Look-ahead traffic distribution in wormhole-routed networks

A new approach, look-ahead traffic distribution, is proposed in this paper to improve the performance of adaptive routing algorithms in wormhole routed networks. In most adaptive routing algorithms, a packet changes its forwarding direction only if its requesting channel is not available, i.e., the routing decision is based only on the traffic information (buffer availability) in adjacent nodes. The performance of these adaptive routing algorithms usually is far from optimal due to such a crude routing decision-making process without taking into consideration traffic information in non-adjacent nodes which a packet potentially is to be forwarded to at a later time. By adding minimal hardware to the router, the proposed approach allows neighboring routers to exchange integrated traffic information and each router to re-integrate information gathered before further propagation. It is intended to use a small amount of such integrated information to give each router a sketch of semi-global traffic information and degree of congestion in an extended local area. Such information is then used for a more intelligent routing decision-making process in each router. Experimental results show that the communication latency and the saturation point have been significantly improved by applying such an add-on feature to existing adaptive algorithms.