An Investigation into Transport Protocols and Data Transport ...

9.3. Internet Transfers 241
achieved goodput is much below this maximum. This is likely to be due
to the the large amounts of traffic that RAL receives and sends due to its
pivotal role as a scientific data centre in the UK.
BicTCP is able to achieve the highest median value, with also the largest
number of low goodput outlier points. It was also able to achieve a very
high value of over 160Mbit/sec demonstrating the capability of the RAL site
under extra-ordinary conditions.
FAST is also able to maintain a high goodput, with a lower quartile which
is almost greater than the upper quartiles of H-TCP and HSTCP. FAST also
has a high minimum range suggesting that the goodput performance would
be greatest with these algorithms.
HSTCP and H-TCP perform very similarly, with HSTCP having a slight
tendency for lower goodputs.
Surprisingly, the goodput of ScalableTCP under this very busy environment
is actually less than that of Standard TCP, although it does have a
slightly higher minimum goodput than that of both HSTCP and Standard
TCP.
Stability
Similarly to the goodput results, Figure 9.38 shows that the stabilities between
all of the TCP algorithms (Standard TCP included) have similar characteristics.
FAST has the smallest inter-quartile range, suggesting the most predictable
stability performance. However, it also has the highest median value
- suggesting that this predictability is not beneficial. It also maintains the
largest number of outlier points.