[ale] Cable modem recommendation

[Michael H. Warfield]

On Mon, 2012-04-02 at 10:31 -0400, mike at trausch.us wrote:
> On 04/02/2012 10:08 AM, Michael H. Warfield wrote:
> > On Mon, 2012-04-02 at 09:47 -0400, mike at trausch.us wrote:
> >> On 04/02/2012 08:33 AM, Lightner, Jeff wrote:
> >>> Does anyone know if there is a special device required for Comcast
> >>> telephone and if so would they be charging an extra monthly fee and
> >>> if so if one can buy one rather than rent as they can with cable
> >>> modem?
> > 
> >> It is indeed some form of VoIP.  That said, just like many of the VoIP
> >> providers, they typically require that you use an MTA that is provided
> >> by them and therefore provisioned through them.
> > 
> > Well, there's some variation in the degree of "required".  AT&T Uverse
> > very strongly wants you to use their RG (Residential Gateway) to provide
> > HPNA network over coax, video over IP, phone VoIP, wired networking and
> > wireless networking.  But their RG is a serious POS.  It goes dain
> > bramaged every once in a while requiring a reset, sometimes loses
> > setting like static mappings, has a dhcp server that's total junk, and
> > doesn't support a lot of things I would personally consider mandatory in
> > a modern device.  (The set top boxes - STBs - even run Windows ME for
> > crying out loud - stone knives and bearskins.)  You CAN replace it with
> > one you buy off the shelf I read on article on a person's experience
> > getting it up and running.  It wasn't a pleasant experience since the
> > AT&T people are not familiar with provisioning the devices and are not
> > encouraged or encouraging to pursue it.  But they will, if forced.  He
> > got his running.  It can be done.  It likely won't be easy.

> DSL networks are very different from cable networks.

Oh, I'm well aware of how they both work.

> In DSL networks, authentication occurs using your personal credentials,
> usually over some form of PPP (PPPoE is what AT&T uses, if memory
> serves).

That is correct.

> It is a PITA, but it is possible to do absolutely anything you
> want; they cannot make you use a particular device, all they can say is
> that your device must not interfere with the telco's network.

> OTOH, cable networks use MAC addresses for authentication (wonderful,
> isn't it?).  A residential Comcast customer that has no services other
> than Internet (or Internet and TV, the important thing here being that
> they do not have the Voice package) can go out to the store, pick up a
> cable modem, install it, and then call Comcast.  Comcast will require
> that you read the MAC address of the device, and then they will
> "provision" it, which involves sending a configuration file to your
> local node or hub or whatever it is on their network that your modem
> actually talks to.  Then, the cable modem will be able to grab a
> configuration file and you'll be out of the walled garden.

Yeah, I have a couple of DOCSIS 2 cable modems laying around from the
last time I was with Comcast.  I've had my own cable and DSL modems for
a very long time.  Even had a couple of the Comcast ones tftp booting
from my server to play with them.  :-P  Actually, I might have given one
of those to my son Scott, since he's still with Comcast.

AFA the link layer authentication goes, that's one thing.  In general,
in principle, the VoIP is at least semi-independent.

The cable companies have to walk a fine line or run a foul of the FCC
regulations in this area.  At one point the FCC was even requiring cable
companies support "cable cards" for consumer purchased equipment but
that turned into an abject failure as nobody bought them.  The biggest
stick in the mud with cable companies is encrypted content such as
premium TV channels, movies, and view on demand.  DTV channels sort of
complicated that a bit but there were cable TV tuner / capture cards
that worked really well with the Comcast channels if they weren't
encrypted.  That's what the cable cards were SUPPOSE to address by
allowing consumers to provide their own STBs while still allowing the
cable companies control over their premium content.  While cable cards
are still a failure, there's still teeth in some of those FCC regs
mandating some level of support for consumer purchased equipment, which
is really where the standardized DOCSIS modems and devices have come in,
which Comcast does support.

> Now, I have been told that the business class side works a little
> differently; they use some form of PKI to provide authentication for the
> routed tunnel that you obtain through them.

Yeah, I have never dug deeply into that but, talking with a couple of
people who have, there's some sort of tunneling involved in there.

> In the case of AT&T and having a routed block, they will just send your
> routed block over your PPPoE session, once established.

Correct.

> I have no clue how to determine what my current cable modem is doing,
> because I haven't the ability to capture or monitor the coax side of the
> network.  If I could only do that...

I used to be able to do that (in fact, that's what the second DOCSIS
modem was for).  Never really got anything useful out if it and I never
played around with it on the RF level.

There's a couple of styles of adapters out there too which allow you to
piggyback ethernet over 75 ohm coax together with cable.  AT&T settled
in on HPNA which is NOT compatible with a coexisting cable TV signal but
they run everything over IP so they don't need it.  HPNA boasts 200Mb
over standard grade 75 ohm CATV coax (RG-59) with upgraded connectors.
All the AT&T Uverse STBs are actually HPNA bridges and you can bridge
twisted pair off the back of them down the coax runs.  The MoCA adapters
will actually interface Cat 5/5e/6 to your cable TV cable and are
suppose to be compatible with the Comcast signal (they occupy different
parts of the spectrum).  I think there's a third standard which is also
suppose to be compatible with standard broadband CATV but I'm not
familiar with it.
 
> >> I don't know what Comcast's rules are; I'm not sure if they allow you to
> >> swap out for your own dedicated devices or not.  I know that many other
> >> providers do not, because of the recent requirements that they provide
> >> certain services in the same way as landlines (e.g., 911 service).
> >> Therefore, they likely require that you use their own device so that
> >> they can control the configuration and such.
> > 
> >> The advantage to Comcast's MTAs (which are built-in to the cable modem
> >> itself) is that they have a battery back-up contained in the box, too.
> >> This makes them bigger and heavier, of course, but it means that during
> >> short power outages, you still have telephone service.
> > 
> > The AT&T unit has an external battery backup that includes it's DC
> > supply.  I would consider that a plus to having a built in one.  As most
> > of us know all too well, those gel cells go bad after a few years and
> > are worthless.  Then you replace the battery or the UPS or the device.
> > I would much MUCH rather have a separate UPS that alerts you when the
> > battery is failing or needs replacement.  The one on the AT&T unit isn't
> > anything to brag about but it doesn't have anything serious to carry.
> > If it died, they could easily replace it without swapping my whole RG or
> > ripping it apart to replace.
> 
> Agreed.
> 
> All-in-one devices are horrible.  Evil.
> 
> The current cable modem that I have is also a router/gigabit switch.  I
> cannot disable most of its functionality, and I can't do complex things
> with my address space, because this thing sucks so horribly.  If only I
> had control of my own IPv4 network... oh, well, that's what IPv6 is for!
>  :-)
> 
> 	--- Mike

Mike
-- 
Michael H. Warfield (AI4NB) | (770) 985-6132 |  mhw at WittsEnd.com
   /\/\|=mhw=|\/\/          | (678) 463-0932 |  http://www.wittsend.com/mhw/
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