| Summary: | 碩士 === 國立成功大學 === 電腦與通信工程研究所 === 93 === Due to the increased address space in IPv6, route capacity and lookup latency become two of the most significant issues for a forwarding subsystem. The prefix length distribution can be quite different when a switching router is applied to the different level of the IPv6 address hierarchy. Hence, if an existing IPv4 routing lookup scheme is used in the IPv6 system, the performance may be degraded due to the variation of prefix length distribution. To reduce the impact of the prefix length distribution, it is necessary to lookup multi-range of the prefix length and perform address lookup in different range of the prefix length simultaneously. Thus, we propose the Three-Set-FLT lookup scheme: setting three range of the prefix length: 24 ~ 47, 48 ~ 55 and 56 ~ 64 to performe address lookup at the same time. The proposed lookup scheme adapts to the variation of prefix length distribution. This scheme employs a parallel CRC compression mechanism to significantly reduce memory size. Our proposed scheme is implemented by two architectures: Multi-cycle and Pipeline. The simulation result shows that the total memory size used is only 21 Mbytes. In the multi-cycle architecture, the average number of memory reference is about 1.5. In the pipeline architecture, the throughput is close to one address lookup per clock cycle when one pipeline is used.
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