Seminars & Colloquia
UNC Chapel Hill
" RAPID: RTT-fair Congestion-control for Terabit Networks"
Thursday January 29, 2009 02:00 PM
Location: 3211, EB 2 NCSU Centennial Campus
(Visitor parking instructions)
We argue that the legacy design framework of window-based transmission and control, that fundamentally operates at an RTT timescale, is responsible for this poor scalability behavior. We design a new rate-based framework for congestion-control that allows TCP connections to boldly search for, and adapt to, the available bandwidth within a handful of RTTs. Our key insight is to rethink the timescale at which congestion-control probes for available bandwidth---we show that by shrinking this timescale, it is possible to design a protocol that achieves a high bandwidth-search speed without significantly overloading the network. Our resultant approach relies on carefully orchestrated inter-packet gaps at the sender---that help quickly probe for several different rates using only a few packets---and estimates the available bandwidth based on gap increases at the receiver.
We use this framework to design a new protocol, referred to as RAPID, using mechanisms that promote efficiency, queue-friendliness, and fairness. Our experimental simulations with 1-10Gbps networks indicate that RAPID: (i) converges to an updated value of bandwidth within 1-4 RTTs; (ii) is fairly efficient in utilizing rapidly-varying spare bandwidth; (iii) helps maintain fairly small queues; (iv) has negligible impact on co-existing conventional TCP traffic aggregates; and (v) exhibits excellent fairness among co-existing RAPID transfers. The rate-based design allows RAPID to be truly RTT-fair.
Jasleen received her B.Tech. in Computer Science and Engineering from the Indian Institute of Technology, Kanpur, in 1997, where she was also awarded the Motorola Student of the Year Gold Medal. She earned an M.S. and Ph.D. in Computer Sciences from the University of Texas at Austin in 1999 and 2002, respectively. She is a recipient of the J.C.Browne Graduate Fellowship and the M.C.D. Fellowship from the University of Texas at Austin.
Host: George Rouskas, Computer Science, NC State