Hi Behcet,

Thanks for your comments, and sorry for the late response.

Please, find our answers in line

Best regards,

Luis

De: [email protected] [mailto:[email protected]] En nombre de 
Behcet Sarikaya
Enviado el: jueves, 31 de enero de 2013 0:28
Para: [email protected]
Asunto: [multimob] draft-ietf-multimob-handover-optimization-01

Hi Carlos, authors,

Some initial comments on your draft:
Section 4.2 states that two new flags are defined but Flag A is not used in the 
line.
[Luis>>] Actually section 4.2 covers the description of both flags, A and S. 
There is an specific section inside for any of them, being 4.2.1 devoted to 
flag S, and section 4.2.2 to flag A. We can improve the text explicitly mention 
this to help the reader.

Subscription Query/Response messages: why not use the Update Notification 
message in draft-ietf-netext-update-notifications-00?
[Luis>>] The mechanism described in draft-ietf-netext-update-notifications-00 
focus on notifications triggered by the LMA. Despite the query from LMA to pMAG 
in the proactive handover case could be seen as one potential use case, the 
scope of the Subscription Query/Response messages is wider. These messages are 
also used by the nMAG for retrieving the multicast subscription information 
from the LMA in situations where the unicast binding is allowed to progress 
till the multicast information is ready, preventing large delays of the binding 
acknowledgement for unicast traffic (see section 5.2.4). In our opinion, a 
common mechanism should be used in both cases.

Why is it necessary to define messages other than PBU/PBA from MAG to LMA, i.e. 
Act Ind?
[Luis>>] The idea behind the new messages described in the WG draft is the use 
of specific and lightweight signaling methods for handling some flags in 
support of multicast handover optimization. For instance, the multicast 
activity indication represents the change in the multicast status state ( 
subscribed / not subscribed to any group) of one interface in the MAG. Strictly 
speaking, this event is not related to the purpose of PBU/PBA signaling.

Regarding Figs 1 & 2, and also the Flag A, MLD Done is only in MLDv1 and has 
been removed from MLDv2, check Appendix B in RFC 3810.
[Luis>>] That's correct, although the parts of the text where the reference to 
the MLD Done message appear are actually on Figure 3 and the first bullet below 
that figure. Our proposal is to change the text of the figure from "MLD Done" 
to "MLD Report" for brevity, and to change the text in the bullet from "MLD 
Done" to "MLD Report message (with a filter mode change record indicating 
EXCLUDE mode for the last subscribed multicast group)".

MLD Done was mimicking IGMPv2 Leave message which is not mentioned in IPv4 
support.

The fact that MLD Done (or IGMP Leave) no longer available in SSM makes me 
question the A Flag. How could LMA sustain a valid value of the A Flag?
OTOH, A Flag is only used for optimization, as shown in Figure 6.
Would it be possible to not define A Flag and use S Flag?
[Luis>>] Flag A helps to optimize the number of messages between PMIP entities 
by limiting the interrogation of the pMAG by the LMA in the case of reactive 
handover just to the case where the MN in the handover is maintaining an active 
multicast session. The proposed solution could work without using the flag A, 
but at the cost of delivering much more signaling messages than the strictly 
needed (all the messages for the MNs without multicast session does not need 
any supporting message for multicast handover optimization).


Regards,

Behcet

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