Re: Terminology and scenario (wasRe: [Monami6] about draft-montavont-mobileip-multihoming-pb-statement-05current)

[Ryuji Wakikawa <[e-mail]>]

Hi Marcelo

At Fri, 22 Jul 2005 16:41:19 +0200,
marcelo bagnulo braun wrote:
> 
> > This is a very intersting distinction that we should take into 
> > account. I am thinking to multiple coas registration / flows filtering 
> > here, where only one address pair becomes unreachable  (let say CoA1 
> > <-> CN1) and not other pairs using CoA1. We need a mechanism to change 
> > the registered CoA1 with CN1, without modifying other bindings related 
> > to CoA1. This is one more reason why it would be useful to be able to 
> > independantly manage CN/flows.
> >
> 
> since you find it interesting, i will move to ascii art to put a simple 
> example of a situation where this could happen
> 
> I will only consider CoAs, now.
> Suppose that you have a given visited network, which is multihomed to 
> ISPA and ISPB, and each one of the ISPs has delegated a prefix i.e. 
> PrefA and PrefB
> 
> The MN arrives to the visited network and configures one CoA from each 
> prefix, let's say PrefA:MN and PrefB:MN
> 
> The situation then is:
> 
> 
>         +---------------------+
>         | Rest of the Internet|---------|
>         +---------------------+         |
>           |                 |          +----+
>        +-----+          +-------+      | CN2|
>        |ISPA |          | ISPB  |--|   +----+
>        +-----+          +-------+  |
>           |                 |     +----+
>         +---------------------+   | CN1| PrefB:CN1
>         | Visited Network     |   +----+
>         |    PrefA    PrefB   |
>         +---------------------+
>                 |
>              +-----+
>              |  MN | CoA1: PrefA:MN
>              +-----+ CoA2: PrefB:MN
> 
> Now consider the case where the link between ISPB and the rest of the 
> internet fails
> Which addresses does MN has to use in order to maintain a communication 
> with CN1? and with CN2?
> 
> With CN1, the only path available between CN1 and the MN is through 
> ISPB, so the MN must use PrefB:MN as CoA for this communication

I think PrefB:MN can be selected according to the same mechanism of
IPv6 source address selection. (i.e. by Address longest match).

> With CN2, the only path available between CN2 and the MN is through 
> ISPA, so the MN must use PrefA:MN as CoA for this communication

It depens on where the HA is located, but..
When the MN attempts to use PrefB:MN, it fails to send CoTI/HoTI and will
not receive CoT/HoT.  Therefore, it will give up using PrefB:MN and will
pick up PrefA:MN. right?

So is there any possible issue here?

regards,
ryuji


> (this is site multihoming example adapted to mobile host multihoming, 
> sorry for that, but there maybe better examples that express this 
> situation in a more relevant fashion for this case)
> 
> Regards, marcelo
> 
> 
> 
> 
> 
> > Nicolas
> >
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> 
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