Subject: Re: [sipcore] Using an INFO package in draft-ietf-ecrit-ecall-11 - Christer's compromise proposal

From: Christer Holmberg <[email-masked]>
Date: Fri, 2 Sep 2016 07:23:26 +0000

Hi Roland,

I think everyone agrees that MSD can be sent in the initial INVITE.

The question was whether we should allow MSD to be sent in mid-call
UPDATEs, or whether one always has to use INFO. Personally I think one
should only use INFO mid-call. UPDATEs are not meant to transport
application information, and I believe the processing of UPDATEs also
consume more resources than INFOs, since you have to check how/if the
UPDATE affects the SIP state etc.

Regards,

Christer

On 01/09/16 23:06, "[email-masked]" <[email-masked]> wrote:

>Hi Christer,
>
>>...or, in draft-ecrit-ecall we can say that MSD can only be sent in the
>>initial INVITE and INFOs.
>
>That I would prefer, because I assume that we will have a lot of calls
>where we even do not need any additional MSD send in the midcall (i.e.
>INFO). 
>
>So I would save an additional roundtrip in SIP to get the information.
>
>Best regards
>
>Roland
>
>-----Ursprüngliche Nachricht-----
>Von: sipcore [mailto:[email-masked]] Im Auftrag von Christer
>Holmberg
>Gesendet: Donnerstag, 1. September 2016 21:15
>An: Paul Kyzivat; [email-masked]
>Betreff: Re: [sipcore] Using an INFO package in draft-ietf-ecrit-ecall-11
>- Christer's compromise proposal
>
>Hi,
>
>...
>
>>> I would actually support MUST use INFO, unless you happen to send
>>> UPDATE for some other purpose. I don't want people to start using
>>> UPDATE instead of INFO, because that's not proper SIP, in my opinion.
>>>MSD is application information, and doesn't impact the SIP session
>>>state, so INFO shall be used.
>>>
>>> If someone wants to forbid usage of UPDATE for transporting MSD in
>>> *any* circumstance, and only allow INFO mid-session, I probably would
>>> not object to that either :)
>>
>> I guess you can forbid this usage for MSD if you wish, as part of the
>>definition of MSD.
>
>...or, in draft-ecrit-ecall we can say that MSD can only be sent in the
>initial INVITE and INFOs.
>
>Also, the rate of INFOs can be "controlled" within the info package
>specification, but there is nowhere to do it for UPDATE. So, the more I
>think about it, there more I think we should NOT allow MSD in UPDATE. I
>don't really see a need for it, as MSD is not expected to be sent too
>often to begin with.
>
>An UPDATE can of course be used to re-negotiate the supported info
>packages, but that's a separate thing (which I don't think is needed for
>ecall).
>
>Regards,
>
>Christer
>
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