弹性分组环业务队长的分析

Queue Length Analysis of Resilient Packet Ring

弹性分组环(ResilientPacketRing,RPR)是刚被IEEE802.17标准化,主要用于城域网的新型MAC层协议,也是宽带IP光城域网技术的重要发展方向。RPR在结构上从属寄存器插入环,其缓存大小的设置对性能的影响很大。目前RPR缓存大小的设置主要借鉴Ethernet、ATM等其它网络的实际应用时经验或仿真结果,尚缺乏理论方面的研究。基于排队论,该文对RPR各缓存里业务的队长及其和吞吐量、节点数目的关系进行研究。所得结果和IEEE802.17所推荐的数值相近;同时还得到一个结论并值得关注:和目前RPR资料文献里的结论不同,理论推导结果表明,队长基本都不是随节点数目成线性关系的。

Resilient Packet Ring(RPR) is a new technology that has just been standardized as IEEE 802.17 for Metropolitan Area Networks(MAN).RPR can be regarded as a buffer(or register) insertion ring.Thus,the buffer size configuration is very important to the performance of RPR.Currently,theoretic analysis of it is lacked for.So,this paper introduces queuing theory to RPR and investigates RPR's queue length and obtains their relations with throughput and number of nodes.The results are close to those of engineering.It also turns out some new points such as queue length does not increase linearly with number of nodes as in the imagination and so on.