Minimization of flow table for TCAM based openflow switches by virtual compression approach

Forwarding lookup in the open flow switch can be done for each arriving packet by every switch in path. Every switch maintains a set of IP prefix value in its lookup table. For a given IP address it finds a longest prefix match in the forwarding table that matches first fewer bits of destination address. Earlier, there are several technique that has been proposed to optimize the table space and to reduce the number of entries in the forwarding table. In TCAM prefix values needs to be stored in descending order of its length, it require more number of entries needs to be shifted. In this paper we propose a method to reduce the length of the prefix value up to 50 to 60% horizontally as well as vertically which will be stored in the forwarding table. It involves significant prefix methods to reduce number of entries in the forwarding table.