PoE, Comcast Modems, and Service Outages

Wed Mar 30 18:08:27 UTC 2022

Thanks Jason—they are all are business connections. I know they can be
restarted through the business portal, but honestly the business portal is
terrible for large clients.
Not all our connections are listed under the same account due to something
with Comcast and the way "regions" and various services are split. i.e.
there doesn't appear to be any way of seeing EDI circuts, only cable
connections. We were basically told for all the cable connections that we
had to have multiple email addresses for the various groups (i.e.
it1 at example.tld could add accounts in one region, it2 at example.tld could
handle a different region, etc...)

In some cases a reboot will trigger a pull of the latest firmware, which
might include security fixes, performance improvements, and other changes.

Good to know...but there generally seems to be a culture in both the "home"
side and the premier side that Comcast modems *will* start having problems
if they are left up and running for more than ~1 month. Some people say
they need to be rebooted every 21 days, others say "three to four weeks",
etc...

My routers run FreeBSD and they get rebooted maybe once a year when there's
a security update that affects us. Granted, the Comcast modems are probably
some embedded Linux variant, but it seems odd to me that there's this
generally accepted idea that they just need to be rebooted every few weeks
to "clear stuff out". They aren't my grandmother's Windows PC.

High packet loss typically suggests an RF impairment of some type. I don’t
know how to explain the PoE comment but am happy to look at your connection
if you want to email me off-list.

I would suspect RF issues on the cable side as well. There's a very large
cell phone tower about 2 blocks away with about half a million antennas on
it.

As for the PoE issue, I'm not trying to get anyone canned. The tech was
professional and polite—just wrong. He was insistent enough that I started
to question my understanding of the PoE standard, my networking knowledge
and possibly my own sanity. 😉

Thanks for reaching out though. I really do appreciate how responsive
Comcast is—not just you and others on NANOG, but generally as a large
corporation as a whole. For ~40 connections I usually find myself reaching
out to the premier group once a week and they're polite, knowledgeable and
99% of the time 'hassle free'. 🙂

-A

On Wed Mar 30, 2022, 05:53 PM GMT, Livingood, Jason
<Jason_Livingood at comcast.com> wrote:

> I asked him to remotely reboot the modem because there was high packet
loss.

FWIW, as a customer (assuming residential), you can login to the website
and check for area outages/impairments at
https://www.xfinity.com/support/status-map. You can also use the Xfinity
app to remotely reboot your cable modem, run diagnostics/check for outages,
etc. See https://www.xfinity.com/support/articles/check-service-outage

> Both times I've talked with him, he noted the high packet loss, started
to reboot the modem, and then asked me point-blank if we had any PoE
switches on our network.

High packet loss typically suggests an RF impairment of some type. I don’t
know how to explain the PoE comment but am happy to look at your connection
if you want to email me off-list.

> I said "it's up and working fine, why would I reboot it?".

In some cases a reboot will trigger a pull of the latest firmware, which
might include security fixes, performance improvements, and other changes.

Jason
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