A traffic adaptive round-robin algorithm for combined input-crosspoint-queued switches

The appeal of a combined input-crosspoint-queued (CICQ) switch is its distributed scheduling property, which is more scalable than an unbuffered crossbar switch. Round-robin algorithms are interesting because of simple hardware implementation. Although the existing round-robin algorithms achieve 100% throughput asymptotically under uniform traffic, these algorithms have poor performance under nonuniform traffic. In order to improve the performance of a CICQ switch (one cell per crosspoint buffer) under nonuniform traffic, this paper proposes a traffic adaptive round-robin algorithm named TARR. Unlike the existing round-robin algorithms, TARR has distinctive round-robin pointer updating rules which are powerful to cope with nonuniform traffic patterns. On the other hand, TARR is a quantum based algorithm, and the quantum assignment discipline is load adaptive. Extensive simulations show that TARR has a satisfactory performance under both uniform and nonuniform traffic patterns.