Technical Reports

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UBC CS TR-85-04 Summary

LNTP --- An Efficient Transport Protocol for Local Area Networks, February 1985 Samuel T. Chanson, K. Ravindran and Stella Atkins

As interests in local area networks (LANs) grow so is the demand for protocols that run on them. It is convenient and a common practice to adopt existing transport protocols that had been designed for long haul networks (LHNs) for use in LANs. DARPA's Transmission Control Protocol/lnternet Protocol (TCP/IP) for example, is available in 4.2 BSD UNIX for interface to Ethernet and other LANs. This is not desirable from a performance standpoint as the control structure is usually much more complex than is necessary, and LANs and LHNs have very different characteristics. Though there exists simpler transport protocols such as the User Datagram Protocol (UDP) most do not provide adequate flow control which, because of the much higher channel speed, is critical in the LAN environment.

This paper discusses the unique characteristics and requirements of LANs and describes a new transport level protocol (LNTP) specifically designed for use on LANs. The fundamental philosophy in the design of LNTP is simplicity. Any features irrelevant to the LAN environment is not included. As well, LNTP uses a simple but effective deferred flow control mechanism which is activated only when the traffic intensity exceeds some value. This protocol has been implemented and runs under 4.2 BSD UNIX in place of TCP/IP. Detailed comparisons between LNTP, TCP and a few other protocols are given in the paper. Measurement data showed an improvement in network throughput rate of at least 30%, over that of TCP. The problem of internet communication is also addressed.


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