Wave and Equation Based Rate
Control Using Multicast Round Trip Time. Michael Luby, Vivek
K Goyal (Digital Fountain), Simon Skaria (UC Irvine), Gavin B. Horn (Pulsent). This paper introduces Wave and Equation Based Rate Control
(WEBRC), the first multiple rate multicast congestion control protocol to be
equation based. The equation-based approach enforces fairness to TCP with the
benefit that fluctuations in the flow rate are small in comparison to TCP. This paper also introduces the multicast round trip time
(MRTT), a multicast analogue of the unicast round
trip time (RTT). The MRTT is fundamental to the equation-based protocol that each
receiver uses to adjust its reception rate. Each receiver independently
measures its own MRTT without placing any added messaging burden on the
receiver, the sender or the intermediate network elements. Benefits provided
by the MRTT include those that the RTT provides to TCP, e.g., reduced
reception rates in reaction to buffer filling and fair sharing of bottleneck
links. In addition, the use of MRTT is shown to synchronize and equalize the reception
rates of proximate receivers and to cause reception rates to increase as the
density of receivers increases. Another innovation of WEBRC is the idea of transmitting
data with waves: the transmission rate on a channel is periodic, with an
exponentially decreasing form during an active period followed by a quiescent
period. Benefits of using waves include insensitivity to large IGMP leave
latency; a frequency of joins and leaves by each receiver that is small and
independent of the receiver reception rate; the use of a small number of
multicast channels; fine-grained control over the receiver reception rate;
and minimal, at times nonexistent, losses due to buffer overflow. Papers are provided as
a service to all by the members of ACM SIGCOMM. This
paper is available in Adobe PDF format. |