CONTEXT [TCP/IP/Ethernet] Ethernet uses media access control identifiers (commonly referred to as MAC addresses) to distinguish between separate logical channels connecting two ports on the same physical transport network interface.
The Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP) of the Internet Protocol Suite use logical ports as communication endpoints, including client-side user ports (source of application requests) and server-side well-known ports for service access. (The Dictionary of Storage Networking Terminology)