An Investigation into Transport Protocols and Data Transport ...

6.3. Summary 133
6.3 Summary
The recent rise of high performance networks and long latency links has lead
to the visible deterioration of TCP performance in real life situations. As
such, there has been much interest in the transport community in the need
to replace the standard TCP congestion control algorithms with something
that is capable of attaining reasonable throughput under realistic network
conditions.
A question arises over the manner in which deployment should occur. As
these protocols have never been widely tested in real network environments, it
is difficult to determine whether there are potential hazards to running these
New-TCP algorithms on the Internet. Whilst running a single flow through
the Internet is unlikely to cause problems, the aggregation of many flows
may. The problem lies in the possibility of lock-out and severe unfairness
that will prevent competing users from sharing network resources. However,
the modeling of such systems prove very difficult to do realistically [AF99]
due to the heterogeneity of the Internet.
Many of the proposals presented often cite the inclusion of AQM to mitigate
the potential problems that aggressive algorithms may pose. [FJ93]
states that AQM should be implemented, however, this is often far from the
truth as most networks on the Internet still employ drop tail queuing. Therefore,
when it comes to the question of the near term deployability of such
protocols, special attention should be given to ensure that it is not dangerous
to use such congestion control algorithms now.
The other question is which New-TCP algorithm should people use? Each
protocol appears to have distinct advantages and disadvantages; for example,
ScalableTCP ensures that high capacity can be attained regardless of network