An Investigation into Transport Protocols and Data Transport ...

7.2. Environment 143
T 0
B, T
T 1
Figure 7.1: Topology of Framework tests for the Evaluation of New-TCP algorithms.
Using the topology illustrated in Figure 7.1, a suite of simple tests was
implemented that exercises the performance of New-TCP algorithms. Even
with the simplicity of this topology, the advantages and disadvantages of
the various New-TCP algorithms can be demonstrated when applied to the
performance metrics oulined in Section 7.1:
Queue-size The importance of how these algorithms perform over a range
of bottleneck queue-sizes is especially important as large BDP’s are
reached due to the hardware limits on the amount of physical memory
on intermediary routers and switches.
Symmetric Network It is expected that all New-TCP algorithms are fair
when identical TCP flows are competed against each other across a
range of different network environments. As a sanity check, it is expected
that all algorithms will achieve higher goodputs than that of
Standard TCP in high bandwidth delay environments, yet should be
able to compete equivalently under low bandwidth delay environments.
Asymmetric Network As higher capacities are introduced into the Internet,
it is important that New-TCP algorithms can scale such that a
flow with larger cwnd does not starve a larger latency (and hence less