Le 03/11/2012 19:05, Romain KUNTZ a écrit :
Hello Alex,
On Nov 3, 2012, at 17:53 , Alexandru Petrescu
<[email protected]> wrote:
Le 02/11/2012 20:59, Michael Richardson a écrit :
Alexandru Petrescu <[email protected]> wrote: AP> Well
yes, the prefix allocated to a vehicle when using NEMO is AP>
actually DHCPv6 Prefix Delegation RFC6276. In that RFC the AP>
presence of HA is mandatory.
AP> But some times HA may not be available, e.g. in remote areas
or AP> uncovered areas. There, one would still want vehicles to
AP> inter-communicate.
Yes, so if there is no uplink, then there is no addresses, so
really, it's not an address allocation problem, it's a routing
problem.
In a sense yes.
But let me try to present this better.
I think you agree that, in general, one wouldn't forbid two nearby
vehicles to communicate to each other, even though infrastructure
may not be available in that area. If you differ on this aspect
(like assuming pervasive WMAN everywhere) then please let me know.
When there is no uplink (no WMAN) the negative aspect is that
vehicles can not use MIP-NEMO nor NEMO-DHCP-PD to dynamically
obtain prefixes. The positive aspect is that they can self form
whatever but unique addresses they want, or assign whatever but
routed addresses among them, without fear of disturbing
infrastructure routing, and happily without tunnels either.
Sorry to jump into the discussion. In the case there is no uplink
connectivity, I would tend to say that vehicles would use the prefix
that had been assigned to them previously (when infrastructure was
available and they had connectivity to run NEMO/DHCPv6-PD). Or do
you consider that the LV would never have the capability to connect
to the infrastructure?
HEllo Romain and thank you for discussion.
LV may connect to e.g. house network some times, yes, because it has a
WiFi egress interface. At that point it may acquire a prefix using
MIP-NEMO-DHCP-PD. But would it stay valid after a long disconnection
period? I guess this allocation will behave just like an address
allocated by DHCP - expire after some time. If yes, then the MR-LV
would be prohibited from advertising the prefix inside the vehicle.
(I am not sure this prohibition of advertising an expired prefix is
specified or coded, I just suppose it as natural).
Alex
Thank you, Romain
Whether vehicles self-form addresses and inform each other about
them, or otherwise use a central vehicle to allocate addresses to
each other, is indeed debatable.
I think both paths should be pursued. (I mean I have a draft for
each, and there's a competitor draft for one of them, and I plan
to write another one about self-forming ULAs from VIN and there's
competitor activity on this VIN-ULA.)
AP> Direct communication between vehicles in the absence from AP>
infrastructure is what is being experimented in some settings,
AP> although I agree they may not be reflected in ISO works. I
can AP> speak of the EU project I work on with these V2V and
V2V2I AP> use-cases.
For the scenario involving the roadside and the vehicle, the
prefix can be exchanged as proposed by Lee
(draft-jhlee-mext-mnpp). The solution from Lee is being
integrated in the ISO TC204 standards related to ISO 21210.
AP> I am happy to learn that draft-jhlee-mext-mnpp work is AP>
integrated in ISO TC204 work.
Can you tell us how/if we can view this TC204 work?
Yes, I wonder about this as well. I think Thierry or Jong-Hyouk
are in best position to briefly describe this.
Also, I can not find draft-jhlee-mext-mnpp. Is there a typo?
I think it is http://tools.ietf.org/html/draft-jhlee-mext-mnpp-00
(it may look expired but there is intention on continuing it, I
believe) Is this pointer working for you?
Alex
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