Patent ID: 6885669

Claim:
A network having a plurality of multicast connections, said network comprising: an input stage comprising r 1 input switches, and n 1 inlet links for each of said r 1 input switches; an output stage comprising r 2 output switches, and n 2 outlet links for each of said r 2 output switches; and a middle stage comprising m middle switches, and each middle switch comprising at least one link (hereinafter “first internal link”) connected to each input switch for a total of at least r 1 first internal links, each middle switch further comprising at least one link (hereinafter “second internal link”) connected to each output switch for a total of at least r 2 second internal links; said network further is always capable of setting up said multicast connection by changing the path, defined by passage of an existing multicast connection, thereby to change one or two middle switches used by said existing multicast connection, and said network is hereinafter “rearrangeably nonblocking network”, where m is a minimum of at least n 1 +n 2 .