Re: Consensus Call: draft-weil-shared-transition-space-request

Chris Donley <C.Donley@xxxxxxxxxxxxx> · Tue, 29 Nov 2011 14:59:07 -0700

And that's one of the reasons this draft updates 5735. If routers make decisions as to whether or not to enable a feature based on whether behind a public or private address, having a defined address range for CGN space will be significantly easier to deal with than to have arbitrary address ranges selected on a per-ISP basis.

Chris

From:  Mark Townsley <mark@xxxxxxxxxxxx>
Date:  Tue, 29 Nov 2011 14:02:34 -0700
To:  Ronald Bonica <rbonica@xxxxxxxxxxx>, Chris Donley <c.donley@xxxxxxxxxxxxx>
Cc:  IESG IESG <iesg@xxxxxxxx>, IETF Discussion <ietf@xxxxxxxx>
Subject:  Re: Consensus Call: draft-weil-shared-transition-space-request

On Nov 29, 2011, at 9:13 PM, Chris Donley wrote:

Ron,

One point of clarification, in your *against* list, you include:

On 11/28/11 2:25 PM, "Ronald Bonica" <rbonica@xxxxxxxxxxx> wrote:

- Some applications will break. These applications share the
characteristic of assuming that an interface is globally reachable if it
is numbered by an non-RFC 1918 address. To date, the only application
that has been identified as breaking is 6to4, but others may be
identified in the future.

Since this address space is between the CPE router and CGN device, and is
therefore not globally routable, the same application(s) (e.g. 6to4) will
break if public or 'squat' space are used instead of shared CGN space.
Such applications rely on the home router detecting that there is private,
non-globally routable space (i.e. RFC1918) on the WAN and disabling such
an application.  While that same detection code will always fail for
public address space and squat space since the exact range is not defined,
there is the possibility of fixing the detection code in home routers if
we do define shared CGN space for that purpose.

http://tools.ietf.org/html/draft-ietf-v6ops-6204bis-03 has this requirement:

   DLW-4:  If the IPv6 CE Router is configured with a public IPv4
           address on its WAN interface, where public IPv4 address is
           defined as any address which is not in the private IP address
           space specified in [RFC5735], then the IPv6 CE Router SHOULD
           disable the DS-Lite B4 element.

I'm not sure I personally agree with this requirement, but suffice to say if this kind of language is popping up in our own v6ops documents at this very moment, there is a decent chance that it has made its way into specifications and code elsewhere.

- Mark

Chris

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