[169310] in North American Network Operators' Group
Re: comcast business service
daemon@ATHENA.MIT.EDU (Dan Shoop)
Thu Feb 20 16:15:12 2014
From: Dan Shoop <shoop@iwiring.net>
In-Reply-To: <CAH_OBidPuZJ05RNC-UdWnD4oq-hLRPtvKCfdZhMSss5Bmn5zFA@mail.gmail.com>
Date: Thu, 20 Feb 2014 16:14:12 -0500
To: Nanog <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Feb 20, 2014, at 4:08 AM, shawn wilson <ag4ve.us@gmail.com> wrote:
> A while ago I got Comcast's business service. Semi-idle connections
> are get dropped (I haven't really diagnosed this - I just no that it
> isn't the client or server but some network in between). However the
> second and most obvious issue is that intermittently, the service will
> grind to a halt:
> --- 8.8.8.8 ping statistics ---
> 37 packets transmitted, 34 received, 8% packet loss, time 36263ms
> rtt min/avg/max/mdev =3D 398.821/5989.160/14407.055/3808.068 ms, pipe =
15
>=20
> After a modem reboot, it goes normal:
> --- 8.8.8.8 ping statistics ---
> 4 packets transmitted, 4 received, 0% packet loss, time 3003ms
> rtt min/avg/max/mdev =3D 23.181/23.920/24.298/0.474 ms
>=20
> This seems to happen about once or twice a day. I can't attribute it
> to any type of traffic or number of connections. All of the rest of
> the network equipment is the same and the behavior persists when a
> computer is plugged directly into the modem. I called Comcast and they
> said they didn't see anything even when I was experiencing ridiculous
> ping times. I tend to think it's an issue with the 'modem' but I'm not
> sure what the issue might be or how to reproduce it when asked to if I
> tell them to look at it.
I=92ve seen this happen before with various cable ISPs. I=92d concur =
with the poster suggesting intermittent noise on the cable segment as a =
likely culprit. Also if you have a cable modem that binds multiple =
channels for higher bandwidth this can also be problematic, especially =
with the noise. Signals will look good to the NOC but it=92s not the =
signal =93level" that=92s the issue it=92s the signal to noise level. =
Noise has to be measured locally and techs don=92t always check SNL.=20
Also check to see if the packets aren=92t actually being dropped but =
just taking longer than ping is looking for. Also check for out of =
sequence packets returned. These can indicate flapping of a bonded =
circuit or the bonded circuit experiencing noise. Try seeing if you =
disconnect everything and get a straight run to the demarc, with a know =
and tested out good cable, if the problem doesn=92t ever occur. This =
could indicate noise on the cable in your premise. But I=92ve =
experienced this same problem with noise coming through the demarc. I=92ve=
also seen levels too hot beyond the demarc causing similar problems =
too.=20
HTH.
-d=20
-----
Dan Shoop
shoop@iwiring.net
1-646-402-5293 (GoogleVoice)
