Wide-sense nonblocking for multirate 3-stage Clos networks

The 3-stage Clos network C(n,m,r) in the multirate environment has recently been studied for strictly nonblocking and rearrangeably nonblocking, but not much is known for wide-sense nonblocking. This is not really surprising since very little is known about wide-sense nonblocking even for the classical circuit switching environment. In this paper, we propose a class of ''quota'' algorithms and show that by using such an algorithm the number m of center switches required is always less than that for strictly nonblocking. In particular, when no bound is set for the rate (except it is greater than zero and not exceeding the link capacity), then m required for strictly nonblocking is unbounded, while 5.75n suffice for our algorithm. Better results for the 2-rate and 3-rate environments are also obtained.