Local synchronous capacity allocation schemes for guaranteeing message deadlines with the timed token protocol

Abstract

We study the problem of guaranteeing synchronous message deadlines in communication networks where the timed token medium access control protocol is em- ployed. Synchronous capacity, defined as ihe max- rmum time for which a node can transmit its syn- chronous messages every time it receives the token, is a key parameter in the control of synchronous message transmission. To ensure the iransmission of synchronous messages before their deadlines, syn- chronous capacities must be properly allocated to indi- vidual nodes. In this paper, we develop and analyze a class oflo- col synchronous capacity allocation schemes. A local scheme allocates the synchronous capacity 20 a node without using information about messages on the other nodes while a global allocation scheme uses network wide information in ihe allocaiion process. Use of local schemes benefits ihe run-time mana emeni of network in the sense that the entire networi can continue its normal operation while individual nodes chan e iheir synchronous capacities in response io the cianging message parameters. We evaluaie the local allocation schemes proposed in terms of their ability to guaran- tee message deadlines. We show that one of the local allocation schemes proposed can achieve the same per- formance as that of the best global allocation scheme known to date.