Re: [rtcweb] Is rtcweb the right place for draft-ietf-rtcweb-mdns-ice-candidates?

Justin Uberti <> Thu, 04 July 2019 00:58 UTC

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From: Justin Uberti <>
Date: Wed, 3 Jul 2019 17:58:28 -0700
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To: Roman Shpount <>
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Subject: Re: [rtcweb] Is rtcweb the right place for draft-ietf-rtcweb-mdns-ice-candidates?
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Hmm, that's unfortunate. I think this is a mistake, given that we are about
to throw the switch to enable mDNS for 100% of Chrome endpoints; Chrome
(and soon all browsers) will have to ignore ice-sip-sdp until this
extension spec is written.

ice-sip-sdp isn't published yet, so it seems an update to that document
could still be a possibility. If that's not an option, putting forth #1 as
a specific extension that allows FQDN candidates to be generated in certain
situations seems like the right path.

On Wed, Jul 3, 2019 at 5:40 PM Roman Shpount <> wrote:

> Part of the problem is that mmusic have decided to punt on the FQDN
> support. In the current mmusic-ice-sip-sdp the final language that was
> included:
> <connection-address>:  is taken from RFC 4566 [RFC4566].  It is the IP
> address of the candidate, allowing for IPv4 addresses, IPv6 addresses, and
> fully qualified domain names (FQDNs).  When parsing this field, an agent
> can differentiate an IPv4 address and an IPv6 address by presence of a
> colon in its value - the presence of a colon indicates IPv6.  *An agent
> generating local candidates MUST NOT use FQDN addresses.  An agent
> processing remote candidates MUST ignore candidate lines that include
> candidates with FQDN *or IP address versions that are not supported or
> recognized.  *The procedures for generation and handling of FQDN
> candidates, as well as, how agents indicate support for such procedures,
> need to be specified in an extension specification.*
> So, at this point we have two options:
> 1. draft-ietf-rtcweb-mdns-ice-candidates can update ice-sip-sdp and define
> how FQDN candidates generated by mdns are handled
> 2. write a new draft in mmusic which defines FQDN handling
> In any case some sort of mmusic discussion is needed to reconcile this.
> Best Regards,
> _____________
> Roman Shpount
> On Wed, Jul 3, 2019 at 8:28 PM Justin Uberti <> wrote:
>> The problem this draft is trying to solve is fairly RTCWEB-specific. If
>> there are individual issues to resolve, we can send them out to mmusic for
>> discussion, but AFAIK no changes to existing ICE specs are needed.
>> On Wed, Jul 3, 2019 at 4:26 PM Roman Shpount <> wrote:
>>> Hi All,
>>> Is rtcweb the right place for draft-ietf-rtcweb-mdns-ice-candidates?
>>> This entire draft seems to be ICE/SDP specific and not limited to rtcweb.
>>> Also, there are significant interop implications for this draft
>>> between browser and non-browser end points which probably warrant larger
>>> discussion outside of rtcweb group. I would think mmusic would be a much
>>> better place for this draft. I know there is an incentive to complete this
>>> draft quickly but this has a potential to break a lot of things (it already
>>> did break interop with almost every existing ICE implementation).
>>> Regards,
>>> _____________
>>> Roman Shpount
>>> _______________________________________________
>>> rtcweb mailing list