Re: Multicast PS to requirements

Thanks Sergio, Seil,

Just a final comment. For PS1, not sure if the word "especially" in the sentence "The problem is especially manifested ..." should be removed.

Regards,

Luis

De: [email protected] [mailto:[email protected]] En nombre de Sérgio Figueiredo
Enviado el: miércoles, 21 de noviembre de 2012 0:21
Para: [email protected]
Asunto: Re: [DMM] Multicast PS to requirements

Hi Luis,

A few more comments on this inline:

Em 20-11-2012 19:46, LUIS MIGUEL CONTRERAS MURILLO escreveu:
Hi Anthony,

some comments in line

Best regards,

Luis

De: [email protected]<mailto:[email protected]> [mailto:[email protected]] En nombre de h chan
Enviado el: martes, 20 de noviembre de 2012 18:51
Para: Sérgio Figueiredo; [email protected]<mailto:[email protected]>
Asunto: [DMM] Multicast PS to requirements

Let us also use another thread to check for consensus of the PS from multimob.

PS1 (revised): Non-optimal routes

Routing via a centralized anchor often results in a longer route. The problem is especially manifested when accessing a local server or servers of a Content Delivery Network (CDN), or when receiving / sending IP multicast packets.

[Luis>>] This is correct if the multicast content is locally available. However this could not be always the case for multicast listeners, for a number of reasons (for instance, conflict in the multicast address allocation between the Home Network and the DMM domain).
[SF] Sure, and the same applies to "accessing a local server a CDN" - it is implicit that the content is locally available. But it can be improved as "when receiving locally available IP multicast or sending IP multicast".


PS6: Duplicate multicast traffic
IP multicast distribution over architectures using IP mobility solutions  may lead to convergence of duplicated multicast subscriptions towards the tunnel's downstream entity (e.g. MAG in PMIPv6).  Concretely, when multicast subscription for individual mobile nodes is coupled with mobility tunnels, duplicate multicast subscription(s) is prone to be received through different upstream paths. This problem is potentially more severe in a distributed mobility environment [draft-sfigueiredo-multimob-use-case-dmm-03].

[Luis>>] This seems not to be a problem of the IP mobility solutions handling multicast traffic with mobility tunnels in general, but a problem of considering several upstream paths ending on the same mobility access router as a consequence of extending tunnels from previousMAR to newMAR to forward the multicast traffic.
[SF] Exactly. Which is more than likely to happen in a DMM solution, where all "mobility entities" may act as "mobility access routers", and, after mobility, we want to take advantage of the tunnel for the subscription. In those cases, care must be taken in order to not greatly magnify convergence problem observed e.g. in RFC6224.

Regards,
Sérgio



H Anthony Chan

From: [email protected]<mailto:[email protected]> [mailto:[email protected]] On Behalf Of Sérgio Figueiredo
Sent: Monday, November 19, 2012 5:24 PM
To: [email protected]<mailto:[email protected]>
Subject: Re: [DMM] Multicast requirements

Hi Anthony,

Thank you for trying to progress on this matter. I mostly agree with your analysis.

As for the question you posed, first I would like to exactly understand what you mean with "multicast distribution scenario" in "DMM solutions should enable multicast services which are compatible with multicast distribution scenario, etc.". It seems like there is no major difference between this and the "DMM solutions should enable solutions to support multicast services." requirement? Aren't both expressing the need to enable multicast in a DMM solution?

As you stated, "neglecting" the requirement 7.1 we proposed, leads to the PSs you referred.  So, while 7.2 and 7.3 express the need for DMM solutions to allow deployment of multicast services, 7.1 concerns  "how" IP multicast should be enabled in order to avoid the aforementioned PSs. The usage of the word "flexible"is explained by:

"This flexibility enables different IP multicast flows with respect to a mobile host to be managed (e.g., subscribed, received and/or transmitted) using multiple endpoints".

In other words, compatibility with "multicast distribution scenario" doesn't necessarily avoid PS1 and PS6.

Thank you and best regards,
Sérgio

On 11/19/2012 10:28 PM, h chan wrote:
There are 3 proposals for multicast requirements. Before comparing these proposals, let us understand what are the problems first. Two problem statements have been proposed:

PS1 (revised): Non-optimal routes

Routing via a centralized anchor often results in a longer route. The problem is especially manifested when accessing a local server or servers of a Content Delivery Network (CDN), or when receiving / sending IP multicast packets.
PS6: Duplicate multicast traffic
IP multicast distribution over architectures using IP mobility solutions  may lead to convergence of duplicated multicast subscriptions towards the tunnel's downstream entity (e.g. MAG in PMIPv6).  Concretely, when multicast subscription for individual mobile nodes is coupled with mobility tunnels, duplicate multicast subscription(s) is prone to be received through different upstream paths. This problem is potentially more severe in a distributed mobility environment [draft-sfigueiredo-multimob-use-case-dmm-03].

Then, let us see whether all the 3 REQ proposals have the same intention. In the following, I rephrase them to highlight their similarities.

REQ7.1: Flexible multicast distribution
DMM solutions should be compatible with flexible multicast distribution scenario. Etc.
The Motivation is to allow flexibility in (enable) multicast solutions to solve the problems PS1 and PS6 as explained in use cases already presented and discussed in multimob wg.

REQ7.2:
DMM solutions should enable solutions to support multicast traffic.

(Original wording was "The DMM (unicast) solution MUST be specified in such a way that it can be extended to also support multicast traffic." I rephrase it to highlight the similarity with the other proposals and also changed the must to should.)

REQ7.3:
DMM solutions should enable solutions to support multicast services.

Original wording was "DMM solutions should support multicast services ... etc. Given that it is the scope of multimob and not dmm wg to provide the multicast solution, I think "support" here means "enable" solutions to be developed (by multimob).

Similarity and subtle differences: Both REQ7.2 and REQ7.3 want to enable multicast services. Yet the explanation in REQ7.1 seems to indicate not just to enable any one multicast solution but also needs the flexibility in multicast solution. Not all multicast solutions are the same. Some of them results in PS1 or PS6.

Are there any are essential differences between:
In REQ7.1, DMM solutions should be compatible with flexible multicast distribution scenario, etc.
Versus
DMM solutions should enable multicast services which are compatible with multicast distribution scenario, etc.

H Anthony Chan

From: [email protected]<mailto:[email protected]> [mailto:[email protected]] On Behalf Of Seil Jeon
Sent: Monday, November 19, 2012 5:15 AM
To: [email protected]<mailto:[email protected]>
Cc: [email protected]<mailto:[email protected]>
Subject: Re: [DMM] Multicast requirements

Hi Pierrick,

I've many times thought about your question. I would say how effectively should we deploy/support multicast over distributed mobility rather than distributed mobile multicast. As a result, you can find this deployment use case and gap analysis at http://tools.ietf.org/html/draft-sfigueiredo-multimob-use-case-dmm-03 presented in multimob several times.

In unicast DMM, main innovation is to distribute the anchor function at many access routers from single core. Following architectural concept of DMM, flexible multicast distribution is one of multicast requirement resulted from the draft described above.


REQ8: Flexible multicast distribution
"DMM solutions SHOULD be compatible with flexible multicast distribution scenarios. This flexibility enables different IP multicast flows with respect to a mobile host to be managed (e.g., subscribed, received and/or transmitted) using multiple endpoints".

Motivation: The motivation for this requirement is to enable flexibility in multicast distribution. The multicast solution may therefore avoid having multicast-capable access routers being restricted to manage all IP multicast traffic relative to a host via a single endpoint (e.g. regular or tunnel interface), which would lead to the problems described in PS1 and PS6.
PS6: Duplicate multicast traffic
IP multicast distribution over architectures using IP mobility solutions  may lead to convergence of duplicated multicast subscriptions towards the tunnel's downstream entity (e.g. MAG in PMIPv6).  Concretely, when multicast subscription for individual mobile nodes is coupled with mobility tunnels, duplicate multicast subscription(s) is prone to be received through different upstream paths. This problem is potentially more severe in a distributed mobility environment [draft-sfigueiredo-multimob-use-case-dmm-03].


Regards,

Seil

From: [email protected]<mailto:[email protected]> [mailto:[email protected]]
Sent: Monday, November 19, 2012 8:55 AM
To: '[email protected]<mailto:[email protected]>'; [email protected]<mailto:[email protected]>; [email protected]<mailto:[email protected]>
Cc: [email protected]<mailto:[email protected]>
Subject: RE: [DMM] Multicast requirements

Hi all,

I tend to agree with Georgious, however I still do not figure out what is the use-case for distributed mobile multicast (other than academic considerations)? Can someone give concrete example?

I haven't real all messages from this thread. So, maybe I missed important points.

BR,
Pierrick

De : [email protected]<mailto:[email protected]> [mailto:[email protected]] De la part de [email protected]<mailto:[email protected]>
Envoyé : samedi 17 novembre 2012 13:01
À : [email protected]<mailto:[email protected]>; [email protected]<mailto:[email protected]>
Cc : [email protected]<mailto:[email protected]>
Objet : Re: [DMM] Multicast requirements


Hi all,



I also agree that the DMM solution should somehow consider muticast deployment. However, I do not thnk that the DMM WG is the right WG to provide the multicast based DMM solution!



One alternative solution will be to have a multicast requirement that emphasizes the need of having extensibility hooks (possibilities) that can be used later on by the multimob WG to provide a

a multicast enabled DMM solution!





So a requirement that specifies something like the following could be used for this purpose:



"The DMM (unicast) solution MUST be specified in such a way that it can be extended to also support multicast traffic."





Best regards,

Georgios







________________________________
Van: [email protected]<mailto:[email protected]> [[email protected]<mailto:[email protected]>] namens Seil Jeon [[email protected]<mailto:[email protected]>]
Verzonden: vrijdag 16 november 2012 22:25
To: 'Zuniga, Juan Carlos'
Cc: [email protected]<mailto:[email protected]>
Onderwerp: Re: [DMM] Multicast requirements
Hi Juan,

I've been looked at changed flow of your proposed text but sorry now that my
comment is posted.
At first time, I couldn't make sure however, on hearing Stig's description,
it seems quite reasonable at the first step, not giving any restrictions but
leaving some-specific for the DMM solution it does not support multicast.

On the other hand, it remains at a basic stage for the DMM solution to
support multicast.
So I think additional requirements need to be made for the DMM solution,
accordingly. But of course, this should not also give any specific
limitation and restriction but should be made towards the direction not
limiting the benefits provided by distributed deployment.

I hope to get more comments on this.

Regards,

Seil


-----Original Message-----
From: [email protected]<mailto:[email protected]> [mailto:[email protected]] On Behalf Of
Zuniga, Juan Carlos
Sent: Friday, November 16, 2012 8:14 PM
To: Stig Venaas; [email protected]<mailto:[email protected]>
Subject: Re: [DMM] Multicast requirements


> -----Original Message-----
> From: Stig Venaas [mailto:[email protected]]
> Sent: Friday, November 16, 2012 3:01 PM
> To: jouni korhonen
> Cc: [email protected]<mailto:[email protected]>; Zuniga, Juan Carlos; Konstantinos Pentikousis;
> Peter McCann; [email protected]<mailto:[email protected]>
> Subject: Re: [DMM] Multicast requirements
>
> On 11/15/2012 3:17 AM, jouni korhonen wrote:
> >
> > On Nov 15, 2012, at 1:03 AM, Behcet Sarikaya wrote:
> >
> >>
> >> I think we are reading too much into multicast and unicast should
be
> >> designed in an integrated manner.
> >>
> >> The fact is that multicast is considered as an area of
> specialization,
> >> it requires knowledge of very different protocols than we are
> >> accustomed to in mobility.
> >
> > "Requirement: DMM solutions SHOULD support multicast services. If a
> specific DMM solution does not support multicast services, an
> explanation MUST be provided."
>
> This sounds good to me.
>
> The main thing I want to achieve is what was describes as motivation
> earlier in this thread. Multicast should at least be considered when
> looking into DMM solutions, and not just an afterthought once the
> solution is decided.
>
> Stig

[JCZ] I fully agree with this. That was the intention of the proposed text.

Regards,

Juan Carlos

>
> > To me that reads basically "do not break foundations for multicast
> unless you have a valid & documented reason for it".  If we look e.g.
> into RFC625 multicast wording that is there very briefly but gives a
> hint to a developer where to head to. That is the level I would expect
> DMM documents should aim to.
> >
> > - Jouni
> >
> >
> >> Let dmm deal with its current charter that does not include a word
> of
> >> multicast and if everything goes well we can come back and discuss
> dmm
> >> multicast.
> >>
> >> Regards,
> >>
> >> Behcet

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