Packet contention is one of the fundamental problems that must be overcome in designing packet switches. In banyan network, which has multistage interconnection structure of many small switch elements, we must be concerned with output port conflicts and internal collisions. Dilated banyan network which provides multiple path for internal link can reduce packet loss due to internal collisions in loss system. However, under hot-spot traffic higher packet loss probability is measured at the hot-spot port and the ports close to the hot-spot as coefficient h increases due to the heavy traffic to hot-spot port. In order to moderate the packet loss probability at the hot-spot port we propose the method to disperse the packets which concentrate on the hot-spot route by altering address field of a half of incoming packets. These packets are switched along detour routes. Thus, the traffic concentration toward hot-spot is mitigated and the packet loss probability at the hot-spot port is moderated.

Input and output queueing nonblocking switch with feed-back loop is proposed in order to reduce the system delay. It has b head of the line (HOL)'s and b output ports feed-backed into the HOL's of feed-back loop. The cell which receives backpressure over threshold is switched and enters one of these HOL's through a feed-back loop. It provides the cell, which should wait behind the HOL of input queue until the cell in that HOL is served, with opportunity to be served immediately by vacating the HOL of the input queue. We obtain the mean system delay and consider the effect of the size of b by computer simulation. As the results, it is shown that proposed switch with appropriate size of b can reduce the system delay compared to the conventional switch.