Research And Implementation Of Key Reinforcement Technologies For Forwarding Information Base In On-board Router

The emergence of on-board router changed the traditional communication mode in space, and simplified the process of satellite communication, has the milestone significance. With the continuous development of space communication technology, the role of on-board router is more and more important. Due to the advantages of high performance, flexible configurability and short design cycle, FPGA has changed the traditional development mode of digital circuit, and gradually becomes the core component of space electronic equipments. However, the harsh space environment is filled with all sorts of high-energy particles, which caused great threat to the security of space devices. Meanwhile with the increase of chip integration, the noise margin of device has reduced gradually, and the chips become more sensitive to single event effect(SEE). Therefore, in addition to having high performance itself, the on-board router has to resist the impacts of SEE.This paper is mainly aiming at the reinforcement of forwarding engine in on-board router, and forwarding information base(FIB) is the core of the forwarding engine. The FIB in this paper is based on FPGA on-chip memory——block RAM, and the block RAM is quite sensitive to SEE, so we need to choose specific reinforcement mechanism according to its characteristics. The main work and innovations in this paper are as follows:Firstly, based on the different types and influences of SEE, and the characteristics of the RAM-type forwarding table, this paper puts forward the corresponding reinforcement mechanism with the combination of redundancy and scrubbing. Among them, we did EDAC(Error Detection and Correction) encoding to the forwarding table entries, and TMR(Triple Modular Redundancy) to the encoding and decoding modules, also combined the redundancy with corresponding scrubbing mechanism at the same time, this can maximize the ability of forwarding table to resist the influences of SEE.Secondly, EDAC coding is realized by extended Hamming code, this code can be simply realized with less check bits and can effectively achieve SEC/DED(Single Error Correction/Double Error Detection), is suitable for the encoding of RAM memory cell. According to the features of forwarding table based on dual-port RAM, we adopt the scrubbing mechanism combining the Passive Scrubbing and the Active Scrubbing, the former one includes local scrubbing and external scrubbing, the latter one includes scrubbing with adjustable rate and partial FIB scrubbing. This scrubbing mechanism can effectively improve the correctness of the data in FIB.Thirdly, aiming at the reinforcement mechanism put forward in this paper, we did the verification on the Net Magic network experiment platform. Simulating the error cases caused by SEE through fault injection, we tested the redundancy and scrubbing mechanism respectively. The test results show that, by adopting the combined strategy of redundancy and scrubbing in this paper, all kinds of faults can be effectively mitigated, and it has less influence on the performance of forwarding engine, and a favorable effect in practical application.In summary, this paper deeply researches the forwarding table based on FPGA on-chip memory, proposes the corresponding reinforcement mechanism combining redundancy with scrubbing according to its characteristics, and verifies the validity and practicability of this mechanism through experiment. Part of the work in this paper has been applied in actual engineering, and has certain reference significance to the reinforcement problems of space forwarding engine.