more on Your Cable Company -- powered by the guy with the extension cord

[David Farber <dave () farber net>]

Begin forwarded message:

From: Armando Stettner <aps () ieee org>
Date: August 12, 2006 3:19:11 PM EDT
To: dave () farber net
Cc: ip () v2 listbox com
Subject: Re: [IP] Your Cable Company -- powered by the guy with the  
extension cord

Dave,

For IP'ers if you wish.

The situation that Lauren came across is most unusual.  Most cable  
companies, bowing to competitive and/or local PUC regulatory  
pressures, provide both battery backup and generators throughout  
their infrastructure - even out at some remote polls.  Still, the  
subscribers' must have their VoIP cable modem powered.

One of the more important differences between phone services from  
traditional telephone company  vs. those from a cable company is how  
power is distributed.  The traditional phone company powers your  
plain old home phone (not wireless, etc.) from the wire (pairs)  
themselves.  Cable companies do not typically provide power down to  
the subscriber (although devices along trunk and feeders in the cable  
plant can be powered by in-line power devices).

So, if one has phone service from a cable company, your cable modem  
has to be powered for your phone service to work.  Many cable  
companies recognize this problem and supply cable modems supporting  
VoIP that include a small UPS.  Others actually power the VoIP cable  
modem (sometimes called an network interface unit or multimedia  
terminal adaptor) from 'cable' power using drop cable with additional  
conductors to carry the power.  It should be noted that the cable  
company's VoIP is somewhat different from those of Vonage and  
similar  providers, etc.  Vonage and others support SIP and are not  
associated with the subscriber's broadband supplier (cable company or  
telephone company's DSL).  The cable company's VoIP is usually based  
on CableLabs' PacketCable.  (Vonage, and I assume others, have neat  
feature where when the subscribers network device is not accessible,  
they will ring a designated phone number such as a cell phone, etc.)

As an aside, when I was involved with engineering VoIP for cable  
systems and advanced cable set top boxes, one commonly held belief/ 
statistic is that about 50% of US households had only wireless/ 
cordless phone instruments and, as such, were mostly out of luck when  
the electric service was out.

   armando



Begin forwarded message:

> From: David Farber <dave () farber net>
> Date: August 12, 2006 11:31:01 AM PDT
> To: ip () v2 listbox com
> Subject: [IP] Your Cable Company -- powered by the guy with the  
> extension cord
> Reply-To: dave () farber net
>
> Begin forwarded message:
>
> From: Lauren Weinstein <lauren () vortex com>
> Date: August 12, 2006 6:45:41 AM EDT
> To: dave () farber net
> Cc: lauren () vortex com
> Subject: Your Cable Company -- powered by the guy with the  
> extension cord
>
> Dave,
>
> Last night at around 2:15am (yup, everyone's just leaving the bars)
> my area had a widespread power failure when someone wrapped
> themselves around a main distribution line power pole (this is a
> Friday and Saturday night tradition of course).  While LADWP started
> on it pretty quickly, power was not restored for around seven
> hours.
>
> That long an outage is enough to expose one of the serious weak points
> in our telecom networks -- remotely situated batteries.  They don't
> last very long without external charging power, and we already know
> that microcell sites tend to go down quickly for this reason when
> power fails.
>
> Early this morning when I started walking the area to see the
> effects, I quickly found an unmarked white bucket truck with engine
> running, parked at a nearby corner, with an orange extension cord
> running from its open hood to the open cable backup power box on the
> nearby pole, containing what looked like about three gel cells.
>
> When I went over and talked to the friendly cable guy splicing wires
> on the back of his truck, he told me that he wasn't even trying to
> charge the batteries, all he could do was try to keep the system
> running from his truck until power was restored.
>
> Cable modems?  Cable VoIP?  Our whole world of modern cable telecom,
> dependent on a guy with an extension cord and an old bucket truck.
>
> I found it rather amusing, in a "sad commentary" sort of way.
>
> --Lauren--
> Lauren Weinstein
> lauren () vortex com or lauren () pfir org
> Tel: +1 (818) 225-2800
> http://www.pfir.org/lauren
> Co-Founder, PFIR
>    - People For Internet Responsibility - http://www.pfir.org
> Co-Founder, IOIC
>    - International Open Internet Coalition - http://www.ioic.net
> Moderator, PRIVACY Forum - http://www.vortex.com
> Member, ACM Committee on Computers and Public Policy
> Lauren's Blog: http://lauren.vortex.com
> DayThink: http://daythink.vortex.com


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