Fw: [e2e] overlay over TCP

[Alex Cannara]

As the archives for this list should show, there's more to typical TCPs' 
behaviors than most people think.  And, very few folks have done much to 
examine real TCP flows in real situations.  TCP has an Achille's heel with 
some interesting performance facets, which real-world experimentation quickly 
reveals.  The imagined benefits of various 'sophisticated' TCP algorithms pale 
when the simplest of things happen on a real link, such as loss, or even just 
the sending of an odd number of payloads per application block.  One test for 
anyone who claims TCP expertise is to have that person estimate the effect of 
1% packet loss on time to transfer a sizeable file.  We can then move on to an 
estimate of the negative effects of Delayed Ack, etc.  In other words, 
stopping significant Internet protocol development over 20 years ago was a 
mistake we pay for every day in every business now.  But hey, we've settled 
for lots of other mediocrities.

Alex

Dave Crocker wrote:

> On Thu, 20 Jan 2005 16:51:09 -0500, Paul D. Amer wrote:
> 
>>  FTP can run over SCTP, and in fact can perform better
>>  than FTP running over TCP.
> 
> 
> "Perform better" has some significant pre-conditions, here.
> 
> The savings of the work you cite are primarily in transition latencies (from connection setup and command lock-step performance.)
> 
> For a single transfer of a large file, this enhancement is irrelevant.  The data transfer portion washes out any command or transition overhead.
> 
> For a single transfer of a small file, this enhancement is irrelevant. Everything is so quick, making the control and transition mechanism quicker doesn't really make any difference.
> 
> In fact the savings are only interesting in the case of having a large number of small files to transfer.  In this case, the "control" overhead will tend to dominate, so that optimizing it is indeed a Good Thing.
> 
> 
> d/
> --
> Dave Crocker
> Brandenburg InternetWorking
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>