Channel grouping techniques in the tandem Banyan switching fabric

With reference to the ATM tandem Banyan switching fabric (TBSF), which is a self-routing output-queued architecture, the concept of channel grouping is investigated according to which packets address a group of network outlets, not a single network outlet. Channel grouping is adopted as a technique to reduce the implementation complexity of the TBSF. In fact by means of the grouping technique a logic two-stage structure can be designed that includes the cascade of a memoryless self-routing switching module and a set of small shared-buffer switching modules connected by means of channel groups. A set of algorithms for grouping the outlets of the routing module is defined such that all the network switching elements apply a packet self-routing rule whose complexity is the same as in the case of absence of channel grouping. Simulations show that the switch performance can be greatly enhanced by means of the channel grouping technique and that it strongly depends on the adopted channel grouping algorithm. Moreover, the same grouping algorithm implies different performances if applied on TBSFs adopting different types of Banyan networks as the basic building block.