STRICTLY NONBLOCKING MULTICAST MULTI-STAGE NETWORKS

摘要

A three-stage network is operated in strictly nonblocking manner in aeeordance with the invention includes an input stage having i] switches and //, inlet links for each of r, switches, an output stage having r, switches and /;, outlet links (breach of r, switches. The network also has a middle stage of m switches, and each middle switch has at least one link connected to each input switch fora total of al least /; first internal links and al least one link connected to each output switch for a total of at least /•, second internal links, where m 2*/;, i /;, 1 . In one embodiment, each multicast connection is set up through such a three-stage network by use of at most two switches in the middle stage. When the number of inlet links in each input switch /;, is equal to the number ol outlet links in each output switch //,, and //, //, /;, a thrcc-slage network is operated in strictly nonblocking manner in accordance with the invention if /// -•• 3 * n 1 . Also m accordance with the invention, a three-stage network having more middle switches than 2*//, i /;, 1 is operated in strictly nonblocking manner even if some multicast connections are set up by using more than two middle switches as long as each connection has available links into at least two middle switches and there are always at least ii, 1 unused links from each input switch to middle switches, after each connection is set up