Subject: RE: Some comments to the draft-ietf-pilc-error-00.txt

From: Lloyd Wood <[email-masked]>
Date: Wed, 23 Jun 1999 19:16:14 +0100 (BST)

On Wed, 23 Jun 1999, Nitin Vaidya wrote:

>       > From: Lloyd Wood [mailto:[email-masked]]
>       ...
>       > What may be appropriate for a single link for 
>       > communication between
>       > its two dumb endpoints in isolation can be extremely 
>       > inappropriate for
>       > an internetwork or higher layers utilising that link, where
>       > the functionality is duplicated.
> 
> To belabor the point ...
> 
> I agree that ARQ "can" be inappropriate (as you state above), but it
> is also important to note that it is *not always* inappropriate.

Feel free to cite real examples where local ARQ is appropriate to use
in a TCP/IP internetwork, then, and not clearly bettered by
alternatives. ARQ is generally introduced by people who don't
appreciate the benefits of appropriate coding but think their link has
to have something to make it Look Good.

>       > A PILC-generated draft explaining why ARQ is bad would
>       > IMO be a laudable goal. The current errors draft doesn't discuss
>       > FEC or ARQ at all, and:
> 
> A draft looking at FEC and ARQ is a good idea,

yes.

> however, starting with
> the presumption that "ARQ is bad" is a bad idea 

Well, it's an entirely correct application of ramifications of the
end-to-end principle. "ARQ is bad" is Blindingly Obvious as the
conclusion to be reached, given interactions with TCP/IP illustrated
by Perry's example etc.

> - a more balanced draft
> will be more useful. Local FEC, local ARQ, end-to-end ARQ (and, for that
> matter, end-to-end FEC) are all useful techniques. Needless to say,
> not every technique is applicable in all situations.

end-to-end ARQ? end-to-end FEC?

Reality check, please. I can't think of a single case *in a TCP/IP
internetwork* where use of these would be at all appropriate, and I
can't see the draft covering other situations.

L.

> Enough said.
> 
> - nitin
> 
> Disclaimer: Speaking for myself ...

<[email-masked]>PGP<http://www.ee.surrey.ac.uk/Personal/L.Wood/>

---

From: Nitin Vaidya <[email-masked]>
Date: Wed, 23 Jun 1999 10:55:06 -0700

> -----Original Message-----
      ...

To belabor the point ...

      > IMO be a laudable goal. The current errors draft doesn't discuss

A draft looking at FEC and ARQ is a good idea, however, starting with
the presumption that "ARQ is bad" is a bad idea - a more balanced draft
will be more useful. Local FEC, local ARQ, end-to-end ARQ (and, for that
matter, end-to-end FEC) are all useful techniques. Needless to say,
not every technique is applicable in all situations.

Enough said.

- nitin