An Efficient CICQ Switch Architecture for Mixed Unicast & Multicast Traffic

Abstract

Recently multicast is increasingly required for various media applications such as IPTV, teleconferencing, E- Learing etc. Accordingly, the unicast and multicast traffic flows coexist in the Internet and how to deal with these two types of traffic is an upcoming issue of today's network evolution. In this environment, existing combined input and crossbar queued (CICQ) switches are not applicable to provide QoS for multicast traffic due to the large delay introduced by high occupancy of crosspoint buffers by unicast traffic. Moreover, head-of-line (HOL) blocking problem is hard to be solved especially for multicast traffic. In this paper, we propose virtual threshold for CICQ switch (VT) scheduling scheme to prevent interruption of multicast cell storing to the crossbar buffer which is caused by higher buffer occupancy of unicast cell. Also we suggest an enhanced buffered crossbar switching architecture with extra queue to solve the HOL blocking problem of multicast cells which is called extra multicast virtual output queue (EMVOQ). The simulation results show that CICQ switch with proposed VT and EMVOQ achieves great delay reduction of multicast traffic.