An Investigation into Transport Protocols and Data Transport ...

9.1. Transfer Tests Across Dedicated Private Wide Area Networks 191
Two projects that have aided in the facilitation of understanding high
speed network transport are the cross-UK MB-NG development network (See
Appendix C.2) and the transatlantic DataTAG testbed (See Appendix C.3).
Both networks were configured to provide a link capacity of 1Gbits/s and
the performance of New-TCP algorithms was investigated.
9.1.1 Methodology
A series of tests were conducted to analyse the performance of New-TCP
flows at 1Gb/sec on the DataTAG and MB-NG testbeds. The two extremes
of latencies available with these two networks enable analysis of the cwnd
dynamics of New-TCP. DataTAG provides the high capacity, high latency
networks at which Standard TCP fails and these algorithms are designed to
operate, whilst the low latencies of MB-NG can provide information regarding
the switch between the low and high speed mode of these algorithms.
At the time of the testing only HSTCP, ScalableTCP and H-TCP had
been proposed and were therefore available for testing. As such, the results
within this section are limited to only these New-TCP algorithms.
iperf [TQD + 03] was used to initiate TCP flows that simulate bulk transfer
using standard IP packet sizes of 1500B. All machines used in the tests
were installed with the altAIMD kernel version 0.3 and were run with Appropriate
Byte Counting (See Section 5.2.4) with local host buffers set to
sufficiently large values as shown in Table B.2 to ensure that performance
bottlenecks did not exist in the end-host systems.
All flows were also configured with sufficient socket buffer allocation to
prevent host-based flow control and each test was repeated at least three
times to determine an appropriate standard error.