New protocols for hard real-time communication in the switched LAN environment

The problem of real-time communication over a multiple access network has been well studied in the past. But, there has been no prior work addressing real-time communication over a switched local area network (SLAN), where several LAN segments are connected through a switch. In this paper we propose real-time protocols for the SLAN. The proposed protocols are based on CSMA/CD with deterministic collision resolution and belong to the dynamic planning based category, where an admission test is performed for guaranteeing message transmission. This test is based on the worst case channel access time that can elapse before a particular node can transmit its message. We also compute the worst case buffer requirement at the switch. We study the effectiveness of the proposed protocoIs through extensive simulation studies