Dynamic planning based protocols for real-time communication in LAN and switched LAN environments

The problem of real-time communication over a multiple access network has b een well studied in the recent past. However, there are very few protocols that can bound the worst case channel access time to ensure predictability of message transmission for the LAN environment. In addition, there has bee n no prior work addressing real-time communication over a switched (extende d) local area network (SLAN), where several LAN segments are connected thro ugh a switch. In this paper, we propose real-time protocols for the LAN and the SLAN. The proposed protocols are based on CSMA/CD with deterministic c ollision resolution and belong to the dynamic planning based category, wher e an admission test is performed for guaranteeing message transmission. The admission test used in the proposed protocols is based on the worst case c hannel access time that can elapse before a particular node can start trans mitting its message. We also compute the worst case buffer requirement at t he switch for the proposed SLAN protocols. We study the effectiveness of th e proposed protocols through extensive simulation studies. (C) 2001 Elsevie r Science B.V. All rights reserved.