Re: Last Call: Preferred Format for Literal IPv6 Addresses in URL's to Proposed Standard

[John Stracke <[e-mail]>]

> The IESG has received a request from the IPNG Working Group to
> consider
> Preferred Format for Literal IPv6 Addresses in URL's
> <draft-ietf-ipngwg-url-literal-02.txt> as a Proposed Standard.

I believe that this format is ill-advised for two reasons.

First, it is insufficiently backwards compatible with existing
HTTP clients.  If a syntax were used that was compatible with the
existing http: syntax, then an existing client, even on an
IPv4-only machine, could pass the URL to an IPv6-enabled proxy to
contact an IPv6 server.  (For an example of such a syntax, see
draft-masinter-url-ipv6-02.txt, which suggests a pseudo-TLD
.ipv6, with rules for converting, say,
1080--8-800-200C-417A.ipv6, into 1080::8:800:200C:417A.) With
this format, however, an existing client may see the multiple
colons and decide that the URL is simply broken, and not worth
passing to the proxy.  (I previously brought this point up with
the authors of this draft; if I recall correctly, they were
simply not interested in older clients.)

Second, it uses the "[" and "]" characters, which are not legal
in URIs (see RFC-2396, Appendix A).  Section 2.4.3 of RFC-2396
lists these characters among those which were excluded because
they were "unwise"; that is, they were considered likely to be
used as delimiters in various contexts, and/or known to be
transformed by some gateways.

I hope that this format will be rejected in favor of
draft-masinter-url-ipv6-02.txt (or something like it).

--
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|John Stracke    | http://www.ecal.com |My opinions are my own.   |
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