Emad,
Are you planning to simulate variants of transports other than those based on
TCP?
Alex
-------------------
Dr. A. B. Cannara
Network Consulting Services
Menlo Park, Ca.
Emad Qaddoura wrote:
>
> 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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