I agree with Rockson.
As far as inferring somebody that doesn't understand this at all, if you
offer a=sendonly, recvonly, or inactive, and get no complementary a= in
the response you can presume the answerer didn't understand, so that you
are still sendrecv. But I don't think you infer anything from the
absence of a=sendonly in an answer to an offer with a=sendrecv.
Paul
Rockson Li (zhengyli) wrote:
> Alex,
>
> I think a=sendrecv should be assume if no direction attribute specified.
>
> As per RFC4566,sec 6
>
> a=sendrecv
>
> ...
> If none of the attributes "sendonly", "recvonly", "inactive",
> and "sendrecv" is present, "sendrecv" SHOULD be assumed as the
> default for sessions that are not of the conference type
> "broadcast" or "H332" (see below).
>
> And you can check the example of RFC4317 , many answer of them has no
> a=sendrecv, which is assumed.
>
> Regards,
> -Rockson
>
>
>
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On Behalf Of
> [EMAIL PROTECTED]
> Sent: Friday, July 04, 2008 2:47 PM
> To: [EMAIL PROTECTED]; [email protected]
> Subject: Re: [Sip-implementors] a=sendrecv in SDP answer
>
> For UAS, whether or not the SDP offer without a=sendrecv is processed as
> sendrecv?
>
> In our UAS implementation, if the incoming non-initial SDP offer carrys
> no direction attribute, it will be regarded as no mode requirement. I
> think it is incompliant to the RFC3264.
>
>
> Alex Zhang
> ESN: 6-554-8782
>
>
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On Behalf Of
> Arun Arora
> Sent: Friday, July 04, 2008 12:29 PM
> To: [email protected]
> Subject: Re: [Sip-implementors] a=sendrecv in SDP answer
>
> No, it can't be done this way. By adding a=sendrerv we are clearly
> distinguishing b/w RFC 2543 and RFC 3261. So, For an "a=sendrecv" there
> has to be an "a" attribute in the answer.
>
> Arun
>
> --- On Fri, 4/7/08, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
> From: [EMAIL PROTECTED] <[EMAIL PROTECTED]>
> Subject: [Sip-implementors] a=sendrecv in SDP answer
> To: [email protected]
> Date: Friday, 4 July, 2008, 7:04 AM
>
> RFC3261 - 6.1, pargraph 4:
> "If an offered media stream is
> listed as sendrecv (or if there is no direction attribute at the
> media or session level, in which case the stream is sendrecv by
> default), the corresponding stream in the answer MAY be marked as
> sendonly, recvonly, sendrecv, or inactive."
>
> My question is that: If the SDP offer contains the a=sendrecv, can the
> SDP answer omit the a= line to represent the default value, i.e:
>
> Offer (a=sendrecv) ---->
> <--- Answer(no a=sendrecv line )
>
> Thanks,
> Alex
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