[ale] OT: What the hell is XSS in Comcast land?

JD jdp at algoloma.com
Mon Aug 12 11:13:14 EDT 2013


On 08/12/2013 09:49 AM, Ron Frazier (ALE) wrote:
> That leads to an interesting question.  I wonder how the telephony traffic
> gets mixed in and what ip it has when it exits.  I wonder if it even uses ip
> to get to the comcast data center.

I don't know what Comcast does, but I know how I'd architect this.
Voice is on a guaranteed bandwidth IP channel and provided with the highest QoS
possible on the network. It uses a different subnet than normal IP traffic and
it is probably tagged to a specific VLAN to get higher QoS across the entire
Comcast WAN.  DOCSIS 3 has some great features that DOCSIS 2 and lower didn't
support. v3 makes bandwidth management much easier for cable network providers -
dynamic QAM hops are the coolest - well, with more channel bonding support too
and IPv6 support. DOCSISv2 doesn't do those things. As long as anyone uses a v2
device, it makes taking advantage of the v3 capabilities much harder.

I'm positive that U-Verse does something very similar. Bandwidth is reserved on
different DSL frequencies just for VoIP, just for TV, and then ISP traffic gets
whatever is left for that specific run. It all uses IP from the main u-verse box.

The goal for all the service providers is that any extra service you
specifically think of as "Comcast" or "TPC" work as well as possible. With
internet, they can blame upstream providers for the experience sucking. Hard to
shift blame for TV or phone service that are 100% internal services, right?

I had Comcast phone service for a year or so. It had issues:
* Service outages almost every Thursday afternoon at the same time for an hour.
TV and internet still worked, just VoIP didn't. An hour outage wouldn't normally
be an issue, except this happened at the specific time when a weekly business
meeting was scheduled.
* Couldn't call certain numbers on TW and other VoIP services.
* Call quality sucked about 20% of the time. I think that was related to the
very long run from the curb to my demarcation point. Even with huge coax, they
couldn't get a signal that met specs in the room where I wanted service. It was
close enough that it worked most of the time, so I left it.

When the 12 months of cheap phone service was up and comcast had re-run new,
larger, coax to my home, I canceled the VoIP. Bought a $5/month wholesale plan
and never looked back.  About a year later, I switch the internet from
residential to business - got another new coax - needed 2 lines for some reason
- residential TV can't share business lines, I guess.  About 6 months later,
killed the residential TV completely. OTA I receive about 70 TV channels using a
home-built $20 DB4 antenna.

It seems that the trick to getting new coax run for free is to add a new service
and if there is **any** issue at all, have them fix it in the first 30-60 days.
If they can't, cancel.

On the SMC business class modem - Comcast owns it - I plug my routers into it
with the static IPs configured.  If I attach a non-static IP device, the SMC
provides a 10.1.x.x IP automatically.  According to the tier 3 guy, Comcast
changes the root password on these routers daily to ensure that fired router
configuration techs can't do anything bad 1 day later.  Setting a local-admin
password on the router has never worked correctly. I won't bore you, but after
an hour with a teir3 person, we couldn't solve it. They refused to replace it
without a truck roll for $90.  I treat that router as a hostile network now.


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