Re: [ipwave] which BSM?

[Alexandre Petrescu <[e-mail]>]

Le 16/04/2019 à 12:12, William Whyte a écrit :
> That's a decision made further up the stack. It's not part of the scope 
> of this group.
> 
> For what it's worth: In the US, the BSM-based applications are based on 
> SAE J2945/1 and SAE J2735-2016 and sent over WSMP. In Europe, 
> cooperative awareness using CAM is based on EN 302 637-2 and sent over 
> BTP. But even if BSMs were sent over IP, the version of BSM used would 
> be out of scope for this group. That's how layered systems work.

I agree layered systems are good to focus, and interfaces.

I think that an overarching CAM-BSM message put on UDP/IP specified at 
IETF may get benefits beyond just layering and interfaces.

Such a spec would tell, for example, that in worst case the cars MUST 
accept both EtherTypes (dont drop either), by the principle of being 
conservative on what to accept.  And in best case expect an IPv6 
EtherType that carrying an IP datagram carrying an overarching BSM-CAM.

That could probably improve safety in some situations.

It is also true that that is a standpoint of IP packets being the same 
all over the world, whereas cars are not really the same.  E.g. in 
America the cars are allowed to have both left and right yellow lights 
turned on permanently, but not in other parts of the world.

So I am really not sure whether an idea of an overarching CAM-BSM over 
IP can ever fly, even though I like it.

Alex

> 
> William
> 
> - sent from my phone
> 
> On Tue, Apr 16, 2019, 11:45 AM Alexandre Petrescu 
> <[e-mail] <mailto:[e-mail]>> wrote:
> 
>     Which network/transport do BSMs use?
> 
>     Alex
> 
>     Le 16/04/2019 à 11:40, William Whyte a écrit :
>      > I don't fully understand why IPWAVE, which is about network /
>     transport
>      > protocols, needs to have an opinion about what form of BSM to use.
>      >
>      > Cheers,
>      >
>      > William
>      >
>      > On Tue, Apr 16, 2019 at 10:58 AM Alexandre Petrescu
>      > <[e-mail]
>     <mailto:[e-mail]>
>     <mailto:[e-mail]
>     <mailto:[e-mail]>>> wrote:
>      >
>      >     Sri,
>      >
>      >     Thank you very much for the email.
>      >
>      >     I would like to take this opportunity to discuss publicly a
>     particular
>      >     topic in your email, that we already touched upon in private
>     a few
>      >     months ago.
>      >
>      >     I purposefully keep the other ideas of you out of this email,
>     but I do
>      >     agree with very many of them.
>      >
>      >     Le 16/04/2019 à 05:11, Sri Gundavelli (sgundave) a écrit :
>      >     [...]
>      >      > From the point of view of vehicular safety, its about
>     exchange of
>      >      > BSM (Basic Safety Messages) between vehicles as per SAEJ735
>      >      > standard.
>      >
>      >     Sri, but there are at least three versions of BSM.
>      >
>      >     Which BSM do you mean?
>      >
>      >     Why SAE and not ISO?  Both have 'International' in their names.
>      >
>      >     Why SAE 2016 and not SAE 2009?
>      >
>      >     - SAEJ2735 version 2009 (free access),
>      >         (google hits "SAE J2735")
>      >     - SAEJ2735 version 2016 (paid access, cca 100 USD),
>      >         (google hits "SAE J2735")
>      >     - and the ISO/CEN/ETSI versions (free access):
>      > https://www.tc278.eu/cits
>      > https://standards.iso.org/iso/ts/19091/addgrp_c
>      >
>      >     (remark I dont mention ETSI CAM, which is ITS safety in Europe).
>      >
>      >     The three seem to be different in contents, to a few people. 
>     Myself I
>      >     identified the first and second to be distinct.
>      >
>      >     Ideally, safety would be just one standard, right?  Something
>     like a
>      >     combination of all BSM versions with the CAM version running on a
>      >     transport that is common to all.
>      >
>      >     A safe car would need to be able to understand all these CAM
>     and BSM
>      >     versions; if it misses just one because of some syntax error,
>     well,
>      >     safety would be at stake.
>      >
>      >      > [...] and for very good reason IEEE WAVE standards did not
>     bother to
>      >      > require IPv6 transport for carrying these messages.
>      >
>      >     I doubt that reason.
>      >
>      >     Alex
>      >
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>      >
>      >
>      > --
>      >
>      > ---
>      >
>      > I may have sent this email out of office hours. I never expect a
>      > response outside yours.
>