Subject: [SIP] SIPURL IPv6 address possibly incorrect

From: Jacobus Alberts <[email-masked]>
Date: Wed, 5 Jul 2000 12:37:27 +0200

Hello

My apologies if what I am about to raise has already been covered somewhere
else in this list, but I have briefly checked, I do not think so.

I believe that the ABNF for the IPv6Address is incorrect.  In RFC2373, an
extra element is defined as 
IPv6prefix = hexpart "/" 1*2DIGIT and then subsequently,
IPv6address = IPv6prefix [":" IPv4address]

The above definition is more sensible to me, since ":" can occur in the
hexpart.  If the definition from the RFC2543 is used, hexpart replaces
IPv6prefix above.  Then it would be impossible to distinguish between a ":"
in the hexpart or the ":" delimiting the optional IPv4address (should you
want to parse such that IPv4address could be extracted of course!)

Have I missed some comment in the RFC regarding this?  Or is the issue
raised valid?  

Jacobus Alberts

Azisa (Pty) Ltd
email: [email-masked]

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From: Henning Schulzrinne <[email-masked]>
Date: Wed, 05 Jul 2000 15:26:08 -0400

> IPv6address = IPv6prefix [":" IPv4address]

I'm not sure what edition of RFC 2373 you are reading, but mine reads in
Appendix B:

      IPv6address = hexpart [ ":" IPv4address ]
      IPv4address = 1*3DIGIT "." 1*3DIGIT "." 1*3DIGIT "." 1*3DIGIT

      IPv6prefix  = hexpart "/" 1*2DIGIT

      hexpart = hexseq | hexseq "::" [ hexseq ] | "::" [ hexseq ]
      hexseq  = hex4 *( ":" hex4)
      hex4    = 1*4HEXDIG

which is exactly what's in the SIP I-D.

> want to parse such that IPv4address could be extracted of course!)

I don't understand. IPv6prefix is not used for addresses, only for
address prefixes, such as

12AB:0:0:CD3/60 (see pg. 5 of RFC 2733)

Just like 12.1.0.0/16 would never appear in an URL, the IPv6 prefix
wouldn't either.

-- 
Henning Schulzrinne   http://www.cs.columbia.edu/~hgs