Virtual cut-through implementation of the HB packet switching routing algorithm

In the last years, since the early 80's, wormhole and virtual cut through routing modalities have replaced packet switching and circuit switching schemes. We give the theoretical bases to implement hole based (HB) routing algorithm (M. Coli and P. Palazzari, 1995) by using the virtual cut through modality. After reviewing the theory of HB routing, we demonstrate some theorems which allow us to use such a theory, developed for the packet switching case, also for the virtual cut through modality (HB-VCT routing algorithm). The main features of HB-VCT are its full adaptivity, the high fault tolerance capabilities and the low HW requirement. Furthermore, low latencies and high bandwidths are achievable because the use of virtual channels can be avoided. Some simulated results are presented in order to show the good traffic balance capabilities and the fault tolerant behavior of HB-VCT. Simulation is also used to show the influence on throughput of traffic intensity and of a HB-VCT control parameter (the timeout).