Working method of prepositive continuous feedback type two-stage switching structure

Abstract

The invention discloses a working method of a prepositive continuous feedback type two-stage switching structure. The two-stage switching structure comprises two stages of crossbar and two stages of caches, an input cache VOQ1 is arranged in front of the first stage of crossbar, and an intermediate cache VOQ2 is arranged between the first stage of crossbar and the second stage of crossbar; and theinput cache VOQ1 and the intermediate cache VOQ2 all adopt a VOQ cache mode. The two-stage switching structure can provide better delay performance during effectively expanding the execution time ofa scheduling algorithm without changing the data transmission control mechanism based on the crossbar or paying additional hardware cost, is compatible with the control mechanism of the existing switching equipment, and can apply the method of the invention to the existing switching equipment at a relatively low cost.

Description

technical field [0001] The invention relates to the technical field of Internet information transmission, in particular to a working method of a front-end continuous feedback two-stage switching structure. Background technique [0002] At present, the data forwarding rate of switches and routers is far lower than the data transmission rate of optical fiber, which makes network relay equipment become the bottleneck of Internet data transmission bandwidth; the key factors affecting the forwarding capabilities of switches and routers are the switching structure and its Scheduling algorithm; in order to increase the data forwarding rate of network equipment as much as possible, the network and communication industry have carried out relevant research from the perspective of switching structure and its scheduling algorithm; due to the self-similar nature of Internet data streams, traditional switching structures such as IQ , CICQ, etc., in the self-similar business flow environme...

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Problems solved by technology

[0002] At present, the data forwarding rate of switches and routers is far lower than the data transmission rate of optical fiber, which makes network relay equipment become the bottleneck of Internet data transmission bandwidth; the key factors affecting the forwarding capabilities of switches and routers are the switching structure and its Scheduling algorithm; in order to increase the data forwarding rate of network equipment as much as possible, the network and communication industry have carried out relevant research from the perspective of switching structure and its scheduling algorithm; due to the self-similar nature of Internet data streams, traditional switching structures such as IQ , CICQ, etc., in the self-similar business flow environment, its switching performance deteriorates rapidly with the increase of the load rate; the load balancing structure proposed by C.S.Chang et al. can effectively distribute the burst data flow that reaches the input end evenly to the second-level cache; thus It can better adapt to the self-similar business flow, but the structure has two problems of unsatisfactory performance and out-of-sequence of cells; in view of this problem, Hu Bing et al. proposed a two-level switching structure FTSA based on the feedback mechanism, such as figure 1 As shown; FTSA provides the buffer queue status data at the target port to the input port as the basis for scheduling through the feedback mechanism of the intermediate port, thus obtaining a relatively ideal delay performance; at the same time, its special crossbar connection mode can also avoid cell Out of sequence at the output; however, FTSA requires the scheduling algorithm to be completed within the crossbar reconfiguration time; the crossbar reconfiguration time depends on the switching speed of electronic components, which takes about nanoseconds in terms of today's microelectronics technology; and Conventional algorithms such as RR, LQF, and EDF need to compare N times in the worst case, which makes the excellent theoretical performance of FTSA practically unachievable

[0003] The existing solution FFTS (2010102782679) realizes the extension of the execution time of the scheduling algorithm by advancing the feedback time to the beginning of each time slot; The problem of cell conflict occurs; to solve these problems, FFTS adopts a double cell buffer mode, and needs to set a reordering buffer on the output port to adjust the order in which cells leave the switch; this makes FFTS pay attention to solving the execution time limit of the FTSA algorithm It reduces the cost of complication of switching structure and switching process, sharp increase of hardware overhead and deterioration of delay performance

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