IPV6 in enterprise best practices/white papaers

William Herrin bill at herrin.us
Sun Jan 27 17:31:37 UTC 2013

On Sat, Jan 26, 2013 at 5:38 PM, Mark Andrews <marka at isc.org> wrote:
> In message <CAP-guGX01KLj2cG3ASmfXbmpxZ6j=i1b0DZ++s4-W8Uq_vy-5Q at mail.gmail.com>, William Herrin writes:
>> In their infinite(simal) wisdom the architects of IPv6 determined that
>> a host configured with both a global scope IPv6 address and an IPv4
>> address will attempt IPv6 in preference to IPv4. If you configure IPv6
>> on a LAN without first installing your IPv6 Internet connection, that
>> LAN will break horribly.
> The default is to tune for IPv6 first but it been configurable for
> years now.  Given one generally wants to use IPv6 over IPv4 to avoid
> having you packets going through CGN boxes this is a good thing for
> you and your ISP.

Right. On a each local machine you can often override the default
behavior. That default dynamically kicks in for all machines as soon
as there's an IPv6 router on the LAN. Configurable? Sort of. Realistic
solution to the cited problem? Not in your wildest dreams.

> As for "breaking" your LAN, if the applications take 60 seconds to
> fallback to the other address they were already broken.  Go complain
> to your application vendor.  Some vendors have already fixed this
> problem with their applications.

That's right, blame the applications for the defective API. After all,
any skilled application programmer can work around the problem, given
sufficiently long experience with IPv6.

Bill Herrin

William D. Herrin ................ herrin at dirtside.com  bill at herrin.us
3005 Crane Dr. ...................... Web: <http://bill.herrin.us/>
Falls Church, VA 22042-3004

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