Trie shifting scheme with depth adjusting for multiple virtual routers

In network virtualisation, which enables multiple virtual routers to share one physical router, how to ensure the scalability and performance of concurrent virtual routers is a challenging problem in virtual router design. Since physical router only has limited memory resource, it is significant to efficiently store multiple forwarding tables for virtual routers. Motivated by the idea of diminishing the dissimilarities in forwarding tables, the authors propose a novel trie shifting scheme with depth adjusting, and finally obtain a memory-efficient shared trie for all forwarding tables. In this scheme, by diminishing the dissimilarity in the depth and in the shape, memory is saved by reducing the trie nodes needed in the shared trie. In the simulation, the scheme needs only 10% of trie nodes, compared with storing forwarding tables separately. Extensive simulation based on three sets of forwarding tables, which are collected from five backbone routers, shows that the scheme saves memory by reducing the number of trie nodes between 4.7 and 7.8%, compared with the latest scheme in related work. Moreover, this scheme achieves more improvement when the dissimilarity is increasing.