Subject: [Monami6] Comments on draft-montavont-monami6-multihoming-pb-statement

From: Romain KUNTZ <[email-masked]>
Date: Fri, 28 Oct 2005 17:26:27 +0900

Dear authors,

I have some comments regarding
draft-montavont-monami6-multihoming-pb-statement-05

> 5.1. (1,1): 1 HoA, 1 CoA

You state that
> There cannot be more than two interfaces, otherwise the mobile node 
> would either have (A) multiple interfaces on the home link, or (B) 
> multiple interfaces on foreign links. For (A), there would be 
> multiple HoAs. For (B) there would be multiple CoAs.

Actually the node can have more than 2 interfaces, but not all used at
the same time (eg: one on HL, several on Foreign Links used
sequentially). It could be useful to precise "There cannot be more than
two interfaces used simultaneously".

> 6.2.2. Using one HoA as a CoA

I am not sure about the circular references in that case. you say:

> MN has two HoAs (HoA1 and HoA2) on two distinct home links. MN is
> connected to these two home links via two interfaces.

If you have two Home links, you also have 2 different HA in each you
register one HoA. So if you register HoA2 as a CoA for HoA1 in HA1, I am
not sure a circular reference can happen, because HoA2 is not registered
  as a HoA in HA1 (it is registered as a HoA in HA2).

Regards,

-- 
Romain KUNTZ
[email-masked]

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---

From: Nicolas Montavont <[email-masked]>
Date: Fri, 28 Oct 2005 16:43:54 +0000

Romain,

> two interfaces used simultaneously".

You are right, but we thougth to that implicitly: especially in the 
scenario section, we only talk about available interfaces, which means 
interfaces that can be used simultaneously. Of course, you can always 
have other interfaces that are shutdown or not connected to a point of 
attachment. It is not important to consider those in the description.

Do you think we should clarify this?

>  as a HoA in HA1 (it is registered as a HoA in HA2).

Ok we tried to say two different things here:  first we need to be able 
to register a HoA as a CoA with another HoA. I think you have no pb with 
that.

About the example, I think you are right. I don't find anymore the show 
case which is described in the draft by

New BU: HoA = addr1 w/ CoA = addr2
existing entries:HoA = addr2 w/ CoA = addr3
     		 HoA = addr3 w/ CoA = addr1

But what we wanted to say, is that when you have 2 HoAs, it should not 
cause any problem to register one of them as a CoA for the other. You 
just have to take care that you don't have this:
    HoA1 <-> HoA2
    HoA2 <-> HoA1
in any binding cache (HA or CN)

I'll revise this section. Thanks for pointing out.

Nicolas

---

From: Romain KUNTZ <[email-masked]>
Date: Tue, 01 Nov 2005 00:40:46 +0900

Hi Nicolas,

Nicolas Montavont wrote:
>> Actually the node can have more than 2 interfaces, but not all used
>> at the same time (eg: one on HL, several on Foreign Links used 
>> sequentially). It could be useful to precise "There cannot be more
>> than two interfaces used simultaneously".
> 
> 
> scenario section, we only talk about available interfaces, which
> means interfaces that can be used simultaneously. Of course, you can
> always have other interfaces that are shutdown or not connected to a
> point of attachment. It is not important to consider those in the
> description.
> 

As long as it is clarified in the scenario section, I think it is
enough. I did not pay attention to that, sorry.

>> If you have two Home links, you also have 2 different HA in each
>> you register one HoA. So if you register HoA2 as a CoA for HoA1 in
>> HA1, I am not sure a circular reference can happen, because HoA2 is
>> not registered as a HoA in HA1 (it is registered as a HoA in HA2).
> 
> 
> Ok we tried to say two different things here:  first we need to be
> able to register a HoA as a CoA with another HoA. I think you have no
> pb with that.

No problem with that. But IMHO the example chosen could be better:

> As an example, a MN has two HoAs (HoA1 and HoA2) on two distinct home
> links. MN is connected to these two home links via two interfaces. If
> the MN looses its connectivity on its first interface, HoA1 is not
> reachable. It may then want to register HoA2 as a CoA for HoA1 in
> order to keep receiving packets intended to HoA1, via the second
> interface.

The example you give is very specific (MN is connected on the home links
on its both interfaces). Actually I think the following example may be
more relevant: the MN has 2 interfaces, and 2 HoAs (HoA1 and HoA2).
Both interfaces are connected to a foreign network, thus you have 2
CoAs, each one binded to one HoA (say CoA1 to HoA1, and CoA2 to HoA2).
If one interface fails, for example the one with CoA1, then the MN could
register HoA2 as another CoA for HoA1. This is basically what is
explained in draft-you-monimi6-management-using-hoa-coa-00.txt

> About the example, I think you are right. I don't find anymore the
> show case which is described in the draft by
> 
> New BU: HoA = addr1 w/ CoA = addr2 existing entries:HoA = addr2 w/
> CoA = addr3 HoA = addr3 w/ CoA = addr1
>  
> But what we wanted to say, is that when you have 2 HoAs, it should
> not cause any problem to register one of them as a CoA for the other.
> You just have to take care that you don't have this: HoA1 <-> HoA2 
> HoA2 <-> HoA1 in any binding cache (HA or CN)

Actually I don't think it can happen on the HA, but this may happen on
the CN, so the example is still relevant, at least for the CN side.

Regards,

Romain