Implementation of fair link sharing through modification of the Linux kernel

The increasing popularity of sending real-time video data over networks has led to the necessity of controlling the transmission rates of these applications to avoid network congestion. Many algorithms have emerged to control the data rates of video sources. Many of these algorithms do not fairly share available network resources among multiple video sessions, and nearly all of them rely on implicit determination of available bandwidth by monitoring congestion and packet loss. The layered multicast control protocol (LMCP) is a bandwidth control protocol for multicast videoconferencing. This protocol shares network resources between competing video sessions while avoiding the congestion and packet loss of many other algorithms used to probe the network for available bandwidth. Instead, the LMCP relies on router support to determine network resources and share them equally. This paper describes a test bed implementation of a modified version of the LMCP. The implementation involves modification of the Linux kernel to provide the router support necessary for the protocol. We demonstrate the behavior of the protocol in simple network topologies. Our results show that the protocol adjusts to changing network conditions and shares the network bandwidth between competing video applications fairly. A number of issues concerning the protocol still need to be addressed.