Le 08/11/2012 19:12, Michael Richardson a écrit :
{appologies if this is a resend}
"Alexandru" == Alexandru Petrescu
<[email protected]> writes:
Alexandru> Well yes, let me try to understand what do you mean by
these big picture Alexandru> questions?
1) what use cases need topologically significant prefixes with
default routes
A vehicle assigned with globally-scoped IP subnet, and connecting to the
cellular network must be topologically correct at the point of
attachment, otherwise ingress filtering prevents its communications to CN.
If Mobile IP is used to alleviate this problem (i.e. tunnel to the HA
such that the prefix invalid at that attachment becomes valid thanks to
the topologically correct CoA), then one should consider that HA may not
be reachable sometimes, e.g. because network is down.
Whereas this problem of HA unreachability preventing one vehicle's MR to
communicate to Internet may not be that much apparent, considering that
the MR still has a CoA with wich to communicate.
The problem is more apparent for LFNs (devices) within the vehicle -
they wouldn't be able to communicate when the HA is unreachable.
The problem is further exacerbated when considering LVs (Leaf Vehicles -
capable of doing only short range link layers, no SIM card). These LVs
are not capable to communicate to Internet (neither their LVs nor their
LFNs) when the IV's HA is unreachable.
2) what use cases need to exchange routes to locally configured
Non-Connected Network prefixes (whether RIR NCN, or ULA)
There are a number of specific vehicular communications use cases which
need one vehicle to communicate to another even though the
infrastructure is not available.
I mention one just for example but there are many others.
'Platooning' involves a chain of one 'head' larger vehicle which
dictates speed to vehicles behind it in a chaining like fashion. This
is typically achieved with onboard radars (and maybe lasers?) but there
exist certain needs (ask) to move this to IP communications. One
possible way is for the 'head' to sample its GPS location at very high
frequency and transmit it to the next vehicle which in turn decides fine
up/down speed steps. This communication pattern does not need global
addressing - ULA is sufficient. The ends of the communications are
within this ephemeral platoon only.
Other more entertainment 'V2V' communications involve video conferencing
between passengers of vehicles, and more.
Those two situations need to be seperated. They are not the same
thing, or the same problem.
Ok, I agree to separate the situations.
In case #1, one needs to further split this into 1a) managed
situations where all systems are under the control of a single
administrator (aka "intra-AS")
1b) unmanaged situations where an individual lends another
individual some bandwidth.
Yes, I agree.
(1b) seems really easy in today's multiply NAT'ed IPv4, because the
NAT erases all evidence that first individual might have violated an
AUP. (I disagree with those AUPs)
Well ok and it seems impossible with non-NAT IPv6.
Alex
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