Notice: IPv6 breaking issues tentatively considered blocker for F17

Tore Anderson tore at
Mon Mar 12 23:33:49 UTC 2012

* Dan Williams

> On Mon, 2012-03-12 at 09:59 -0600, Pete Zaitcev wrote:
>> This may be the case for the network that you or I run, but not for
>> providers. Comcast require DHCPv6 (otherwise they can't delegate
>> /64 automatically).
> Do they send RAs at all?  If so, which (if either) of the "other"
> and "managed" flags are set?  If they don't, do they just expect
> DHCPv6 to be magically run, and what gets used for the default
> gateway address given that DHCPv6 has no such option?  I'd love to
> know...

Hi Dan,

Assuming Comcast use plain Ethernet, I am certain they will send RAs
with M=1.

That said, you *are* allowed to kick off DHCPv6 before receiving an RA
in order to speed up the activation process. However, if you do, you
need to always request an IA_NA address (in other words behave as if
you're expecting an RA with M=1). Microsoft Windows does this.

Without an RA, however, you won't get on the internet, as RAs are the
only way to discover the default router(s). So waiting for an RA before
starting DHCPv6 (like currently NM does) is perfectly reasonable too,
perhaps even more so at this point in time, where most networks have
neither RAs or DHCPv6 service.

Best regards,
Tore Anderson

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