Re: [v6ops] new draft: draft-byrne-v6ops-clatip

"cb.list6" <> Thu, 31 October 2013 14:04 UTC

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Date: Thu, 31 Oct 2013 07:04:20 -0700
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From: "cb.list6" <>
To: "Eric Vyncke (evyncke)" <>
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Subject: Re: [v6ops] new draft: draft-byrne-v6ops-clatip
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Thanks Eric

On Oct 31, 2013 5:29 AM, "Eric Vyncke (evyncke)" <> wrote:
> Cameron
> As you asked for a quick review, here we go :-)
> Getting a CLAT prefix from IANA sounds logical for me as we cannot
'steal' a prefix from someone else. This would also allow some IPv4-only
application to detect CLAT (and possibly force the use of IPv6 even if
happy eyeball is not happy).

In theory, yes, but 464xlat is only a band-aid for the most archaic apps,
so I find it frustrating if someone tried to modify their app to have logic
to use or not use CLAT instead of enabling ipv6 or generically using HE.
Your line of thinking is correct in practice, I just dont like this certain
reality :)

In any event, the path in the i-d is to generalize the ds-lite range,  such
that in one step an app could know they are not on true dual-stack, they
are on some overlay.

> My concern about re-using the DS-lite prefix is when (if ever) the CLAT
will then go over DS-lite in some weird (home?) network configurations...
This would confuse traceroute and possibly other ICMP mechanisms.

The address is never on the wire from CLAT, and that topology should never
occur since both 464xlat emit only ipv6, so there should be no case where
the transition happens twice AND that on-path address responds...

But you made me think about the case of  tracerouting from 464xlat node to
a ds-lite node across the ipv6 internet... And  that b4 does not use the
specific addresses reserved for b4s.  In this case, the b4 can send a icmp
ttl exceeded to the clat, where the clat will see the packet with a
possible same source and destination

> Sharing the DS-lite prefix also prevents a dual-stack measurement apps to
detect whether it uses DS-lite or CLAT for the IPv4 path. About
measurements, it is really easy to detect Teredo & 6to4 but much less 6RD
(if you do not have the IPv4 address). So, 'just for measurements' I would
love to have another prefix for CLAT

Another  prefix dedicated for CLAT is an option.  Thanks for the feedback.

> Hope this helps
> -éric
> > -----Original Message-----
> > From: [] On Behalf
> > Fred Baker (fred)
> > Sent: vendredi 11 octobre 2013 14:45
> > To:
> > Cc:
> > Subject: [v6ops] new draft: draft-byrne-v6ops-clatip
> >
> >
> > A new draft has been posted, at
> > v6ops-clatip. Please take a look at it and comment.
> > _______________________________________________
> > v6ops mailing list
> >
> >
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