Device Constraint Of Clos Network Path Research And Design In Large Capacity Optical Switches

Due to the ever-accelerating development of Internet new applications, the dataflow of network increases significantly, so individuals strongly hope that the capacity ofelectric switches could be raised considerably. Unfortunately, it is difficult to enlarge thecapacity for the sake of the increase of wire’s transferring rate, the bottleneck ofswitching rate, the heat dissipation and the power loss. Based on the low loss and abilityof carrying transferring signal with high rate, the Pbps ultra-large capacity switchesdesigned in this paper use fiber link to realize the interconnection and switchingbetween electric-exchange backplanes. The power consumption is decreaseddramatically and the network capacity is improved.Firstly, the development requirements and current situation of domestic andinternational researches about fiber switches with super large capacities is illustrated bythis paper. Secondly, networking switching structure inside the fiber switch is analyzed.Thirdly, existing device constrain conditions of electric switches is demonstrated.Finally, switching and dispatching algorithm is expressed in detail.The optical switching structure based on FTL and AWG is an optimum choice thatcan realize the goal of optical switches with super large capacities. However, the rapidtuning requires of FTL make idle FTL keeping lighting, and interrupt optical signalswith valid demands. To solve this problem, a method, using invalid demands to occupyidle time slot, is proposed, so that the valid demands in the system will not interruptedby invalid demands.Firstly, a method named random strategy is proposed to generate the invaliddemands, which make none idle demand in the network, and therefore, it eliminatesthose constrains from FTL. Taking this as fundament, then another method to generatethe invalid demands called sequential strategy was proposed. Due to the sequencecharacter in the network, using sequence strategy under a specific demand quantity willsave system’s operating time and decrease system’s number of rearrangement. Thereprovides compared simulations of two strategies under different demand quantities, andcomparing them in terms of system’s operating time and the number of rearrangement of inner network.The provided one-way routing strategy used for route selecting for invaliddemands mainly uses the character that invalid demands will not need to recoverdemand data at receive point. Invalid demands then are made only needing fixed inputpoint, choosing output point randomly based on idle routes in the network. But in thenetwork, A specific number of lights are allowed by devices to enter the devicessimultaneously while not allowed to send all invalid demand signals to one point. Inorder to avoid the damage of optical burst receivers caused by overreaching invaliddemands light signals, it is useful to make a threshold constrain for the number ofsimultaneously accepted invalid demand signals in every idle output point. In this essay,a threshold-based strategy is given, and a comparison is provided based on system’soperating time and the number of rearrangement of inner network between two differentstrategies.