Page1    Page122                                                                        Page124  Page177

0.018

0.017

0.016

NS-2

0.015

Static link model

Joint link model

0.014

Integrator link model

0.013

DAE link model

0.012

0.011

0.01

25

25.5

26

26.5

27

Time [sec]

Figure 75: Result of algebraic link model studies showing conditions under which FAST,

which is normally very stable, can be made to oscillate. The results are compared to NS-2

simulations

The above model was used to determine conditions under which FAST causes the data rate to

oscillate. Experiments in these conditions demonstrate that FAST causes the rate to oscillate less

than standard TCP, and less than most proposed replacements.

MaxNet and ADPM:

Work has also been put into the design and implementation of the MaxNet TCP network

congestion control protocol. MaxNet uses explicit multi-bit signaling from routers to achieve high

throughput and low latency over networks of arbitrary capacity and topology and virtually any

delay. MaxNet also overcomes a major problem with the current TCP, namely that short flows

start transmitting too slowly, hampering interactivity. The MaxStart algorithm allows MaxNet to

fill the transmission pipe with data just one round trip time (RTT) after the first packet.

The MaxNet algorithm has recently been extended to give both provable stability and rate

fairness [4], [5]. The implementation is based on the Linux Traffic Control framework. The

system consists of a sender and receiver TCP algorithm as well as a router module. Performance

has been tested for capacities up to 1Gbit/s and delays up to 180 ms using the WAN-in-Lab

facility. With no overhead but 24-bit price signals, MaxNet can scale from 32 bit/s to 1 Peta-bit/s

with 0.001% rate accuracy.

123