An experimental study of the Cache-and-Forward network architecture in multi-hop wireless scenarios

The Cache-and-Forward (CNF) protocol architecture was proposed to support efficient mobile content delivery services in the future Internet. In contrast to the TCP/IP protocol stack which is based upon the assumption of reliable end-to-end path through the network, the CNF architecture considers varying access link speed/quality and periods of disconnection as inherent properties of the network. Routers in a CNF network are built with large memory space for in-network caching and temporary storage to support transient disconnections due to mobility or link quality variation. Content delivery through the network follows a hop-by-hop transport method in which files move as single entities from one router to the next rather than as end-to-end packet streams. A novel storage aware routing protocol (STAR) is proposed to efficiently support mobile and wireless end-users through the use of a two-dimensional metric that takes into account both short-term and long-term path quality in making forwarding and storage decisions. A reliable link layer provides per hop file transfer reliability. This paper provides an outline of the three basic protocol components of CNF i.e., transport, routing and link layers and describes a proof-of-concept implementation of the protocol stack on the ORBIT testbed. Performance evaluation results in multi-hop wireless scenarios with lossy link conditions show 66% improvement in wireless network throughput compared to TCP and 60% lower packet loss rate when compared to UDP.