Congestion Control
for High Bandwidth-Delay Product Networks. Dina Katabi (MIT), Mark Handley (ICSI), Charlie Rohrs (Tellabs) Theory and experiments show that as the per-flow product
of bandwidth and latency increases, TCP becomes inefficient and prone to
instability, regardless of the queuing scheme. This failing becomes
increasingly important as the Internet evolves to incorporate very
high-bandwidth optical links and more large-delay satellite links. To address this problem, we develop a novel approach to Internet
congestion control that outperforms TCP in conventional environments, and
remains efficient, fair, scalable, and stable as the bandwidth-delay product
increases. This new eXplicit Control Protocol, XCP, generalizes the Explicit
Congestion Notification proposal (ECN). In addition, XCP introduces the new
concept of decoupling utilization control from fairness control. This allows
a more flexible and analytically tractable protocol design and opens new
avenues for service differentiation. Using a control theory framework, we model XCP and demonstrate
it is stable and efficient regardless of the link capacity, the round trip
delay, and the number of sources. Extensive packet-level simulations show
that XCP outperforms TCP in both conventional and high bandwidth-delay
environments. Further, XCP achieves fair bandwidth allocation, high
utilization, small standing queue size, and near-zero packet drops, with both
steady and highly varying traffic. Additionally, the new protocol does not
maintain any per-flow state in routers and requires few CPU cycles per
packet, which makes it implementable in high-speed routers. Papers are provided as
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