Re: [FECFRAME-PROTO] A new informational draft on fec grouping issues

Ali,

Sorry if these comments are a little late. They are non-essential apart from
(7).

1) At the end of Section 3.1, you say the group attribute specification
'mandates us to write a=group:FEC S1 S2 R1 R1'. Actually, I think it would
be more accurate to just say that the grouping specification does not
support the case described at all.

Writing 'a=group:FEC S1 S2 R1 R1' clearly doesn't make any sense in this
case: it would be a defect in the specification if it 'mandated' something
which made no sense, whereas I think a better way to look at it is that the
specification simply doesn't address this case.

2) I'm not sure what is meant by the next sentence 'Note that source and
repair flows are identified by their payload formats and/or other
descriptors [I-D.begen-fecframe-sdp-elements].' Also, it doesn't seem
relevant in this context where we describe limitations of the other
specifications.

3) 3.3. - the requirement to obey the prioritisation is a SHOULD in this
context, since it is just an optimisation.

4) 3.3 - 'It might be highly desirable to keep all the receivers ...' -
'all' should be 'most'.

5) 3.3 - 'Currently, there is no SDP semantics for indicating the priority
levels of the individual flows that are grouped in an "a=group" line.' -
remove from 'that are grouped ...' onwards, since we have not decided to use
the a=group and indeed are pointing out where it is deficient

6) 4 - 'There are two main solution approaches.' - That's a broad statement!
Perhaps you mean there are two solution approaches described in the draft ?
Another possibility would be to define an fec-specific mechanism, where each
repair flow simply refers directly to the protected source flows (this is
done in 3GPP, for example).

7) 4.1 and 4.2 - in the examples, the FEC repair flows should be
'application' not 'video' type and the transport identifier should be
'udp/fec', not 'rtp/avp'. There should not be an rtpmap attribute.

...Mark

On 2/13/08 7:45 AM, "Ali Begen (abegen)" <abegen@cisco.com> wrote:

> Hi Rajiv,
> 
> Thanks for reading the draft. For other who have not started reading,
> pls see the updated version (attached).
> 
> I asked someone without any FEC background to comment on the draft
> (seems that we will have the same issue in MMUSIC). So, I expanded the
> intro part and make clarifications about what we meant with
> prioritization, additivity, etc.
> 
> Thanks again,
> -acbegen
> 
>> -----Original Message-----
>> From: Rajiv Asati (rajiva)
>> Sent: Wednesday, February 13, 2008 5:36 AM
>> To: Ali Begen (abegen); 'fecframe-proto@ietf.org'
>> Subject: RE: [FECFRAME-PROTO] A new informational draft on
>> fec grouping issues
>> 
>> Hi Ali,
>> 
>> That's fine. 
>> I just got to see the draft. Looks fine to me.
>> 
>> Cheers,
>> Rajiv
>>  
>> 
>>> -----Original Message-----
>>> From: Ali Begen (abegen)
>>> Sent: Tuesday, February 12, 2008 4:28 PM
>>> To: Rajiv Asati (rajiva); 'fecframe-proto@ietf.org'
>>> Subject: RE: [FECFRAME-PROTO] A new informational draft on fec
>>> grouping issues
>>> 
>>> This is just for describing the problem and showing some
>> alternative 
>>> solutions. It does not have to become anything.
>>> That's why, it is intended to be informational.
>>> 
>>> If MMUSIC agrees to adopt one of the solutions described
>> here or comes 
>>> up with a new one, then of course we should work on that draft
>>> together, which should be in the cateogry of "proposed standard."
>>> 
>>> However, note that MMUSIC WG should approve what needs to be done
>>> here. And, that's why we need to tell them about our problems.
>>> 
>>> -acbegen
>>> 
>>>> -----Original Message-----
>>>> From: Rajiv Asati (rajiva)
>>>> Sent: Tuesday, February 12, 2008 1:17 PM
>>>> To: Ali Begen (abegen); fecframe-proto@ietf.org
>>>> Subject: RE: [FECFRAME-PROTO] A new informational draft on fec
>>>> grouping issues
>>>> 
>>>> Hi Ali,
>>>> 
>>>> We (the protocol team) should all collaborate to jointly
>> author the 
>>>> new draft, if/when it needs to be produced.
>>>> 
>>>> Also, why should it be the informational draft?
>>>> 
>>>> Cheers,
>>>> Rajiv
>>>> 
>>>>> -----Original Message-----
>>>>> From: fecframe-proto-bounces@ietf.org
>>>>> [mailto:fecframe-proto-bounces@ietf.org] On Behalf Of Ali Begen
>>>>> (abegen)
>>>>> Sent: Tuesday, February 12, 2008 4:04 PM
>>>>> To: fecframe-proto@ietf.org
>>>>> Subject: [FECFRAME-PROTO] A new informational draft on
>>> fec grouping
>>>>> issues
>>>>> 
>>>>> Hi everyone,
>>>>> 
>>>>> So far, we could not ignite a discussion in the MMUSIC WG
>>> regarding
>>>>> the FEC grouping issues. So, it was suggested that I
>>> would write an
>>>>> informational draft, describe the problems and propose some
>>>>> alternative solutions. So, that is what I did.
>>>>> 
>>>>> I am attaching the draft for your review. Note that this
>>> has to be
>>>>> submitted by Monday. So any comments within this week
>>>> (before Friday)
>>>>> would be appreciated. It is important that we convey our issues
>>>>> appropriately. So, please take a few minutes to review the
>>>> document. 
>>>>> It is very short, and should not take much time.
>>>>> 
>>>>> Thanks,
>>>>> -acbegen
>>>>> 
>>>> 
>>> 
>> 
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