Reliable message transport for network communication

Shawn David Ostermann, Purdue University

Abstract

Computer communication software presents the abstraction of a single, global communication system, known as an internetwork, over which any connected computer can send information to any other connected computer. The information transfer service provided by an internetwork, however, is not guaranteed to be reliable; information can be lost, delayed, duplicated, or corrupted. A piece of communication software known as a transport protocol is responsible for providing a layer of reliability above the internetwork layer. A transport protocol provides the abstraction of a reliable mechanism for the exchange of information between applications. An exchange of information between applications, or conversation, consists of units of data called messages. For applications that rely on relatively short-lived conversations, existing widely-used transport protocols impose a high efficiency penalty because of the amount of time required by the transport protocol to establish, manage, and terminate short-lived conversations. This dissertation defines a conceptual model of a transport protocol and the underlying internetwork, and characterizes the various aspects of protocol reliability as being Arrival, Order, Uniqueness, Integrity, Replay, and Performance. Using these models of the transport protocol, the internetwork, and the various aspects of reliability, this dissertation describes the Simple Reliable Message Protocol, SRMP, a new message transport protocol. SRMP uses novel reliability mechanisms that allow it to efficiently manage short-lived conversations. SRMP's performance is compared to the performance of existing transport protocols in the areas of short-lived conversation efficiency, the amount of protocol acknowledgement information required, and performance in the presence of congestion. Experiments comparing SRMP to existing transport protocols show that SRMP manages short-lived conversations more efficiently than existing, widely-used transport protocols. Additional experiments indicate that decreasing the amount of acknowledgement information returned by SRMP, by extending the acknowledgement interval, can further improve the protocol's performance in certain cases. Further experimental data shows that SRMP's congestion control mechanisms are equivalent to the mechanisms used by the commonly used transport protocol TCP, whose congestion control mechanisms have been widely studied.

Degree

Ph.D.

Advisors

Comer, Purdue University.

Subject Area

Computer science

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