Comparative study of inner congestion control mechanisms in terabit routers

More and more attention is focused on direct interconnection networks when designing the switching fabrics in the terabit routers. Various congestion control mechanisms are proposed for multi-computer systems, which also rely on direct interconnection networks between processors to support the messages passing mechanism. But it remains unknown whether they are suitable for fabrics in the terabit routers. Based on the requirements of terabit class routers, we made analysis and simulations on various congestion control mechanisms, such as U-channel, INC, self-tune and GRCC. The results show that congestion control mechanisms eliminate performance degradation for loads beyond saturation, keeping adequate levels of throughput at high loads. The local mechanisms can achieve similar performance with the global ones. However, as we pointed in the paper, they all have limitations when used in switching fabrics of the terabit routers.