[Outages-discussion] RoadRunner/Bright House cablemodem problems

[Jay Ashworth]

I can get you the details on models and such tomorrow, but the topo
is RF -> Cablemodem, Gig-E -> Fortigate 60D WAN1 port.  No other devices,
in production; I had things plugged into the other ports only for 
diagnosis.

That router has a /31 static configured on the wan port; the cablemodem
will hand out NATted DHCP addresses, but they're 172.16/12.

----- Original Message -----
> From: "Jeremy Chadwick" <jdc at koitsu.org>
> To: "Jay Ashworth" <jra at baylink.com>
> Cc: "outages-discussion" <outages-discussion at outages.org>
> Sent: Monday, September 16, 2013 5:16:09 PM
> Subject: Re: [Outages-discussion] RoadRunner/Bright House cablemodem problems
> On Mon, Sep 16, 2013 at 04:11:15PM -0400, Jay Ashworth wrote:
> > On a new install for a client, we're seeing that the cable modem
> > drops
> > out on us, and in a very interesting way.
> >
> > Every so randomly often, it apparently does an uncommanded reboot
> > (this
> > according to a guy who was logged into the CMTS looking at it one
> > time it
> > did so), and when it does, 2 connected devices see the ethernet drop
> > for 3-5
> > seconds, come back up for 15, then drop again for 3-5, and then go
> > back
> > to normal. I see this behavior logged exactly to the second on both
> > the
> > attached Fortigate router and my Linux laptop; we've replaced the
> > cable
> > modem and the ethernet cables coming out of it.
> >
> > Oddly, it only seems to happen when there's traffic on the link; I
> > haven't
> > seen a drop get logged when the link is idle (overnight/weekends).
> >
> > The cablemodem is a DOCSIS3, Motorola Surfboard Extreme (that's not
> > exact,
> > but I can provide a model number if anyone thinks it's critical).
> > Everything
> > in the cage is on a brand new 2000VA UPS.
> >
> > Anyone ever seen a cablemodem misbehave in this particularly
> > peculiar way
> > before?
> 
> I can probably help (I just spent nearly 5 months getting Comcast to
> deal with replacing some actual runs of cable between poles that were
> accepting interference -- in the end things were successful), but I
> need the following things:
> 
> - Exact model of Motorola modem (SBxxxx) you're using and its firmware
> *and* hardware version (visible via http://192.168.100.1/cmHelp.htm)
> - Whether DOCSIS 3.x is in use or not -- no, actually, i'll redact
> that
> and just request this: a screenshot or PDF of the /cmSignal.htm page
> - Same as before, but for /cmLogs.htm
> - A topology diagram of things (don't need IPs/etc., just general
> what's-connected-to-what) -- I'm mainly interested in the device which
> hooks up to your cable modem's Ethernet port. You mention "4 ports"
> (discussed with Frank) which is a device I haven't used before; I'm
> used to the consumer models which have 1 Ethernet port. Knowing
> what's connected (brand/device/driver-wise) to all those Ethernet
> ports would be of interest
> 
> If this turns out to be what my issue was (very hard to track down),
> I can give you a perl script that I wrote that polls the cable modem
> periodically and stores SNRs in CSV which you can graph using dygraphs
> (very very easy, I can include a working .html and relevant .js file).
> I can put up a demo for you online (with real data) if you want to see
> it first.
> 
> I do have a gut feeling about what the issue is, but a topology
> diagram
> would help to rule out that feeling.
> 
> --
> | Jeremy Chadwick jdc at koitsu.org |
> | UNIX Systems Administrator http://jdc.koitsu.org/ |
> | Making life hard for others since 1977. PGP 4BD6C0CB |

-- 
Jay R. Ashworth                  Baylink                       jra at baylink.com
Designer                     The Things I Think                       RFC 2100
Ashworth & Associates     http://baylink.pitas.com         2000 Land Rover DII
St Petersburg FL USA               #natog                      +1 727 647 1274