment, a router establishes a serial-over-TCP/IP (Transmission Control Protocol/Internet Protocol) communication session between terminal units using raw-TCP encapsulation. For the session, the router maps serial characters to TCP out-of-band (OOB) communication fields, maps serial flow control signals to TCP/IP receiver-window advertisements, and dynamically adjusts a TCP/IP priority based on serial payload priority. Accordingly, the router may thus communicate data over the serial-over-TCP/IP session based on the mappings and priority.