Re: [ipwave] Intdir early review of draft-ietf-ipwave-ipv6-over-80211ocb-34 - link vs subnet clarification in V2V convoy

[Alexandre Petrescu <[e-mail]>]

Le 04/03/2019 à 12:24, Pascal Thubert a écrit :
> Reviewer: Pascal Thubert Review result: Not Ready
[...]
> " A subnet is formed by the external 802.11-OCB interfaces of
> vehicles that are in close range (not by their in-vehicle
> interfaces). " Is the definition transitive? Do we really get a
> subnet? A is close to  B who is close to C .... to Z, makes Paris one
> subnet! Are you talking about a link, rather?

Allow me to clarify.

I do not know whether the definition mentioned above is transitive.  A
transitive characteristic is the following: A talks to B, and B talks to
C results in A talks to C.

In the V2V settings I use there does not seem to be any transitivity.
There is a convoy of cars; there are distinct subnets between each pair
of two  cars (or sometimes between triplets of cars).  Within these
subnets there does not seem to be transitivity.

If interested, yes, there is IP forwarding: one PC in Lead vehicle
receives replies to ICMP Echo Replies to its Echo Requests addressed to
another PC in the rearmost vehicle.  The ICMP messages are forwarded by
intermediary IP-OBUs (Routers) situated in each car.

In this setting, there are 2 or 3 EThernet and CAN links in each car,
and there are distinct IP subnets on OCB between each pair (or triplet
in some cases) of cars.

Each such subnet of IP-over-OCB is run on one of the 5 possible OCB
channels in the 5.9GHz range.  The selection of these channels is a
method that I will not describe here.

Does this clarify?

If not, would you like the text to say it is not transitive?

If yes, I propose:

NEW:
> A subnet is formed by the external 802.11-OCB interfaces of vehicles 
> that are in close range (not by their in-vehicle interfaces).  This
> definition is not transitive.

Do you agree with this text?

Alex