DHCPv6 Confirm in DOCSIS networks

[Bernie Volz (volz)]

In the pcap files you provided there was no server preference option ... Configuring that can help as the client should always prefer the same server (except if it is down when Solicit received).

That file also only showed IA_NA request; no IA_PD.

Sent from my iPad

On May 19, 2012, at 5:57 AM, "Tore Anderson" <tore.anderson at redpill-linpro.com> wrote:

> Hi,
> 
> * John Jason Brzozowski
> 
>> Tore your CMTS could be dropping the CONFIRM message. I know of only >
> one CMTS that drops this type of message.  The Cisco 10K.
> 
> The CMTS has a Cisco MAC address, so it seems likely that this is the
> reason why it doesn't work. Thanks - I'll discuss this with my provider.
> 
>> The operator probably has two separate DHCPv6 servers running for
>> redundancy.  As such, and in the absence of DHCPv6 failover support,
>> both servers will send an ADVERTISE.  Does one server have a higher
>> preference value than the other?
> 
> 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.
> 
> Currently I only get only one ADVERTISE message though, so perhaps
> they're working on improving this as we speak.
> 
> BTW, I found draft-ietf-dhc-dhcpv6-redundancy-consider-02, very useful
> work that I'll pass along to my provider, thanks!
> 
> Best regards,
> -- 
> Tore Anderson
> Redpill Linpro AS - http://www.redpill-linpro.com/