|
| |
Uno: a Framework for Deploying Explicit Feedback Congestion Control
Protocols
| Since the bandwidth-delay products of Internet links keep
increasing, issues with TCP's convergence time, throughput, and amount
of queuing in these environments are becoming more pressing. As we move
toward the next-generation Internet, it is important to start
experimenting with congestion control protocols for high BDP networks as
soon as possible. Load-factor based congestion control approach holds
great promise as it requires moderate changes in routers (only to
monitor and insert current load into packets) and endpoints (to use a
congestion controller that uses router feedback). However, existing
proposals either require substantial changes in the IP header (XCP and
most recently, MLCP) that make deployment difficult, or have slow
convergence time and fairness issues (VCP).
UNO is a framework for fine-grain explicit feedback congestion
control protocols that uses only 1 or 2 existing ECN bits, thus making
algorithms that use more than 2 bits for encoding the load factor and
the RTT immediately deployable. UNO accomplishes this task by changing
the way load and RTT information is encoded in packets. UNO takes
advantage of the IP identification field and trades-off small amount of
time (to send several packets) for space to emulate the existence of
several extra bits within the IP header. The results from extensive ns2
simulations over various bandwidth and delay scenarios are encouraging.
By using only one ECN bit we achieve substantially lower convergence
times and better link utilization than the existing deployable
protocols, with similar low queue size and negligible packet loss. With
2 ECN bits, we achieve very good fairness for flows with different RTTs,
while keeping all the good characteristics of the 1-bit protocol. |
|
Publications:
Faculty
Students
|
