Re: [rtcweb] Working Group Last Call: draft-ietf-rtcweb-jsep-19.txt

Eric Rescorla <ekr@rtfm.com> Fri, 24 March 2017 15:18 UTC

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From: Eric Rescorla <ekr@rtfm.com>
Date: Fri, 24 Mar 2017 08:17:22 -0700
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To: Magnus Westerlund <magnus.westerlund@ericsson.com>
Cc: Ted Hardie <ted.ietf@gmail.com>, "rtcweb@ietf.org" <rtcweb@ietf.org>, Sean Turner <sean@sn3rd.com>, Cullen Jennings <fluffy@cisco.com>
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Subject: Re: [rtcweb] Working Group Last Call: draft-ietf-rtcweb-jsep-19.txt
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On Fri, Mar 24, 2017 at 6:23 AM, Magnus Westerlund <
magnus.westerlund@ericsson.com> wrote:

> Hi,
>
> I have reviewed the changes in the JSEP-19 document. For Appendix B see
> separate email.
>
> 1. The deleting of the "implementation requirements" (previously in 5.1.1)
> makes me wonder if the "usage requirements" and specifically the bullets in
> the current 5.1.1 is actually needed. What I can see this is a 2119
> normative rehashing of requirements that already exist elsewhere in the
> RTCWeb document suite.
>
>    All session descriptions handled by JSEP implementations, both local
>    and remote, MUST indicate support for the following specifications.
>    If any of these are absent, this omission MUST be treated as an
>    error.
>
> The above actually make some sense to ensure that these features are
> negotiated.
>
>
>    o  ICE, as specified in [RFC5245], MUST be used.  Note that the
>       remote endpoint may use a Lite implementation; implementations
>       MUST properly handle remote endpoints which do ICE-Lite.
>
> Transport specification does not mandate use of ICE, only support. But,
> the MUST be used in this paragraph, appears to be unnecessary. This due the
> above paragraph. Which results in either a received offer indicates ICE or
> one rejects it, and one must include it in those one offers. Which will
> result in usage.
>
> But, I don't think it actually is JSEP's role to mandate use of other than
> how the "signalling" element in the API surface is to be treated.
>
>
>    o  DTLS [RFC6347] or DTLS-SRTP [RFC5763], MUST be used, as
>       appropriate for the media type, as specified in
>       [I-D.ietf-rtcweb-security-arch]
>
> This is also double specification in the "MUST be used" as that is clear
> from the sec-arch document in section 5.5. that it must be used.
>
>
>    The SDES SRTP keying mechanism from [RFC4568] MUST NOT be used, as
>    discussed in [I-D.ietf-rtcweb-security-arch].
>
> Also covered in Section 5.5. of Sec-ARCH.
>
>
>
> 2. Section 5.1.2:
>
>    o  The profile in any "m=" line in any answer MUST exactly match the
>       profile provided in the offer.
>
>    o  Any profile matching the following patterns MUST be accepted:
>       "RTP/[S]AVP[F]" and "(UDP/TCP)/TLS/RTP/SAVP[F]"
>
> These two are in conflict in cases when the answer to an
> "UDP/TLS/RTP/SAVPF" offer comes back as UDP/TLS/RTP/SAVP. Then the first
> can't be fulfilled, but the second is. Isn't the rule "It either is an
> exact match or matches the following patterns"?
>

They are not in conflict. The first is about what you send. The second is
about what you accept.

-Ekr




>
>
> Cheers
>
> Magnus Westerlund
>
> ----------------------------------------------------------------------
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