Re: [Roll] [Anima] on the use of RPL without RPI (was Re: [6lo] Adaption of ROLL for mesh-under)

Brian E Carpenter <brian.e.carpenter@gmail.com> Fri, 14 April 2017 20:26 UTC

To: "Pascal Thubert (pthubert)" <pthubert@cisco.com>
References: <1491971619970.42705@ssni.com> <CD3480AD-3934-4C9E-B6F3-E399A32BACC8@tzi.org> <1491974218584.69073@ssni.com> <ae35261f3dac4a9fa123f33610bb9805@XCH-RCD-001.cisco.com> <15236.1492095258@obiwan.sandelman.ca> <6ce1718ab83342bcad9c19d6d9e96935@XCH-RCD-001.cisco.com> <6577.1492101395@obiwan.sandelman.ca> <07e8d178-0545-5fe1-75a6-ecad449565ae@gmail.com> <B8BA574A-EBC0-437A-BD0B-99C9E44C36D1@cisco.com>
Cc: Michael Richardson <mcr+ietf@sandelman.ca>, "roll@ietf.org" <roll@ietf.org>, "anima@ietf.org" <anima@ietf.org>
From: Brian E Carpenter <brian.e.carpenter@gmail.com>
Organization: University of Auckland
Message-ID: <89e0474e-3084-9eae-cdfa-3ae5b7aca65f@gmail.com>
Date: Sat, 15 Apr 2017 08:26:43 +1200
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Subject: Re: [Roll] [Anima] on the use of RPL without RPI (was Re: [6lo] Adaption of ROLL for mesh-under)
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Hi Pascal,

> Would ANIMA wish that ROLL publishes that doc?

I certainly can't speak for the WG, but to me it seems like an issue that
might arise for other use cases, so an answer from ROLL for the general
case seems to make sense.

   Brian
On 14/04/2017 19:28, Pascal Thubert (pthubert) wrote:
> Hello Brian
> 
> This is unspecified since prior to ACP there is always an RPI, thus the need to express it somewhere, which we did in the ANIMA spec; and the problem you raised has 2 sides.
> 
> Could be that nodes always expect an RPI and could be that they never do. Either way nodes may drop the packet in some default: case.
> 
> I think that what we have now at ANIMA works, and that a more complete specification would be useful for a more general case, explaining pro cons of using RPI and in which case mixed mode could work. Would ANIMA wish that ROLL publishes that doc?
> 
> Take care,
> 
> Pascal
> 
>> Le 13 avr. 2017 à 23:31, Brian E Carpenter <brian.e.carpenter@gmail.com> a écrit :
>>
>>> On 14/04/2017 04:36, Michael Richardson wrote:
>>> ...
>>> I also think we could in light of rfc2460bis renegotiation, argue for
>>> insertion of RPI header by the ACP without IPIP encapsulation :-)
>>
>> I wouldn't bet on that for a few more weeks yet. We do have a couple of
>> mitigations however:
>>
>> 1) Since the ACP is strictly using ULAs, we can assert that ACP packets
>> are not intended for the open Internet. It would in fact be tragic for
>> many reasons if an ACP packet "escaped".
>>
>> 2) Since the ACP will be based on IPsec/ESP, we can assert that breaking
>> IPsec/AUTH is not an issue.
>>
>> However, we would also need a story on PMTUD within the ACP.
>>
>>>> So all in all, considering the hassle of updating silicon along the
>>>> forwarding plane, I'd think that living without RPI is fine. Now if you
>>>> tell me that it is always going through software that is easy to
>>>> update, then why not?
>>>
>>> I think that this is the case.
>>
>> Updating the ACP code network-wide, in a large network, might not be so easy.
>> Ignorant question: what happens if only some RPL nodes support RPI?
>>
>>   Brian
>

Re: [Roll] [Anima] on the use of RPL without RPI … Pascal Thubert (pthubert)
Re: [Roll] [Anima] on the use of RPL without RPI … Brian E Carpenter
Re: [Roll] [Anima] on the use of RPL without RPI … Brian E Carpenter
Re: [Roll] on the use of RPL without RPI (was Re:… Michael Richardson
Re: [Roll] on the use of RPL without RPI (was Re:… Pascal Thubert (pthubert)
[Roll] on the use of RPL without RPI (was Re: [6l… Michael Richardson