Hi,
I think this is a good start, but I have some comments:
Media-plane stuff:
------------------
This looks rather ok, but I am not sure I understand the
retransmission issue. The CSeq will take care of that, won't
it?
Or, do you mean that retransmission can delay the
information to reach the recevier? If so, isn't it covered
with the first bullet (low latency)?
SUB-NOT vs INFO stuff:
----------------------
For INFO I think we should say that it can be used when the
data may be sent is associated to the dialog sent within,
and is sent only for the duration of that dialog (unless a
media-plane session is more appropriate for that specific
data type, of course).
For INFO I think we should also add cases when there are
dialog-path intermediates (without media access) interested
in the data.
For SUB-NOT I think we should add text about data which is
not associated to an invite dialog, or not associated to the
lifetime of an invite dialog.
I think that the current SUB-NOT bullets could be applicable
to INFO also. I don't think we can forget the multiple
dialog issue with SUB-NOT (which is one of the reasons why
people use INFO in the first place). Of course that doesn't
automatically mean that people are allowed to use INFO for
anything they could also use SUB-NOT for, but I see no
reason why INFO can't be used e.g. in cases where it is
"very likely that some data will be sent" (ISUP is
one example, where in many cases nodes will know it will be
sent).
To me one important difference between INFO and SUB-NOT is,
as described earlier, whether the data is associated with a
specific invite dialog, and whether the data will only be
sent during the lifetime of that invite dialog. If not,
SUB-NOT is better.
What do you mean by "multiplicity of events containing
that data"?
Regards,
Christer
> -----Original Message-----
> From: Jonathan Rosenberg [mailto:jdrosen cisco.com]
> Sent: 13. joulukuuta 2007 7:14
> To: IETF SIP List
> Subject: [Sip] proposed litmus tests for INFO
>
> Based on Hadriels use cases, I'd like to suggest some
litmus
> tests that one can use to help determine if something
is best
> done by INFO or something else:
>
> Cases where a media-plane session is the best
solution:
>
> * there are requirements for low latency delivery
(camera
> control for
> example)
>
> * there are requirements that the data shouldn't be
> retransmitted since latency trumps reliability
(coordinate
> updates for a pointer on a whiteboard or something like
that)
>
> * the data consists of a large number of messages
that are
> likely to be sent during the duration of the session
>
> * the data is potentially very large
>
> Cases where SUB-NOT is the best solution:
>
> * the entity that wants to receive the data knows
with
> high probability that the other side is likely to send
a
> notification with the data, and it knows specifically
what
> type of data it needs to receive
>
> * the entity that wants to receive the data is
likely to
> receive a multiplicity of events containing that data
>
> Cases where INFO is the best solution:
>
> * the recipient of the data has no idea if the
sender will
> ever generate the data; the recipient is just saying
that it
> knows how to handle it, should the sender have
something to send
>
> * the recipient could potentially handle many
different
> types of data with the above characteristic
>
> * the size of the data that is to be sent is small
and
> infrequent, at most a few times during the session
>
> * the data needs to be sent reliably and latency is
not
> much of an issue
>
> * the data has no impact on SIP dialog state,
transaction
> state, media session states or intermediate proxy or
b2bua states
>
>
> -Jonathan R.
>
> --
> Jonathan D. Rosenberg, Ph.D. 499
Thornall St.
> Cisco Fellow Edison,
NJ 08837
> Cisco, Voice Technology Group
> jdrosencisco.com
> http://www.jdrosen.net
<http://www.jdrosen.net/&g
t; PHONE: (408) 902-3084
> http://www.cisco.com
<http://www.cisco.com/>
>
>
> _______________________________________________
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> This list is for NEW development of the core SIP
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> Use sippingietf.org for new developments on the
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>
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