IP-in-IP tunneling to enable the simultaneous use of multiple IP interfaces for network level connection striping

With ubiquitous computing and network access now a reality, multiple network conduits are become widely available to mobile as well as static hosts: for instance wired connections, 802.11 style LANs, Bluetooth, and cellular phone modems. Selection of the preferred mode of data transfer is a dynamic optimization problem which depends on the type of application, its bandwidth/latency/jitter requirements, current network conditions (such as congestion or traffic patterns), cost, power consumption, battery life, and so on. Furthermore, since wireless bandwidth is likely to remain a scarce resource, we foresee scenarios wherein mobile hosts will require simultaneous data transfer across multiple IP interfaces to obtain higher overall bandwidth. We present a brief overview of existing work which enables the simultaneous use of multiple network interfaces and identify the applicability as well as strengths and weaknesses of these related approaches. We then propose a new mechanism to aggregate the bandwidth of multiple IP paths by splitting a data flow across multiple network interfaces at the IP level. We have analyzed the performance characteristics of our aggregation scheme and demonstrate significant gains when the network paths being aggregated have similar bandwidth and latency characteristics. In addition, our method is transparent to transport (TCP/UDP) and higher layers, and allows the use of multiple network interfaces to enhance reliability. Our analysis identifies the conditions under which the proposed scheme, or any other scheme that stripes a single TCP connection across multiple IP paths, can be used to increase throughput.