VICTORIA UNIVERSITY OF WELLINGTON

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Recoverable Sequence Transmission

Protocols

Ewan D. Tempero and Richard E. Ladner

Technical Report CS-TR-93/4
September 1993

Abstract

We consider the sequence transmission problem, that is, the problem of transmitting an infinite sequence of messages x1x2x3 : : : over a channel which can both lose and reorder packets. We define performance measures, ideal transmission cost and recovery cost, for protocols which solve the sequence transmission problem. Ideal transmission cost measures the number of packets needed to deliver xn when the channel is behaving ideally and recovery cost measures how long it takes, in terms of number of messages delivered, for the ideal transmission cost to take hold once the channel begins behaving ideally. We also define lookahead which measures the number of messages the sender can be ahead of the receiver in the protocol. We show that any protocol with constant recovery cost and lookahead requires linear ideal transmission cost. We describe a protocol Plin which has ideal transmission cost 2n, recovery cost 1, and lookahead 0.

Publishing Information

This work was supported by NSF Grants CCR-8714782 and CCR-9108314. It has been submitted for publication. A preliminary version of this paper appeared in the Proceedings of the Ninth Annual ACM Symposium on Principles of Distributed Computing, August 22-24, 1990 [TL90].