EQuB-Ethernet quality of service using black bursts

Abstract

EQuB is an overlay mechanism to Ethernet's MAC protocol that provides QoS guarantees to real-time applications. In its basic form, EQuB relies on the sensing and collision detection abilities of standard network interface cards and, in addition, requires only that those cards be capable of sending jam signals-so called black bursts-of pre-specified durations. EQuB gives access priority to real-time traffic, provides round-robin service among real-time hosts and guarantees a small, bounded delay to real-time packets. We also discuss enhancements to the basic EQuB mechanism that improve its performance. Simulation results are presented that assess the performance of 10 and 100 BASE-T Ethernet LANs with a mixed population of data and real-time hosts. We conclude that, in spite of the priority, attained by real-time traffic, data packer delays are not significantly affected as data load is traded for real-time load, and this is because EQuB dispatches packets to the channel much more efficiently than Ethernet's MAC protocol.