[ipwave] draft-ietf-ipwave-ipv6-over-80211ocb and draft-ietf-ipwave-vehicular-networking

[Brian E Carpenter <[e-mail]>]

Hi,

I have just discovered a useful discussion of the multi-link problem here:

https://tools.ietf.org/html/draft-ietf-ipwave-vehicular-networking-08#section-5.1.1

The OCB draft doesn't refer to this draft, but only to its superseded
predecessor draft-ietf-ipwave-vehicular-networking-survey.

I think I will drop this discussion until ipwave gets its two
main drafts properly synchronized.

Regards
   Brian

On 16-Apr-19 09:04, Brian E Carpenter wrote:
> Excuse top posting. 
> 
> As I've said, I am no expert, but I do know some physics, and
> it seems pretty clear to me that if there are multiple lanes 
> of traffic, a large truck can easily shield signals between
> two cars and the shielding will be intermittent, regardless
> of how much wireless power is allowed, depending on traffic
> movement. So it's a highly dynamic mesh network. That's a very
> interesting problem that has been much studied, and it's
> fundamentally different from the ND design scenario.
> 
> So I find it hard to believe that nobody can write the TBD
> text.
> 
> Regards
>    Brian
> 
> On 15-Apr-19 23:26, Alexandre Petrescu wrote:
>> Hi Brian,
>>
>> Le 14/04/2019 à 22:49, Brian E Carpenter a écrit :
>>> Hi Alexandre,
>>>
>>> On 15-Apr-19 04:38, Alexandre Petrescu wrote:
>>>> Brian,
>>>>
>>>> Le 14/04/2019 à 04:20, Brian E Carpenter a écrit :
>>>>>>> All we need is a simple statement in the spec which puts some scope
>>>>>>> limits, w.r.t the missing ND pieces and issues.
>>>>>
>>>>> Yes, that is clearly essential, as well as an associated health
>>>>> warning that implementers must not rush ahead because of the risk
>>>>> of non-interoperability.
>>>>
>>>> There is already paragraph, and an Appendix, about potential ND issues.
>>>> I think that text qualifies as an associated health warning.
>>>>
>>>> I do not know what do you mean about the risk of interoperability.  This
>>>> ND that works is interoperable between several OCB cards, IP Road Side
>>>> Units, and linuces. (I can cite brands that I al familiar with and that
>>>> interoperate.
>>>>
>>>> This is the current paragraph and Appendix that qualify as a warning
>>>> that you suggest:
>>>>
>>>>>     The baseline Neighbor Discovery protocol (ND) [RFC4861] MUST be used
>>>>>     over 802.11-OCB links.  Transmitting ND packets may prove to have
>>>>>     some performance issues.  These issues may be exacerbated in OCB
>>>>>     mode.  Solutions for these problems SHOULD consider the OCB mode of
>>>>>     operation.  The best of current knowledge indicates the kinds of
>>>>>     issues that may arise with ND in OCB mode; they are described in
>>>>>     Appendix J.
>>>
>>> That's exactly the text that I find problematic. I can't write a new
>>> version because I lack your expert knowledge, but IMHO it should be
>>> more specific:
>>>
>>>      The baseline Neighbor Discovery protocol (ND) [RFC4861] MUST be used
>>>      over 802.11-OCB links.  However, as on any wireless link, transmission
>>>      of multicast ND packets may fail in OCB. In particular, scenarios
>>>      where TBD TBD TBD are likely to be unreliable and SHOULD NOT be
>>>      deployed until an alternative standardised solution is available.
>>>      The best of current knowledge indicates the kinds of issues that
>>>      may arise with ND in OCB mode; they are described in Appendix J.
>>
>> I can agree with that formulation and put it in the text.
>>
>> But I need an indicat that TBD is defined soon.  The time commitments of 
>> Pascal seem to be saying he is no longer interested in writing that TBD.
>>
>> I wait a little for this to clarify.
>>
>>> Also I don't like this phrasing in Appendix J:
>>>
>>>     Early experiences indicate that it should be possible to exchange
>>>     IPv6 packets over OCB while relying on IPv6 ND alone for DAD and AR
>>>     (Address Resolution).
>>>
>>> Could you rather say the opposite:
>>>
>>>     Early experience indicates that it is possible to exchange
>>>     IPv6 packets over OCB while relying on IPv6 ND alone for DAD and AR
>>>     (Address Resolution) in good conditions. However, this does not
>>>     apply if TBD TBD TBD...
>>
>> This is an appendix.  I could put TBD there now.
>>
>> Alex
>>
>>>
>>> Regards
>>>      Brian
>>>
>>>
>>>>
>>>>
>>>> Alex
>>>>
>>>>>
>>>>> Regards
>>>>>      Brian
>>>>>
>>>>> On 14-Apr-19 13:58, NABIL BENAMAR wrote:
>>>>>> +1 Sri
>>>>>>
>>>>>> On Sun, Apr 14, 2019, 00:06 Sri Gundavelli (sgundave) <[e-mail] <mailto:[e-mail]>> wrote:
>>>>>>
>>>>>>       I understand your point Brian, but IMO there are enough reasons not to
>>>>>>       delay this work.
>>>>>>
>>>>>>       There are many use-cases/applications where there is a stable topology of
>>>>>>       RSU¹s and OBU¹s. The regulations around 5.9 Ghz (DSRC) band allows the
>>>>>>       channel use for non-priority/non-traffic safety related applications. For
>>>>>>       example, a vehicle in a gas station can receive a coupon from the
>>>>>>       802.11-OCB radio (AP/RSU) in the gas station. There, its a stable topology
>>>>>>       that classic ND is designed for. In this operating mode, its perfectly
>>>>>>       reasonable to use classic ND and it works. The authors have shown enough
>>>>>>       lab data on the same.
>>>>>>
>>>>>>       Ideally, I agree with you that it makes lot more sense to publish both the
>>>>>>       specs at the same time. But, for what ever reasons the WG went on this
>>>>>>       path. Authors have spent incredible amount of efforts in getting the draft
>>>>>>       this far and we cannot ignore that. You can see the efforts from the
>>>>>>       version number; when did we last see a draft version -037?
>>>>>>
>>>>>>       We also need to distill the recent ND discussions and filter out the
>>>>>>       threads that are clearly motivated to insert a ND protocol that is
>>>>>>       designed for a totally different operating environment. An argument that a
>>>>>>       protocol designed for low-power environments is the solution for vehicular
>>>>>>       environments requires some serious vetting. Looking at the
>>>>>>       characteristics, always-sleeping, occasional internet connectivity,
>>>>>>       low-power, no memory, no processing power, no mobility ..etc, meeting
>>>>>>       vehicular requirements is some thing most people in the WG do not get it.
>>>>>>
>>>>>>       Bottom line, IMO, we should move this forward and publish the document.
>>>>>>       All we need is a simple statement in the spec which puts some scope
>>>>>>       limits, w.r.t the missing ND pieces and issues. There are other proposals
>>>>>>       in the WG that will address the gaps and bring closure to the work.
>>>>>>
>>>>>>       Sri
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>       On 4/12/19, 1:28 PM, "Brian E Carpenter" <[e-mail] <mailto:[e-mail]>>
>>>>>>       wrote:
>>>>>>
>>>>>>       >On 13-Apr-19 02:59, Sri Gundavelli (sgundave) wrote:
>>>>>>       >>If you go back and check 2017 archives, I did raise many of these
>>>>>>       >>issues.  But, we clearly decided to limit the scope excluding address
>>>>>>       >>configuration, DAD, ND aspect, link models. When there is such a scope
>>>>>>       >>statement, it should clearly move these comments to the draft that
>>>>>>       >>defines how ND works for 802.11-OCB links.
>>>>>>       >
>>>>>>       >This is of course possible. In general the IETF hasn't done that, but has
>>>>>>       >followed the lead set by RFC 2464 with the complete specification of
>>>>>>       >IPv6-over-foo in one document.
>>>>>>       >
>>>>>>       >However, I don't believe that publishing an RFC about the frame format
>>>>>>       >without *simultaneously* publishing an RFC about ND etc would be a good
>>>>>>       >idea. That would leave developers absolutely unable to write useful
>>>>>>       >code, and might easily lead to incompatible implementations. Since
>>>>>>       >we'd presumably like Fords to be able to communicate with Peugeots,
>>>>>>       >that seems like a bad idea.
>>>>>>       >
>>>>>>       >Regards
>>>>>>       >   Brian
>>>>>>
>>>>>
>>>>>
>>>> .
>>>>
>>>
>>>
>>
>