ATM Switching with Minimum-Depth Blocking Networks Architectures and performance of interconnection networks for ATM switching based on the adoption of banyan networks are described in this chapter. The interconnection networks presented now have the common feature of a minimum depth routing network, that is the path(s) from each inlet to every outlet crosses the minimum number of routing stages required to guarantee full accessibility in the interconnection network and to exploit the self-routing property | Switching Theory Architecture and Performance in Broadband ATM Networks Achille Pattavina Copyright 1998 John Wiley Sons Ltd ISBNs 0-471-96338-0 Hardback 0-470-84191-5 Electronic Chapter 6 ATM Switching with Minimum-Depth Blocking Networks Architectures and performance of interconnection networks for ATM switching based on the adoption of banyan networks are described in this chapter. The interconnection networks presented now have the common feature of a minimum depth routing network that is the path s from each inlet to every outlet crosses the minimum number of routing stages required to guarantee full accessibility in the interconnection network and to exploit the self-routing property. According to our usual notations this number n is given by n log bN for a network N X N built out of b X b switching elements. Note that a packet can cross more than n stages where switching takes place when distribution stages are adopted between the switch inlets and the n routing stages. Nevertheless in all these structures the switching result performed in any of these additional stages does not affect in any way the self-routing operation taking place in the last n stages of the interconnection network. These structures are inherently blocking as each interstage link is shared by several I O paths. Thus packet loss takes place if more than one packet requires the same outlet of the switching element SE unless a proper storage capability is provided in the SE itself. Unbuffered banyan networks are the simplest self-routing structure we can imagine. Nevertheless they offer a poor traffic performance. Several approaches can be considered to improve the performance of banyan-based interconnection networks 1. Replicating a banyan network into a set of parallel networks in order to divide the offered load among the networks 2. Providing a certain multiplicity of interstage links so as to allow several packets to share the interstage connection 3. Providing each SE with internal .
