Re: [multimob] Adoption of draft-asaeda-multimob-igmp-mld-optimization-05 as a wg document

Dear all,

I am sorry for not commenting earlier on this draft. I would like to share with all folks some comments that I have already sent to the authors.

I endorse the proposal and I do support it. However, I have some comments on the draft. Overall, there is still a need to clarify and to distinguish between two aspects in the operation of IGMP/MLD. A clear distinction between Router Operation and Host Operation should be discussed especially when it comes to tuning decision either to speed up or to slow down control signalling messages.

Another point that the authors have probably "missed" to discuss is the case where a Mobility Agent (Home Agent, Proxy or Anchor Point) is a Querier. In this case, the agent has to run multiple instances of the IGMP/MLD processes on physical network interfaces and on tunnel interfaces. The behaviour of IGMP/MLD should be naturally different as the awareness level of the multicast membership is different. In addition, the processes are not independent as one may affect the other. Fixed members may affect mobile devices that are away due to their join/leave activities.  

As the values of the different timers are concerned, I think there is no need to fix them. Authors have justified their choice based on analysis that they have done, but I think there should be a sort of variation (range that can be enlarged or shortened) depending on different circumstances and the layer 2 technology used.

Having a track record of mobile members may be easy to detect and maintain if the Home Agent is a Querier. In other cases, I don't see who we can distinguish the origin of an IGMP/MLD report message (i.e. coming from a mobile or stationary device). Routers are connected in general to Wireless Domain Systems or Access Points and they are not directly connected to mobile devices (design assumption and management issue).

Finally, a mobile device may need to speed up sending his IGMP/MLD report. As far as I know, in Mobile IP specification, a mobile device needs to wait first the reception of an IGMP/MLD query before being eligible to send a report (through the bidirectional tunnel), probably this is an implicit part of the Return Routability procedure (CoA needs to be validated before use).

Hope my comments help to improve the draft.

Kind Regards,
Imed
---------------------------------------------------
Imed Romdhani, PhD
IEEE Member, FHEA 
Lecturer in Networking
Room C 64
Edinburgh Napier University
School of Computing
10 Colinton Road
Edinburgh, EH10 5DT
UK
E-Mail:   I.Romdhani@napier.ac.uk
Home Page: http://www.dcs.napier.ac.uk/~cs244/
Telephone: +44(0)131 455 2726
Fax: +44(0)131 455 2727
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-----Original Message-----
From: multimob-bounces@ietf.org [mailto:multimob-bounces@ietf.org] On Behalf Of Stig Venaas
Sent: 26 May 2011 20:14
To: multimob@ietf.org
Subject: Re: [multimob] Adoption of draft-asaeda-multimob-igmp-mld-optimization-05 as a wg document

It looks like we have sufficient support to adopt this. Quite a few in
favor and no one against.

Hitoshi, please resubmit as a wg document,

Stig

On 5/5/2011 12:50 PM, Stig Venaas wrote:
> Hi
>
> The draft draft-asaeda-multimob-igmp-mld-optimization-05 was presented
> in the wg meeting in Prague. We were asking about adoption there. A few
> people supported it, none were against.
>
> To decide whether to adopt, we also need to check on the list.
>
> Please read the document, and state whether you think it is ready for
> adoption or not.
>
> Note that we have in our charter to submit a document on how to tune
> IGMPv3/MLDv2 for mobility.
>
> Stig
> _______________________________________________
> multimob mailing list
> multimob@ietf.org
> https://www.ietf.org/mailman/listinfo/multimob

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