An Investigation into Transport Protocols and Data Transport ...

10.1. Summary 247
PCs. But at 1Gb/sec speeds, tests showed almost flawless performances with
CBR UDP traffic.
Chapters 3 through 5 showed that TCP, the primary transport protocol
in use on today’s networks, is incapable of achieving high throughput
transport across high latency, high capacity network environments due to
the standard AIMD congestion control algorithm. Also Chapter 9 showed
that performance limits exist in the TCP protocol due to the processing of
ack and SACK packets.
Several New-TCP congestion control algorithms (Chapter 6) were tested
under various networks and network conditions (Chapters 8 and 9) using a
framework outlined in Chapter 7 which provides a means to comparatively
analyse the advantages and disadvantages of each. Tests specifically investigated
the raw throughput performance achievable and the interaction of
these algorithms both amongst themselves and with legacy Standard TCP.
Even with these New-TCP algorithms, the aforementioned performance
bottlenecks due to hardware and protocol design were apparent and it was
found that the memory to memory transport of data across long distance
high capacity networks is limited to a few hundreds megabits a second under
realistic conditions.
The New-TCP algorithm tests showed that:
• All algorithms are capable of achieving greater raw goodput performance
than that of Standard TCP.
• The interaction between New-TCP flows of various latencies may cause
serious problems in terms of fair sharing of network resources that is
much greater than that of Standard TCP. H-TCP - with its RTT Scaling,
and FAST - with sufficient network buffer are the only exceptions