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Re: [MMUSIC] Should we put the SCTP max message size in the SDP?

From: Justin Uberti <juberti@google.com>
Date: Mon, 25 Nov 2013 16:12:47 -0800
Message-ID: <CAOJ7v-3qC9xa30nChvRNqy87OpVLZ3mdWDQ0Ckf8QRW6PSALXg@mail.gmail.com>
To: Peter Thatcher <pthatcher@google.com>
Cc: Eric Rescorla <ekr@rtfm.com>, Martin Thomson <martin.thomson@gmail.com>, Michael Tuexen <Michael.Tuexen@lurchi.franken.de>, "mmusic@ietf.org" <mmusic@ietf.org>, "public-webrtc@w3.org" <public-webrtc@w3.org>
I agree with Eric's suggestions, including '0' as a special case.

Regarding naming, I kind of prefer "max-", as there is ample precedent for
this, e.g. maxptime, maxplaybackrate in
http://tools.ietf.org/html/draft-spittka-payload-rtp-opus-03. In fact, for
optimal consistency I would argue for |maxmsgsize|.

Regarding how the parameter is specified, I beg you not to use positional
arguments, and use fmtp named arguments instead, e.g.
a=sctpmap:5000 webrtc-datachannel
a=fmtp:5000 maxmsgsize=65536


On Mon, Nov 25, 2013 at 8:13 AM, Peter Thatcher <pthatcher@google.com>wrote:

> Your proposal all sounds good to me.  I don't feel strongly one way or the
> other about "max-" vs. "supported-".
>
>
> On Sun, Nov 24, 2013 at 8:15 AM, Eric Rescorla <ekr@rtfm.com> wrote:
>
>> For concreteness, here's what I suggest.
>>
>> - An SDP attribute which indicates the maximum message size that
>>   the endpoint is willing to accept. The other side should assume that
>>   any larger message will be rejected, though there is no requirement
>>   that it do so (just as there is no requirement to behave in any
>>   particular way if an unadvertised RTP PT is received).
>>
>> - If the attribute is not present, the assumption is that there is some
>>   sensible (small) default that matches the behavior of existing
>>   browsers. 64k?
>>
>> - An attribute value of '0' means I will do my best with whatever you
>>   send me, subject to memory capacity, etc.
>>
>> - Proposed name: 'max-message-size'
>>
>> -Ekr
>>
>>
>>
>> On Sat, Nov 23, 2013 at 2:54 PM, Martin Thomson <martin.thomson@gmail.com
>> > wrote:
>>
>>> On 23 November 2013 13:32, Eric Rescorla <ekr@rtfm.com> wrote:
>>> > 3. The semantics should be that each side just gets to inform the other
>>> > side of their value, not that it's negotiated.
>>>
>>> This is especially important.  "negotiation" here makes zero sense.
>>>
>>
>>
>
Received on Tuesday, 26 November 2013 00:13:51 UTC

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