1COCOON: An Alternative Approach to End-Point Congestion Management

Abstract — In this paper, we propose an alternate endpoint congestion management scheme, called CO-ordinated COngestion cONtrol (COCOON). The basic idea is to identify and group connections that may traverse the same backbone link, to enable them to share congestion information, and to coordinate among them all the congestion avoidance/control activities. The size of a COCOON group can be dynamically adjusted so as to magnify the benefits of end-host congestion management. COCOON also allows a new connection to commerce with a con-gestion window that is large enough to catch up with other connections while not inducing congestion. Finally, COCOON takes into account non-responsive UDP connections and “bundles ” them into a virtual connection that is subject to TCP-like congestion control. Both our ns-2 simulation and FreeBSD empirical studies indicate that as compared to other existing schemes such as TCP-Reno, TCP-Int, Congestion Manager, HTTP 1.0 and HTTP 1.1, COCOON sig-nificantly reduces the packet loss ratio of concurrent connections, while sustaining the throughput compa-rable to the best scheme. This, coupled with the fact that COCOON requires only minor modification at server hosts, suggests that COCOON can be readily deployed over the Internet. Index Terms — End-point congestion management