Subject: Re: [homenet] The minimal Babel profile for Homenet

From: "STARK, BARBARA H" <[email-masked]>
Date: Mon, 2 Nov 2015 20:57:25 +0000

>     > Maybe conditionally mandatory? If the router can be used for routing
> 
> That's what SHOULD is *for*
> If you are concerned it won't get implemented, then any weasel room you
> leave will be exploited.  At that point, the market gets to decide.

<on vacation, so not responding quickly and not in Yokohama>
No, SHOULD and conditionally mandatory are 2 very different types of requirements. When designing a test tool to automate testing of requirements, a tool generally issues a warning when a "SHOULD" is not implemented (correctly). But for conditional mandatory, a tool will test for the condition and then issue a failure if the requirement is not implemented (correctly). But I agree that in IETF, I haven't seen use of conditional mandatory. I think that's unfortunate and I think this is the reason many IETF "SHOULD" requirements aren't implemented when they need to be implemented. 

But I'm not willing to spend more time arguing in this particular case. CE router vendors are a tremendously pragmatic bunch. If it's easy and could cause dissatisfaction with their product if not implemented, they will more than likely do it. This looks pretty easy to me, especially with the availability of a lot of open source code for it.
Barbara

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From: Michael Richardson <[email-masked]>
Date: Tue, 03 Nov 2015 19:06:15 +0900

STARK, BARBARA H <[email-masked]> wrote:
    > But I'm not willing to spend more time arguing in this particular
    > case. CE router vendors are a tremendously pragmatic bunch. If it's
    > easy and could cause dissatisfaction with their product if not
    > implemented, they will more than likely do it. This looks pretty easy
    > to me, especially with the availability of a lot of open source code
    > for it.

Agreed.

-- 
Michael Richardson <[email-masked]>, Sandelman Software Works
 -= IPv6 IoT consulting =-

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From: Lorenzo Colitti <[email-masked]>
Date: Tue, 3 Nov 2015 23:29:59 +0900

On Wed, Oct 28, 2015 at 10:07 PM, Juliusz Chroboczek <
[email-masked]> wrote:

> Fully agreed, but I'm not sure what is the WG's thinking about IPv4.  RFC
> 7368 (Homenet arch) is conveniently vague about IPv4.  My reading is that
> the authors of RFC 7368 expected that router vendors will use multiple NAT
> for IPv4, and that they will ignore whatever we mandate.
>

I think the base view is, "we'll spec things for IPv6; if IPv4 gets the
benefit, so much better".

In this case... what's do we get from doing src/dest routing for IPv4 given
that a host only ever has one IPv4 address? Is it just that we get
dest-based routing without NATs in the way? But if so, then how does IPv4
renumbering work without NAT?

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From: Juliusz Chroboczek <[email-masked]>
Date: Tue, 03 Nov 2015 17:30:37 +0100

> benefit, so much better".

Very well put, but not exactly what happens with HNCP, which specifies
things fairly precisely for IPv4.  (A good thing, IMHO.)

> In this case... what's do we get from doing src/dest routing for IPv4
> given that a host only ever has one IPv4 address?

In a typical Homenet, we're not doing source-specific for IPv4.  HNCP
elects a single NAT router that delegates 10/8.  HNCP is a little vague
about whether all NAT gateways announce a (non-specific) IPv4 default
route -- hncpd/OpenWRT pushes traffic through all NAT gateways, while by
default shncpd pushes all traffic through the router doing the delegation.

(More precisely, HNCP says which routers must announce routes into the
routing domain, but doesn't specify whether any other routes can be
announced.  Hncpd/OpenWRT announces all available routes, while shncpd
performs careful filtering in order to only announce the minimal set of
routes.  A clued administrator can add filtering rules to announce
additional routes, of course, and since babeld's config file format easy
to generate, this could be a point-and-click configuration item.)

-- Juliusz