Subject: Re: Comments to "Advice for Internet Subnetwork Designers"

From: Vernon Schryver <[email-masked]>
Date: Mon, 24 Jul 2000 07:53:40 -0600 (MDT)

> From: Reiner Ludwig <[email-masked]>

> ...
> > > How can you specify with the existing DSCPs/PHBs that a flow (more
> > > precisely the application on top) is best served with max throughput and
> > > max reliability?
> >
> >As you wireless people keep pointing out, you can't maximize both
> >simultaneously without failing to maximize one or the other.

> ...
> But, I can run my wireless link with maximum error recovery persistency 
> (i.e., max reliablity) but with FEC A for telnet to minimize delay and FEC 
> B for ftp to maximize throughput.

But you are not maximizing throughput and reliability.  As some of the
wireless people tirelessly point out (especially some with addresses at
Ericsson.com), you could get more throughput by not using any FEC, not to
mention the retransmissions. I assume you mean by "error recovery
persistency."  

> ...
> >If the people running the edges where the new DS bits are changed
> >do stupid things, then bad things will happen to the applications that
> >rely on the new DS bits, or at least they not use the new DS bits.
>
> Exactly, and that's the problem I see. Again, I wish we could have DSCPs 
> with e2e semantics.

You can't pass laws or standards that keep people from doing stupid things.
In other words, why not continue to mark your FTP/TCP/IP packets with 0x08
and their telnet packets with 0x10?  (I trust you know that if you use
BSD UNIX systems, you're already doing that.)  Yes, some people operating
routers will configure them to do stypid things with those values, and
some vendors will build routers that do only stupid things with those
values, but more will do far worse things, such hijacking all of your
HTTP, SMTP, or FTP packets and sending them to redirection proxies
in the name of protecting you from spam or optimizing your WWW experience.

Vernon Schryver    [email-masked]