一种保证服务质量的大型CICQ交换结构

A CICQ Switch with Large RTT for Providing QoS Guarantees

现代包交换机需要具有为不同的数据流提供不同的服务质量(QoS)的能力,同时随着网络规模和业务的增长,交换机的线卡数目会大量增加,线卡和交换矩阵需要分布在多个线柜中,它们之间的距离可能达到数十米,因此在设计交换机时不能忽视交换机内部的往返时延(RTT).该文从这两个方面来讨论支持大RTT的组合输入和交叉点缓存排队(CICQ)交换结构实现服务质量保证问题,提出了基于扩展交叉点缓存的支持大RTT并提供基于流的性能保证的CICQ(CICQ-ECBs)交换结构,给出解除扩展交叉点缓存(ECB)阻塞机制,并用Counting方法证明了2倍加速的CICQ-ECBs交换结构能够实现PIFO-OQ仿效.

Modern switches need to have the capability of providing QoS guarantees for different applications.On the other hand,to ac commodate the growth of the Internet traffic,the current packet switch supports a large number of ports requiring a large number of line cards.Line cards and switch fabrics are distributed in multiple cabinets.The interconnection between the line cards and the switch fab ric may be tens of meters apart.Therefore the round-trip time(RTT)delay internal to the switch cannot be neglected in designing the fu ture packet switches.The output-queued switch emulation by a Combined Input-Crosspoint Queued(CICQ)switch with large RTT was discussed in this paper.A CICQ switch which provides flow based performance guarantees with extended crosspoint buffers(CICQECBs)was proposed for large RTT.An ECB unblocking mechanism for CICQ-ECBs was described.The counting method was used to prove that the CICQ-ECBs switch with two times speedup can exactly emulate a push-in-first-out(PIFO)OQ switch.