Re: [rtcweb] Review comments on draft-ietf-rtcweb-data-protocol-03

Paul Kyzivat <> Wed, 05 March 2014 19:49 UTC

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Date: Wed, 05 Mar 2014 19:47:04 +0000
From: Paul Kyzivat <>
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Subject: Re: [rtcweb] Review comments on draft-ietf-rtcweb-data-protocol-03
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On 3/4/14 7:24 PM, Makaraju, Maridi Raju (Raju) wrote:
>>>> 2. Section 4:
>>>> The method
>>>>     used to determine which side uses odd or even is based on the
>>>>     underlying DTLS connection role when used in WebRTC, with the side
>>>>     acting as the DTLS client using even stream identifiers.
>>>> Isn't this unnecessary using the vague word of WebRTC instead of simply
>>>> pointing to the DTLS roles of the established data channel?
>>> The point is that in the WebRTC you use DCEP/SCTP/DTLS/UDP and therefore
>>> you can refer to the DTLS role. However, you could use DCEP/SCTP/IP
>>> or DCEP/SCTP/UDP/IP or DCEP/SCTP over something not involving DTLS.
>>> In that case DTLS is not used and you can not refer to the DTLS role.
>>> That is why the restriction is used.
>> So data channels could work over SCTP/IP or SCTP/UDP/IP, but in fact
>> can't solely because the choice of even/odd role is dependent on DTLS
>> connection role?
>> Couldn't you find a way to choose the even/odd role based solely on the
>> SCTP layer and the SDP? Then data channels could be used over those
>> other stacks.
> [Raju]
> +1
> a=setup could be used to determine this, but the final determination is done only at SDP answer (which is same for DTLS).
> For DTLS/SCTP case since both DTLS and SCTP layers use the same a=setup, both DTLS and SCTP client/servers roles match.
> So, DCEP changing text to indicate role determination be done per SCTP client/server role instead of DTLS role may just work and is compatible with existing text.
> [/Raju]