[arin-ppml] The non-deployment of IPv6

Lee Dilkie Lee at Dilkie.com
Fri Dec 11 10:22:17 EST 2009

Steve Bertrand wrote:
> Lee Dilkie wrote:
>> Don't you essentially *have* multi-homing if you are dual-stack? 
> No. Multi-homing != dual stack. Dual stack can be as simple as having a
> link local v6 address on your machine without even being able to see any
> other v6 devices on the network.
Baloney. A link local address isn't routeable and if that's all that you
have bound to an interface, then you don't have IPv6 nor will the stack
attempt to make any connections over IPv6.

"Multi-homing", the term, refers to multiple methods to access the same
network resource. By that definition, dual-stack suffices. Whether it'll
survive a physical outage is another matter.
>> If you
>> are multi-homed on IPv4, you don't really need it on IPv6, do you?
> Yes, you do (imho). The two are mutually exclusive, even if all of your
> IPv6 transits are over v4 tunnels, redundant paths will better protect
> you from having your v6 prefixes fall off the earth.
And if they do? So what? Your IPv4 connection will be used with no loss
of service. Isn't that what you are looking for?
>> If an
>> IPv6 route is unavailable, the connection will be established on IPv4.
> ...and the time-out value in some applications (such as my preferred SSH
> client for Windows) to fall-over to v4 can become frustrating. For a
> content provider, the time for a browser to switch to v4 when the
> providers internal v6 is unreachable could be potentially disasterous.
I don't disagree that the timeouts can be annoying when there's a
problem in the IPv6 route. So then, start by enabling it on smtp?
Machines are patient and don't mind the 30 second timeout and will
happily retry on IPv4.

>> Multi-homing IPv6 will matter once IPv6-only networks get rolled out and
>> I don't see that happening for some time yet.
> I disagree completely. The same mentality that is applied to v4
> resiliency should be applied all the same to v6. Not only that, it is
> extremely easy to v6 multi-home, as there are several very large ISPs
> who offer *free* peering/transit over tunnels that you can use in
> conjunction with your existing providers. [plug: he.net].
Got it, you don't want to roll out IPv6 and you need excuses to defend
your position. Fine by me.


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