Re: [DNA] Considerations for DNA Schemes with multiple Interface andLayer 2 Technologies

[JinHyeock Choi <jinchoe@samsung.com>]

Dear Pekka

> I have to admit that I am totally confused now.  Maybe I just
> don't know the facts.  So, let me ask some stupid questions:
> 
> 1. Are people planning to use make-before-break with CDMA
>     with PPP or not?  Or both?  (If PPP is used, I see no
>     problem wrt. DNA as PPP is then the link layer to IPv6,
>     and the situation has to be handled below the IPv6 layer.)

I don't know about the plan but your point looks reasonable.  
 
> 2. Assuming no PPP is used, are there any actual plans of
>     supporting make-before-break between networks that actually
>     have different IPv6 configuration at different base stations?
>     (If not, again, I don't see what we have to worry about.)

As Greg wrote, Flarion wireless technology, Flash OFDM, can support 
make-before-break. Right now they are contemplating only v4 but, 
I'd like DNA schemes be future proof.  
 
> 3. Assuming no PPP is used and make-before-break is supported
>     between base stations that potentially have different
>     network configuration, is there any reason why the link
>     layer cannot model the situation as two different interfaces?

It seems that the link-layer can do that but we need to check it out. 
 
> That is, even in the case that the CDMA link layer does not use
> PPP but is directly visible to IPv6, if we can model the radio
> layer connections to different base stations as different interfaces,
> as seen by IPv6, I don't see any problem.  The worst that can there
> happen is that the two interfaces, corresponding to the two radio
> layer connections, are connected to the same IPv6 network.  But that
> is a case that we have to handle otherwise, too.

I guess that 'two interface approach' will handle the situation. 

However, I think we need to sort out a few the operational details. 

For example, if we model two link-layer connection as two (virtual) interfaces, 
shall we assign the same link-layer address to two interfaces? That may 
bring forth trouble if it happens that two link-layer connections belong to 
the same link. Though, right now, no problem seems insurmountable but 
we'd better think it over.   

> There may be some problems related to link layer addresses, etc,
> but someone should really point us to the right documents, or better,
> write a problem statement draft of the situation, trying to clarify
> the current plans of running IPv6 over make-before-break CDMA (and
> other such radio links). 

It would be nice. 

Best Regards

JinHyeock