单向链路失效下的源路由保护倒换

依据IEEE802.17协议,弹性分组环中所有链路故障都被视作双向链路故障,当环路发生单向链路故障时,为了避免不必要的带宽损失,提出了一种改进的源路由保护倒换方案。利用TP(Topology)帧帧头extended Control域中的保留bit辅助传递链路故障信息,使得环路能够区分单、双向链路故障以便采取最优的重路由操作。分析结果表明:在单向链路故障的情况下,该方案使得环路的故障链路消耗带宽下降了约17%。仿真结果也验证了在单向链路故障下,该方案能够显著提高环路的吞吐量,降低业务的平均延迟时间,并缓解环路的拥塞状况。该方案实现简单,具有很好的应用潜力。

Steering protection switching under unidirectional link failure

According to IEEE 802.17 Standards,all link failures are treated as bidirectional in Resilient Packet Ring(RPR).Therefore,a unidirectional link failure leads to unnecessary loss of bandwidth in the ring.An improved steering protection switching scheme proposed in this article utilizes three reserved bits in the extendedControl field in the TP(Topology)frame header to transfer more failure information.A unidirectional link failure can then be distinguished from a bidirectional failure for more efficient re-routing.Analysis results show that the excessive consumed bandwidth caused by the link failure is reduced by approximately 17%.The simulation results verify that with unidirectional link failures the scheme significantly increases the throughput of the ring,remarkably decreases the mean traffic delay,and reduces the congestion in the ring.The scheme is easy to implement and has many potential applications.