In reference to
"It is probably hopeless to try and adapt TCP in a way
that it handles all of these vastly different link characteristics
optimally
at the same time (this does of course not prohibit certain
optimizations
which are beneficial for specific link types but don't decrease
performance
for others)."
So, this make me think that, more than one TCP may have to exist.
> -----Original Message-----
> From: Stephan Baucke [SMTP:stephan.baucke@eed.ericsson.se]
> Sent: Tuesday, December 15, 1998 5:23 AM
> To: pilc
> Subject: RE: TCP over wireless type links
>
> > It would also be hard to imagine that many link layers will adapt to
> > TCP requirements. It would
> > seem more of a managable problem to have TCP adapt to different link
> > behaviors. Therefore, the
> > suggestion below to have the document include the link layer
> > characteristics of various communication
> > links is a very good one.
>
> TCP is an end-to-end protocol, designed to run over paths which can
> comprise
> several vastly different links at the same time (e.g. it is very well
> possible to have a "long thin" wireless access link, "short fat" wireline
> networks and a "long fat" satellite link in the path your TCP/IP packets
> are
> travelling along). It is probably hopeless to try and adapt TCP in a way
> that it handles all of these vastly different link characteristics
> optimally
> at the same time (this does of course not prohibit certain optimizations
> which are beneficial for specific link types but don't decrease
> performance
> for others).
>
> Assuming this is true, two basic approaches are left: Either you split up
> your TCP connection and optimize TCP on each segment of the path
> individually (split-connection, spoofing, performance-enhancing proxies or
> whatever you call it), or you adapt each individual link so that it
> fulfills
> the assumptions made by TCP. The latter approach seems more sensible to
> me.
> Of course there are certain "hard" characteristics of wireless links which
> cannot be overcome by any protocol, but there are usually some degrees of
> freedom for the designers of link and physical layers (e.g. tradeoff
> between
> FEC and ARQ, channel coding vs. delay etc.).
>
> Stephan Baucke
> Ericsson Research
>
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