Begin forwarded message: From: Armando Stettner <aps@xxxxxxxx> Date: August 12, 2006 3:19:11 PM EDT To: dave@xxxxxxxxxx Cc: ip@xxxxxxxxxxxxxxSubject: 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@xxxxxxxxxx> Date: August 12, 2006 11:31:01 AM PDT To: ip@xxxxxxxxxxxxxxSubject: [IP] Your Cable Company -- powered by the guy with the extension cordReply-To: dave@xxxxxxxxxx Begin forwarded message: From: Lauren Weinstein <lauren@xxxxxxxxxx> Date: August 12, 2006 6:45:41 AM EDT To: dave@xxxxxxxxxx Cc: lauren@xxxxxxxxxxSubject: Your Cable Company -- powered by the guy with the extension cordDave, 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@xxxxxxxxxx or lauren@xxxxxxxx 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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