Re: [Anima] Rtgdir last call review of draft-ietf-anima-autonomic-control-plane-24

Brian E Carpenter <> Fri, 10 April 2020 23:03 UTC

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To: "Joel M. Halpern" <>, Michael Richardson <>,,,,
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From: Brian E Carpenter <>
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Date: Sat, 11 Apr 2020 11:03:20 +1200
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Subject: Re: [Anima] Rtgdir last call review of draft-ietf-anima-autonomic-control-plane-24
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On 11-Apr-20 09:35, Joel M. Halpern wrote:
> I am happy to propose some starting text (I am sure it will need further 
> tuning) as a short definition of a Loopback Interface:
>      Loopback Interface: A logical or virtual representation of
>      connectivity for IP communication.  It is distinct from any
>      physical interface on the device.  It is typically used to
>      abstract a point of communication from any physical connectivity.

That would work for me.
> If we want to elaborate, we could not that this provides an interface to 
> anchor IPv6 addresses in accordance with the IPv6 addressing architecture.

Right. That's the only thing that's different from the IPv4 case.

> As for the L2 material, if the WG wants to remove it, I would be fine 
> with that.  It is clearly supplementary.  I am just trying to avoid 
> confusion if we choose to describe it.
> Yours,
> Joel
> On 4/10/2020 5:27 PM, Michael Richardson wrote:
>> Joel M. Halpern <> wrote:
>>      > On Loopback, I understand your frustration with the lack of a good
>>      > definition.  Given that IPv6 addressing architecture constraints, you need
>>      > some sort of interface.  In practice, the way loopbacks are used seems to
>>      > match the need.  So I do not object to the usage.  just to the definition.
>>      > It would also be acceptable to simply craft a different term and clearly
>>      > define it if the usage is sufficiently different from existing
>>      > practice.
>> Reading this thread, I was hoping you might be able to help us with a better
>> definition then :-)
>> We are doing exactly what OSPF and BGP does operationally on every platform
>> that I have every worked on.  We are just doing it with RPL.
>> To me, it's *SO* obvious that it goes without saying, so now we are asked to
>> say it, and we get into trouble because nobody before us bothered to say it.
>>      > On the final minor comment, it was specifically about the section on L2
>>      > devices.  Maybe something special is needed for the special case of a shared
>>      > network that is also a border network.  But that seems very rare. And getting
>>      > the L2 switch to do the right packet forwarding for the hybrid case seems an
>>      > invitation to trouble.
>> I'm not happy about any of the L2 text; I would have left it out completely.
>> --
>> Michael Richardson <>ca>, Sandelman Software Works
>>   -= IPv6 IoT consulting =-