An Investigation into Transport Protocols and Data Transport ...

3.3. Summary 48
It clearly shows that that the network component is the overriding performance
bottleneck for TCP.
The structure of the graph show that there are certain operating regions
from the results at which the points ‘cluster’. This was found to be a result
of effect of socket buffers (See Section 5.1.1) which limit the physical memory
allocation to TCP, and hence the achievable throughputs.
3.3 Summary
Grid fabric components of storage and network hardware are investigated
and presented in Appendix A. In summary, the tests demonstrate that the
hardware potential for transferring data at greater than Gbit/sec rates is
perfectly feasible.
Test transfers across real production networks were conducted were conducted
using both the stateless UDP protocol and the standard TCP protocol
using memory-to-memory data copying between RAL in the UK and CERN
in Switzerland.
It was discovered that the UDP protocol consistently performed a lot
better than TCP, achieving on average about a factor of 2 difference in
throughput. As much of the Internet traffic relies on the reliable replication
of data across sites, TCP is a fundamental protocol in the performance
of all Internet-based applications. As such, further investigation as to why
TCP is incapable of achieving high throughput transport is warranted.