It just doesn’t get much simpler than the physical bus topology when it comes to connecting nodes on a Local Area Network (LAN). The most common implementation of a linear bus topology is IEEE Ethernet. All devices in a bus topology are connected to a single cable called the bus, backbone, or ether. The transmission medium has a physical beginning and an end. All connections must be terminated with a resistor to keep data transmissions from being mistaken as network traffic. The terminating resistor must match the impedance of the cable.
It is not the purpose of this memo to take a position in the OSI vs. TCP/IP debate (although it is absolutely clear that TCP/IP offers the primary goals of OSI; namely, a universal, non-proprietary data communications protocol. In fact, TCP/IP does far more than was ever envisioned for OSI or for TCP/IP itself, for that matter). But before TCP/IP prevailed and OSI sort of dwindled into nothingness, many efforts were made to bring the two communities together. The ISO Development Environment (ISODE) was developed in 1990, for example, to provide an approach for OSI migration for the DoD. ISODE software allows OSI applications to operate over TCP/IP. During this same period, the Internet and OSI communities started to work together to bring about the best of both worlds as many TCP and IP features started to migrate into OSI protocols, particularly the OSI Transport Protocol class 4 (TP4) and the Connectionless Network Layer Protocol (CLNP), respectively. Finally, a report from the National Institute for Standards and Technology (NIST) in 1994 suggested that GOSIP should incorporate TCP/IP and drop the "OSI-only" requirement. [ NOTE: Some industry observers have pointed out that OSI represents the ultimate example of a sliding window ; OSI protocols have been "two years away" since about 1986.]