DHCPv6 Confirm in DOCSIS networks

[Tore Anderson]

* John Jason Brzozowski

> [jjmb] there are some other things we should discuss offline, perhaps
> with your provider that I imagine are of interest.  contact me at work
> if you wish to discuss.

I'll certainly take you up on this offer, thanks! My contact in Get (my
provider) is busy with non-IPv6 stuff in the next week though.

>     No preference values are being transmitted in the ADVERTISE messages.
>     Hmm. I've had my PD prefix change on me once already, and that's the
>     probably the reason. Unlike my laptop, my HGW (a ZyXEL P2812) sends
>     RELEASE once its WAN port goes down, and starts the DHCPv6 client state
>     machine from scratch (with SOLICIT) once it comes back up. So I guess
>     that would mean it's a coin's toss whether I get back the same prefix I
>     had before, or if I get the prefix offered by the other DHCPv6 server.
>     Which is rather problematic, as the ZyXEL doesn't handle LAN renumbering
>     very well, so I get left with stale and non-working addresses from the
>     old prefix on the hosts.
> 
> [jjmb] you should get your PD renewed, your operator may have to tweak
> some CNR settings.  CNR has great support for IPv6.  I worked with that
> team (include Bernie) over 6 years ago to  help put it there.

The problem is that my HGW will immediately forget all about the PD as
soon as you unplug the WAN port. I would imagine that this runs counter
to various RFCs, but that's how it behaves. So when I reconnect it to
the cable modem, it won't try to renew/confirm any previously received
IA_PD (or IA_NA for that matter), it starts the DHCPv6 client completely
from scratch. So if there's two DHCPv6 servers, offering two different
IAs, the chance of getting back my old prefix would be fifty-fifty,
right? (Assuming the Preference option isn't included in the ADVERTISE
messages, that is.)

>     Currently I only get only one ADVERTISE message though, so perhaps
>     they're working on improving this as we speak.
> 
> [jjmb] perhaps or they have a separate, single server for IPv6. 

They had two servers a couple of days ago, but now I see only one. So
perhaps they shut down one in order to implement the Preference option.
Or one crashed. No idea really. It's still at a early pilot stage so I
can imagine they feel free to change stuff around without notifying me. :-)

You can [un]subscribe from this list here:
http://lists.cluenet.de/mailman/listinfo/ipv6-ops

BR,
-- 
Tore Anderson
Redpill Linpro AS - http://www.redpill-linpro.com/