[TriLUG] cable modem caps locally (was: Re: Road Runner and Linux (was: replacing a hard drive))

[Ben Pitzer]

Well, the modem is unlikely to be the culprit in this instance.  The
more likely thing is that the hub site that you are now plugging into
may be due for upgrades, or perhaps a recombine.  Moving modems around,
even though they'll work, doesn't guarantee that you'll get the same
bandwidth.  TW and RR are constantly doing plant maintenance to adjust
for capacity, clean up signals, etc.  Sometimes cards in the CMTS can
start to go bad, and the signal will drop.  There are other factors as
well which will result in a lower SNR (signal to noise ratio), and cause
you to not see the same throughput.  Cable pirates have been known to
cause this.  Uncapping your modem will not only fail to resolve this
issue, if that is the case, it will also ensure that you will not be a
TWC/RR customer for much longer.  It's illegal, and it's theft of
service.  We do offer higher bandwidth teirs if you need them, under our
commercial services.  But we look poorly on residential customers who
consistently run at 80-90% of their individual bandwidth on a regular
basis, because it typically means that they are performing some function
which violates the AUP, such as running a warez server, sharing
bandwidth with other users (knowingly or not, via wireless, for
example), or illegally sharing copyrighted material (before the flames
start, while I don't like the RIAA or MPAA's methods, tactics, or logic,
the law is behind them, and sharing MP3s, movies, software, etc. via a
gnutella service such as Kazaa, Morpheus, or the like, or via Napster,
gnapster, OpenNap, or whatever else is illegal).  It might also mean
that you are running an open relay, or that you've been cracked, and
someone is using your machine for unpleasant things.

In any event, the cap is provided to the modem dynamically, via a TFTP'd
boot file.  Your modem gets the correct boot file from a TFTP server. 
It knows what file to get because the LDAP server tells it which one. 
If there is no record of that modem, then the modem is told to TFTP a
disabled boot file, which does not pass any traffic.  The modem still
has an IP and is routeable, but no CPE (customer premise equipment) will
be able to get an IP, or pass traffic.

One more big non-official-but-true-nonetheless warning:  MODIFYING OR
TAMPERING WITH YOUR DOCSIS BOOT FILE, OR DIRECTING YOUR MODEM TO LOAD A
CUSTOM BOOT FILE FROM A SOURCE OTHER THAN THE ROAD RUNNER SERVER IS
CONSIDERED THEFT OF SERVICE, AND IS PUNISHABLE BY LAW.  IN ADDITION TO
THE TERMINATION OF YOUR SERVICE, CRIMINAL CHARGES CAN BE BROUGHT AGAINST
YOU FOR PARTICIPATING IN SUCH ACTS.

In other words, don't do it.

Hope that helps.

Regards,
Ben Pitzer


On Wed, 2002-10-09 at 13:20, James Manning wrote:
> > [Mark Turner]
> > Incidentally, you are perfectly within your right to own your own cable 
> > modem. TW will knock a few bucks off your monthly bill, too.
> > 
> > I'm pretty sure that you first need to give them the modem's info before 
> > they will connect it to their network.
> 
> Incidentally, I just got TW cable modem service at my place yesterday
> and while I was used to 2Mbit (250KB/sec) at the old house, I'm only
> seeing around 800Kbit (100KB/sec) here.  I'm gonna setup a cron job to
> do some fetches on an hourly basis to see if that's just a contention
> thing, but it "feels" (since the speed stayed pretty much dead-on
> constant) like it's a cap being done at the cable modem itself.
> 
> Incidentally, the cable modem is this translucent green shark fin kind
> of thingy - a lot diff than the surfboard I had used at the old place.
> 
> 1) What caps are in place at the cable modem these days?
> 2) What other caps might be in place (protocol/physical limitations, too)
> 3) Would picking up one of the old surfboards and connecting it have
>    any chance of getting me back to the old 2Mbit/sec rates?
> 
> Ben? anyone?
> 
> Thanks!
> 
> James
> -- 
> James Manning <http://www.sublogic.com/james/>
> GPG Key fingerprint = B913 2FBD 14A9 CE18 B2B7  9C8E A0BF B026 EEBB F6E4
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