[e2e] Question on TCP throughput and host's access speed

[Dennis Rockwell]

On 14 Oct, Jing Shen wrote:

> We use two leased line from ISP. One is a 2Mbps ADSL
> the other is a 100Mbps fiber link. [ ... ]

> packet loss and retransmission happen more frequently
> when I use Fiber link.

Retransmissions kill TCP throughput rather thoroughly,
especially in long (high delay) paths.

> Analizing routing path between
> our computer and server in jappan, we found there is
> no difference between ADSL access and Fiber Link
> beside the access method.

What you have discovered is that your 2Mbps link is not the
bottleneck; that lies elsewhere in your network path.  The
extra bandwidth of the fiber link cannot help this
application.

Good luck!

Dennis