Hybrid trie based partitioning of TCAM based openflow switches

Abstract

The packet forwarding mechanism in the open flow network switch is based on the IP lookup in the forwarding table, which consist of the destination IP address of the incoming packet. In general, these forwarding tables are Content Addressable Memory (CAM), where the desire key will be searched in the table to know out going port. Ternary content addressable memory (TCAM) is one of the efficient mechanism to store the forwarding table, where values are stored in sorted order. Search of any key is done by using longest prefix matching technique. It uses 0, 1 and x (don't care) to represent the data, rather using 0 and 1 in case of CAM. The major drawback of TCAM is that it is a power hungry circuit. Today's high-density TCAMs consumes 12 to 15 Watts of power per chip, when the entire memory is enabled. This paper proposes an efficient representation of data in the forwarding tables and search algorithm which takes the algorithmic time complexity is O(loglog n). This paper also proposes an efficient way to reduce the index TCAM size by using y-Fast trie-partitioning algorithm.