Real-Time Schedulability of Two Token Ring Protocols

mn d e n y ? . &-time c o m m u n k t i o n protocols, the pnmary o jec tve i s to guamntee the deadlines of c h m n o w messages whale sustaming a high a m a t e Z u g h p t . In this stud we wmpunz two t o h n ring pmtoco for their suitadkt in h a n i d t i m e system. A priority driven protocol(!g. IEEE 802.5) allows amplementatiqn o a priority bas+ d t t m e scheduling token protocol (q. FDDI) provides guaranteed bandwidth and bounded abcess tame for s chronoua mess es. W e study these two protocolsg deriving their SKeduiabirity oite+ i e . , the conditions which determine whether a p e n mess e set can be guaranteed. Uaing these critericr, we ev8uate the avemge performana of these protocols under different o mting conditions. W e observe that neither prvtocol g m i n a t e s the other for the entire range of w e conclude that the pnority ?riven protocol per&% better at low bandwidths (1-10 Mbps) while the timed tot m l has a superior performance at higher band%E dimplane lske &e rate monotonac algonthm. A ttmed