Terabit per second atm packet switch having out-of-band control with

Abstract

An out-of-band controller for a large packet switch which is distributed throughout partitions or pipes of the packet switch. Thus, the out-of-band controller is divided into multiple pipe controllers. These pipe controllers are connected and operated in a ring such that each pipe controller is with a respective fraction of the input path requests for packets. The requests are processed concurrently and any request that is not fulfilled in one pipe controller is offered to up to three subsequent pipe controllers to hunt a path for the awaiting packets. The controller, by using up to four levels of parallelism, can hunt paths and set up connections for 256 or more input ATM packet lines in normal monocast mode, thus providing a throughput of 1 terabit per second or more. A distributed controller design makes such tremendous aggregate switching speeds possible. The same general distributed controller design can also provide pipe hunting for a special packet operation called multicasting, in which one packet from one input line is transmitted to many or even all output lines. As can be appreciated, multicasting can monopolize system assets to the detriment of other ATM packets, so some multicasting may be made during special packet cycles when primarily multicasting packets will be carried. One such special packet cycle might occur at system initialization.