[VoiceOps] Cox cable "outages" and a solution

Carlos Alvarez caalvarez at gmail.com
Mon Mar 21 12:45:59 EDT 2016

We have always deployed our phones to only use our own DNS and SNTP
servers.  The phones only accept the IP and gateway from DHCP.  We found
out about the issues because customers' IT people were asking us why the
phones were working and "the internet" was not.  After stringing them along
on answers about voodoo and black magic, we figured it out.  I posted here
because not everyone doest things this way.

On Mon, Mar 21, 2016 at 9:39 AM, Lee Riemer <LRiemer at bestline.net> wrote:

> If you’ve deployed hard phones for these users, try configuring the phones
> to use your own DNS servers.
> *From:* VoiceOps [mailto:voiceops-bounces at voiceops.org] *On Behalf Of *Carlos
> Alvarez
> *Sent:* Saturday, March 19, 2016 11:49 AM
> *To:* voiceops at voiceops.org
> *Subject:* [VoiceOps] Cox cable "outages" and a solution
> I'm posting this info here because I know quite a few of us have BYOI
> customers and may be affected by this.  Cox users have been reporting a lot
> of outages lately in certain areas (it seems to cluster by whatever areas
> Cox is making changes in).  I found that when there is a supposed outage,
> the only thing that fails is DNS. You can still ping/trace/connect with an
> IP address. I looked at the router's DHCP-assigned info and found that it
> was seeing an IPv6 DNS as its primary, with the usual two IPv4 servers as
> secondary/tertiary. Oddly, this didn't seem to happen right away, but would
> happen after the router had been up for a few hours. My best guess at the
> root problem is that Cox isn't properly handling IPv6 yet, even though they
> are advertising it to the router.  Completely disabling IPv6 in the router
> fixes it.
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