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IP Telephony Drives in Power over Ethernet
GuitarNeophyte writes "The Channel Register states that although the idea for Power Over Ethernet has been around for a long time, the stage may finally be set for it to become an essential factor in our technical lives. One of the main reasons is because of the emergence of ip telephony. 'Telephones need to work in an emergency including when there is a power failure. Traditional telephones do, but IP phones will only do so if there is an uninterrupted power supply (UPS). The only practical way of guaranteeing power supply to a large number of IP phones is PoE.' Will IP telephones bring in PoE?"
Troll?
I guess I should have writte POE in big, bold letters to make sure everyone got the joke.
Tim
That'll be great when there's a storm, and trees bring down the power lines.
I remember a while back there was an article on Slashdot about how PoE can become an universal power standard. While there are different plugs and voltages used around the world, PoE has a standard jack. Sure PoE is low powered but with miniaturization, many of our devices can be powered off of PoE. With VoIP driving the spread of PoE, I hope this will build momentum in making the prediction come true. Imagine going to another country and needing to bring just a CAT 5 cable instead of a power adapter.
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At my office we've already switched over to new Cisco VoIP phones, which are powered via the ethernet cable. There is an optional DC plug for a wall wart if it can't power up via the ethernet cable. On a related note, when I called my parents today my call was dropped because their VoIP connection was too busy. So I still don't entirely trust the technology to be reliable, especially in emergencies, not to mention power outages in rural areas where when the power goes out, the ISP provider's (cable company's) equipment also goes down. If you have VoIP, I suggest a cellphone as a backup. But if you have cellphone with a reasonable plan, do you even NEED VoIP?
Yeah, I've had a wireless phone for years, never a single problem during a blackout, it works fine. So tell me again why we need to reinvent the cell phone?
and what do you think will power those access points? oh right POE
Telephones need to work in an emergency including when there is a power failure. Traditional telephones do
The majority of phones today are cordless and practically none work without power.
I used to buy cordless phones that had a speaker on the base unit for this very reason, but alas, those also don't work anymore without power, on most modern phones.
With the proliferation of cordless telephones in the 80s and 90s, most people today don't even remember that a phone can work without power. And those that do probably don't even have a regular corded phone around the house anymore. I don't think telephone service during a power outage is important to that many people..
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No freaking kidding. The phones were about the only thing that survived Hurricane Ivan last September (in my neighborhood, at least). When Hurricane Dennis went through last week, we were once again power/cable/waterless, but the phone still worked.
So I fired up my generator, jacked the laptop into Earthlink dial-up, and was right back online.
I'm in no hurry at all to abandon traditional telephony. It works.
This is my post. There are many others like it. If you don't like what you read here, go try one of the others.
The standard seems to be around 220v @ 50 or 60hz AC. I'm not sure I want that kind of load on four twisted pair of cable (CAT5). Besides, being the RJ45 connection could be standard eithernet, what's to prevent your casual user from making a BIG mistake. Jokes aside, it could cause one's battery in a laptop to explode with the force of a stick of TNT.
For power ratings around the world, check out http://kropla.com/electric2.htm
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Even with PoE a few well placed and clearly marked land lines combined with near ubiquitous cell phones add an extra layer of insurance for 911 and for more mundane VoIP issues.
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WTF are you talking about? PoE as ratified by the IETF does a low voltage chat over the unused pairs to determine if the device needs power, the likelyhood of a device not needing power and randomly responding over the unused pair correctly to trigger power is essentially nill. Certain pre-standard PoE injectors (such as those shipped with certain Cisco/Aironet AP's) may cause damage when used on a port with other equipment attached, but anything which is compliant with the 802.3af standard should have an essentially zero percent chance of frying attached equipment.
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IP phones will only do so if there is an uninterrupted power supply (UPS). The only practical way of guaranteeing power supply to a large number of IP phones is PoE.'
Because POE doesn't require an UPS during a power failure? The Ethernet just keeps on working without power? And the power keeps working because the ethernet is working, right?
Or.... you have a big honkin' UPS in the basement that powers the ethernet and the POE?
Modern FTTP installations require a significant battery to keep your fiber-transported dialtone working during an outage. Now you add some central UPS to keep you IP telephony working? At some point, don't you just start outfitting houses with battery arrays and generators?
So you take the industrial solution already used by the telco and put it in a small package for the individual home.
Personally I would have used cheap non PoE edge switches and installed a separate PoE injection patch panel.
My own questions about IP for interactive media go at least as far back as the early '90s and the first proposals for RSVP, which introduced a lot of religious debate in the networking community, including what seemed to me to be a lot of circular logic, e.g:
Q."Why do you want to retrofit IP for something it was never designed to do (realtime interactive media)?
A. "Because ATM is too expensive and wastes too much bandwidth."
Q. "How do you plan to upgrade IP then?
A. "By making IP equipment much more expensive, and wasting bandwidth to to prevent dropouts."
I know this grossly oversimplifies the issue, but I never seemed to grasp the theory behind IP as the solution. It always seemed like bandaids on top of bandaids, and no matter how many bandaids are cobbled onto IP, it never seems to be able to deliver the reliability of ATM. Now with cell networks and some broadband providers using ATM, maybe the pendulum is swinging back the other way.
But then again my viewpoint is dated because I've been out of the field for a few years, so any updates to my undestanding would be appreciated.