Subject: Re: Allowing IP addresses as path-identiites

From: John Stanley <[email-masked]>
Date: Thu, 8 Sep 2005 11:01:20 -0700 (PDT)

"Charles Lindsey" <chl@xxxxxxxxxxxxxxxx>:

>No, the idea is that the syntax will be so written that IP addresses are
>not allowed in <path-identity>s, but will be allowed in
><diagnostic-identity>s (or whatever we choose to call them).

Having just been told that I was being an obstructionist for not 
discussing the "one document" that we  are supposed to discuss when I 
responded to one of Charles's proposed texts for USAGE, I'll be happy to 
point out that USEPRO does not contain syntax for the path header. That's 
in USEFOR, and USEFOR contains no such "diagnostic-identity" definition. 

Adding that syntax to that draft would be silly, since there is no real 
difference between a "path-identity" and a "diagnostic-thingy".

If we cannot allow IPv6 address literals as path-identities because they
would confuse existing software into thinking there were multiple
non-unique path-identities (the "dead:beef" problem), then they cannot be
allowed as "diagnostic-thingys" in the same header field for the very same
reason.

If we solve the dead:beef problem (I mean, use the solution already 
proposed), then we might as well allow them as path-identities. And stop 
wasting the time debating what a "diagnotic thingy" is and how to 
differentiate it and what to do when someone violates the rules.

---

From: "Charles Lindsey" <[email-masked]>
Date: Fri, 9 Sep 2005 13:53:45 GMT

>difference between a "path-identity" and a "diagnostic-thingy".

The intention AIUI is to put this restriction, presumably as syntax, in
USEFOR. There may well be a syntactic difference between a "path-identity"
and a "diagnostic-thingy" (both Forrest and I have suggested that).

>allowed as "diagnostic-thingys" in the same header field for the very same

Yes I agree with you entirely, for once, but we seem to be the only two
taking that position so far.

>proposed),

The dead:beef problem has been much over-hyped; I don't think it is a show
stopper (though if you suddenly wanted to allow ':'s in <bareword>s it
might become one). So long as we can tell people to avoid <bareword>s
consisting of hexadecimal digits only, it need not be an issue.

-- 
Charles H. Lindsey ---------At Home, doing my own thing------------------------
Tel: +44 161 436 6131 Fax: +44 161 436 6133   Web: http://www.cs.man.ac.uk/~chl
Email: [email-masked]      Snail: 5 Clerewood Ave, CHEADLE, SK8 3JU, U.K.
PGP: 2C15F1A9      Fingerprint: 73 6D C2 51 93 A0 01 E7 65 E8 64 7E 14 A4 AB A5