[GRLUG] Comcast dual stack IPV6 spotted in Muskegon

Adam Tauno Williams awilliam at whitemice.org
Sun Nov 24 20:54:58 EST 2013

On Sun, 2013-11-24 at 15:34 -0500, Mike Williams wrote:
> What's a PD in this context?

Prefix Delegation

It has to do with setting the IPv6 [sort of] equivalent of the subnet
mask for the router's LAN.

For whatever reason DHCP is one area where IPv6 is really hacked up
[IMHO].  They had the opportunity to redesign/fix auto-discovery &
assignment but made a total hatchet job out of it.  So you have the
elegant Router Announcement scheme but end up having to use DHCP with a
bunch of extensions all over again.

IPv6 is simply a *better* protocol than IPv4, and strips away decades of
accumulated hacks.  But the DHCP... ugh, it is as sucky as IPv4.

In its defense IPv6 is intended to support a *much* larger network than
IPv4, so some of this is inevitable - but why you need DHCP on top of RA
and autoconfig.  I dunno, it feels kludgy.  Why can't additional
attributes just be encoded in the RA for a specific interface... ?
Perhaps the need for the upper tier router to retain a state/assignment
is the reason?

> You'll need a DOCSIS 3.0 modem a router that supports both IPV6 and
> DHCPV6-PD for it to work with Comcast. DD-WRT does not unless you
> already have a version that supports IPV6 and hack in some packages
> from OpenWRT to provide a dhcp client for IPV6.  DD-WRT does not
> support ip6tables at all.

Adam Tauno Williams <mailto:awilliam at whitemice.org> GPG D95ED383
Systems Administrator, Python Developer, LPI / NCLA

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