Subject: RE: [nemo] FW: Multiple DRs on a link

From: "Pascal Thubert \(pthubert\)" <[email-masked]>
Date: Wed, 17 Mar 2004 13:48:12 -0000

> -----Original Message-----
> From: Soliman Hesham [mailto:[email-masked]]
> Sent: mercredi 17 mars 2004 13:51
> To: Pascal Thubert (pthubert); IETF NEMO WG
> Subject: RE: [nemo] FW: Multiple DRs on a link
> 
> 
> 
>  > > => Hmm, that's interesting. I must have missed that in the
>  > > spec. So, my concern is similar to yours, how does the HA
>  > > check whether the MRs are in the same place?? Seems like
>  > > a dangerous feature to have. I'm surprised this wasn't discussed
>  > > during LC.
>  > >
>  > Well, Nemo requires that some authorization be run, that's
>  > not described
>  > in the spec. Such a test could take place there, or the
authorization
>  > could bar a second registration for a same prefix, I guess.
> 
> => That seems too handwavy for a standards track doc. What
> is the point of having the same prefix for more than one MR
> anyway? Is it a quick fix for multihoming ? I'm not sure
> that this is even true because even the MR might not always
> know if it should send a BU or not for its own prefix.
> 
> Perhaps this (I'm reluctant to call it feature)
> capability should be removed and only have 1 prefix per MR.

I'm not sure it's a quick fix. But it's an opening for sure. Multihoming
will have a harder time if we bar that situation blindly. In fact, the
Nemo spec is very open to future add-ons, and was wanted that way.

Taking the train case, I see it as a value to be able to configure the 2
MRs with the same mobile prefix. If the configuration is controlled
properly then that's no problem. Seems nicer to me to probe for error as
opposed to forbid...

Now, whether you support this configuration or not, you may want to
check for it anyway. DAD is not wanted in MIP but it's checked for. 

And if the check is added and finds that the situation is OK, why bar
it?

Pascal

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From: Thierry Ernst <[email-masked]>
Date: Thu, 18 Mar 2004 11:48:44 +0900

Dear all,

This is a good item for the multihoming problem statement document. 

Back to the point, this probably requires a delegation mechanism between
the 2 MRs, this could be explained in a separate document, but
dis-allowing it in NEMO Basic Support would break the spirit of 

R12: The solution MUST function for multihomed MR and multihomed
        mobile networks as defined in [NEMO-TERMS]).

draft-ietf-nemo-requirements-02.txt

So, I'm against removing this capability (several MRs on the link) and
the like.

What the NEMO Basic Support specification should say is that
configuration other than one single mobile subnet (i.e. not multihomed
or nested) or not guaranteed to work properly without additional
mechanisms.

Thierry.

---

From: Thierry Ernst <[email-masked]>
Date: Thu, 18 Mar 2004 11:48:44 +0900

Dear all,

Thierry.