Re: [Autoconf] RFC 5889 (Was: Call for comments to a new AUTOCONF charter proposal)

Alexandru Petrescu <alexandru.petrescu@gmail.com> Thu, 08 July 2010 17:48 UTC

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Date: Thu, 08 Jul 2010 19:48:26 +0200
From: Alexandru Petrescu <alexandru.petrescu@gmail.com>
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Subject: Re: [Autoconf] RFC 5889 (Was: Call for comments to a new AUTOCONF charter proposal)
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Le 29/06/2010 23:55, Jari Arkko a écrit :
> Christopher,
>
>> Incidentally the charter refers to RFC 5889, which is not yet
>> published. I see that is in AUTH48, but noted as on hold for a
>> technical issue. AUTH48 seems rather late for a technical issue,
>> unless meaning a publication technical issue rather than an
>> engineering technical issue.
>
> Yes it is late. We approved the document but after approval there was
> a comment on the IETF last call thread from Erik Nordmark. We are
> trying to resolve it but unfortunately it took a long time for me to
> do so. But we are now trying to do it. The standing proposal is
> below, comments appreciated.

Jari - I am ready to spend time reading and trying to understand.  I am
ready to give my oppinion about this last point - the IPv6 link-local
addresses.

If asked whether I agree with the NEW text on LLs then I say no, I do
not agree with it.  It is better than the old text but still makes
little sense to my reading (e.g. "IPv6 ll addresses are not unique
across links" is a statement which makes little sense, an answer to
something nobody doubted; worst, to derive conclusions saying that LL
addresses are not useful in "MANET ad-hoc" networks because of their
lack of uniqueness is even less sense.)

My two cents worth,

Alex

>
> Jari
>
> -----
>
> We talked about this during Anaheim but never got to the end of it.
> Sorry -- I should have posted a suggestion back then but other
> business has kept me busy. I have now looked at the discussion
> again.
>
> The essence of Erik's complaint was twofold. First, the document
> claimed that routing protocols require a unique IP address (and not
> just a router ID), which is not true. Second, that the document
> unnecessarily dismisses link local identifiers as addresses.
>
> About the first issue: Erik is right that not all routing protocols
> require unique IP addresses at all. But at the same time, apparently
>  some routing protocols in the MANET space do require it (e.g., OSLR
>  in RFC 3626). In a way, the document is factually correct on this
> point as it states that some protocols do have these requirements.
> But it may also be misleading from another perspective, as we
> certainly do not want to claim that using unique IP addresses is a
> recommended design for a routing protocol or the only possible
> model.
>
> The second issue is partially related to the first one, as one of the
> reasons for using non-link-local addresses is to enable the use of
> unique addresses in routing protocols. In any case, the intent was
> never to claim that link local addresses cannot be used. The document
> merely makes one recommendation about a commonly used addressing
> model in adhoc networks. I would like to defend the working group's
> right to publish such an "example model" -- particularly after years
> of effort spent in trying to find the true universal model. As long
> as the working group is not making false claims, this is clearly
> appropriate. But I can see that the document could be clearer about
> its claims.
>
> Here's a possible rewrite of Section 5 to address these issues:
>
> OLD: Routing protocols running on a router may exhibit different
> requirements for uniqueness of interface addresses; some have no
> such requirements, others have requirements ranging from local
> uniqueness only, to uniqueness within, at least, the routing domain
> (as defined in [RFC1136]).
>
> Configuring an IP address that is unique within the routing domain
> satisfies the less stringent uniqueness requirements of local
> uniqueness, while also enabling protocols which have the most
> stringent requirements of uniqueness within the routing domain. This
> suggests the following principle:
>
> o an IP address assigned to an interface that connects to a link with
> undetermined connectivity properties should be unique, at least
> within the routing domain. NEW: Routing protocols running on a router
> may exhibit different requirements for uniqueness of interface
> addresses; some have no such requirements, others have requirements
> ranging from local uniqueness only, to uniqueness within, at least,
> the routing domain (as defined in [RFC1136]). Many modern routing
> protocols do not need to employ unique addresses at all, and
> theoretically, their only requirement is that some router identifier
> is unique.
>
> Nevertheless, configuring an IP address that is unique within the
> routing domain satisfies the less stringent uniqueness requirements
> of local uniqueness, while also enabling protocols which have the
> most stringent requirements of uniqueness within the routing domain.
>  As a result, many current deployments have chosen to employ the
> following simplifying principle:
>
> o an IP address assigned to an interface that connects to a link with
> undetermined connectivity properties should be unique, at least
> within the routing domain.
>
> And in Section 6.1:
>
> OLD: o There is no mechanism to ensure that IPv6 link-local addresses
> are unique across multiple links, hence they cannot be used to
> reliably identify routers (it is often desirable to identify a router
> with an IP address). NEW: o There is no mechanism to ensure that IPv6
> link-local addresses are unique across multiple links, hence they
> cannot be used to reliably identify routers, should this be necessary
> in the chosen routing protocol.
>
> OLD: Therefore, autoconfiguration solutions should be encouraged to
> primarily focus on configuring IP addresses that are not IPv6 link-
> local. NEW: Therefore, a common theme in many autoconfiguration
> solutions is to focus on configuring IP addresses that are not IPv6
> link- local.
>
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