Re: [v6ops] discussion of transition technologies

Lee Howard <> Tue, 23 January 2018 17:23 UTC

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Date: Tue, 23 Jan 2018 12:23:11 -0500
From: Lee Howard <>
To: Mikael Abrahamsson <>
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Thread-Topic: [v6ops] discussion of transition technologies
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Subject: Re: [v6ops] discussion of transition technologies
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On 1/23/18, 4:13 AM, "Mikael Abrahamsson" <> wrote:

>On Mon, 22 Jan 2018, Lee Howard wrote:
>> That’s a bit of a snarky question, but it’s a real one. Is there any
>> real-world problem for which 6rd is the best answer?
>> “I can’t update my network to support IPv6, but there are IPv6-only
>> that my users need to be able to reach” is the scenario 6rd addresses.
>> that an actual case? The case “My ISP hasn’t updated to support IPv6,
>> there are IPv6-only hosts I need to reach” is solved with a tunnel
>> I don’t deny that it is deployed at scale. I’m asking whether there are
>> any new deployments, recent or contemplated, and what path on a decision
>> tree would lead one to decide “6rd.”
>I know people who seriously are still considering this, because they're
>using old access tech which will never gain native IPv6 capability. So
>it's "6RD" or "no IPv6 at all for the lifetime of the platform".
>Like "we have this ethernet-over-DSL DSLAM from 2006 that seems to still
>work, aggregates a bunch of customers, everybody is in the same VLAN, and
>the vendor has EOLed this platform in 2012, we're seeing declining
>customer base but it's non-zero, and we need IPv6 SAVI functions to
>IPv6 securely". Or "we buy bitstream access over ethernet to a bunch of
>customers, but the bitstream access provider is IPv4 only because
>I just described earlier, and add
>I have talked to multiple people who have pretty compelling business
>reasons not to touch old access platforms, so it's 6RD or nothing. At
>least I haven't been able to come up with something better.

That’s a great example, thank you.

That’s also why I would describe 6rd as declining: its primary use is for
bypassing ISP edge equipment that’s 12 years old and EOL. As time passes,
the number of users behind equipment like that (where “12” continues
incrementing) will continue to decline. If my network was gradually
transitioning from old DSL or DOCSIS1.x, I might suggest enabling IPv6 on
the newer edge boxes and not bothering with the old ones. Or even doing
stateful NAT46 for the very few flows that needed to reach something on

But that’s just me, and I appreciate anyone who is trying to push IPv6 to
those users on older technology.