A Leaky Bucket Policing Agent for Site-wide Congestion Control
Teresa L. JohnsonOral Defence Date:
Thursday, August 13, 2009 - 17:00Location:
Professors Murphy, Puder and Wong
Congestion control mechanisms are used by TCP to prevent overflow conditions at intermediate routers. UDP lacks end-to-end congestion control methods and can consume a disproportionate amount of bandwidth compared with TCP. UDP datagrams are dropped if a router on the source-destination path has a buffer overflow. TCP flows through the same router will stop transmitting new segments, thereby giving subsequent UDP traffic an unintended priority. This thesis introduces the design and implementation of a congestion control mechanism that polices both TCP and UDP traffic. This mechanism is designed to smooth out burstyness and to be TCP-Friendly: both UDP and TCP transmission rates are scaled back in a uniform manner. This method is based on a Leaky Bucket algorithm and implemented as a Linux kernel module utilizing the Netfilter framework. Initial experimental results show that this method of congestion control effectively smooths and rate limits both TCP and UDP traffic.