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Re: [DNA] Considerations for DNA Schemes with multiple Interface andLayer 2 Technologies
>> I think that the case 3.2, 'Single interface with Make before Break'
>> will affect DNA solution design. I agree that we are not familiar with
>> this case, so it would be of much help, if you elaborate the below
>> with more detail.
>>
>> ... But in CDMA[7], a
>> mobile station can access two or more different base stations
>> simultaneously. In this case, a host can make a new link-layer
>> connection before an old link-layer connection is torn down.
>
> I hope that L2 can actually tell the packets apart.
> If this is possible, then the implementation could present the packets
> from the different links are arriving on different interfaces to IP.
I agree with Erik and others that the apparently cleanest way is
to model the situation with distinct (virtual) interfaces, each
corresponding to a wireless connection.
However, I am also wondering how often we need that in practise.
As far as I've understood (which may be completely wrong), in the
typical case the CDMA network models the whole base station network
as a single link, with a single excess router. OTOH, I have no
idea whether soft handovers between operators is defined or not.
If they are, then we probably need some care there.
Taking a slightly wider angle, we can imagine various anomalies
like someone inadvertedly connecting two (wireline) LAN segments
together. That would (temporarily) create a similar situation.
Hence, I'm afraid that we need to make the DNA scheme(s) robust
against these kinds of situations. However, my current opinion
(subject to change) is that we should not worry too much about
these kinds of situations, and it would be perfectly OK if it takes
some more time to system to recover in such a situation. In other
words, if some hosts unnecessarily run DNA and autoconfiguration,
that wouldn't be too bad.
Network operators have to live with the limits of technology
anyway. If our DNA effort results in a piece of technology that
has a number of well documented limitations, that is OK, as long
as the WG agrees on the limitations.
--Pekka