Slashdot is powered by your submissions, so send in your scoop

 


Forgot your password?
Close
typodupeerror
×
Networking Communications Power Hardware

IP Telephony Drives in Power over Ethernet 278

Posted by timothy from the but-it's-not-wireless dept.
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?"
This discussion has been archived. No new comments can be posted.

IP Telephony Drives in Power over Ethernet More

IP Telephony Drives in Power over Ethernet

Comments Filter:
  • I work for a school system in Maryland (Charles County) and we're implementing system-wide IP telephony at all 30-something of our schools (20 elementary, 7 middle, 7 high, plus several education centers and other facilities.) All our IP phones use PoE, so half the ports in each school are PoE capable.

    BTW, First Post.

  • No 911? Quote the VOIP reseller... (Score:5, Funny)

    by TimTheFoolMan ( 656432 ) on Tuesday July 19, 2005 @09:23PM (#13109640) Homepage Journal
    ...nevermore... nevermore....

    Tim

  • Ethernet over Power? (Score:5, Funny)

    by GreatRedShark ( 880833 ) on Tuesday July 19, 2005 @09:26PM (#13109655)
    Apparently, my cousin has Ethernet over Power, that was installed by The Internet Service Guy...

    It would be interesting to see what happens if you ran Ethernet over Power on a system powered by Power over Ethernet... who would win? an epic battle, to be sure! ...or maybe they would cancel each other out, and you'd just get regular ethernet? ...or maybe it would be like a divide-by-zero, and your NIC would explode? :P

  • Useful (Score:3, Insightful)

    by Arghdee ( 813921 ) * on Tuesday July 19, 2005 @09:28PM (#13109668)
    That'll be great when there's a storm, and trees bring down the power lines.
  • So we get power over IP. How would that have helped any of, say, Broadvoice's customers in May?

    They had a major meltdown that lasted weeks for some of their customers.

    And they're just one example. All VOIP providers have had significant problems at one point or another.

  • Yes, IPT will bring PoE, but it won't be good for much other than powering phones and WiFi AP's. You can only put a few watts on each switch port, or you end up with a switch that's more of a heater than anything else.
    • iirc, it's 15.8watts per port, that's plenty of power for a lot of apps. maybe even for a low power pc with a small LCD screen.
      • Cisco's IP phones [cisco.com] can be powered by PoE, and they have giant displays on the front. We've been using them for a couple of years now. PoE for VoIP phones is nothing new.
      • You only get that wattage on a small numbers of ports. On all the switches I know of, you are limited to 24 ports at full power. Most of the phones only use about 4W.
        • you might be right, i have not had a need to check for switches with more ports than 24. mines were for a wireless network dispersed over a large area
        • Cisco's has a new 6509E chassis in the Catalyst line. It's main new feature? Power supplies at 6KW and 9KW capacities. You can get high density PoE. You'll pay for it. But it's available. Even a current 6509 with 2500W supplies will power quite a few phones.
        • A cisco 6509-E chassis can supply ~1,000 devices with the full 350mA input power @ 42V described in the 802.3af spec. In other words you can fully populate the chassis with 8x96 port blades and it will provide full power to all of them. Info obtained from here [cisco.com] which also has some useufull primer info on how 802.3af works as well a cisco pre-spec PoE.
          • Hmm, hate to reply to myself but Cisco says a max of 571 devices can be supported by dual 6KVA power supplies in the 6509-E, not sure where the descrepency between the numbers comes in. Still that's 72 ports per blade, which means you can fully populate the chassis with 48 port blades.

  • This does not necessarily follow. (Score:5, Interesting)

    by MindNumbingOblivion ( 668443 ) on Tuesday July 19, 2005 @09:31PM (#13109688)
    If we lived in a world without cell phones, I would say that yes, this would be a likely outcome. However, I live in a college town, where I'd say 9/10 people have a cell phone as their primary means of telecommunication. The attitude toward a land line is that it's for old people and businesses.

    I'd say that we will eventually have PoE, but I don't think it will be a necessary consequence of VoIP or telephony. I have VoIP, but I use it exclusively for the three hours a day I work as a call desk support monkey for my company. If I had an emergency, I have my cell phone on me as well.

    This is something I've wondered about a lot: how many slashdotters out there use VoIP as their primary telecommunications resource? How many would use telephony once x gets improved?

    • I'm one of those people who doesn't like cell phones. My land-line is basically already for emergencies only. I'm just as quick to use VoIP as I am the land line.

      So I'm one of those people who would gladly ditch the land-line in favor of VoIP once [x] gets improved, where [x] in my case is reliability. VoIP depends on (a) Internet and (b) the power grid, neither of which are near the reliability of POTS.

      Even so, I'm still pretty close to ditching the land-line in favor of Vonage. Unfortunately I think it'
      • In my experience (Central and North Texas, Sprint and T-Mobile,) mobile phone time is getting more expensive, not cheaper. The price points may not go up, but the # of minutes you get per price point has definitely gone down. I used to be able to get twice as many minutes per dollar than I presently can, if not more.

        Vonage, on the other hand, is a mere $25.00 (plus various taxes and regulatory fees, of course) for unlimited domestic calling. Plus, all the bells and whistles (that POTS providers charge a
    • how many slashdotters out there use VoIP as their primary telecommunications resource?
      I do. It's fairly reliable, but I wouldn't recommend it if you can't stomach the thought of losing dialtone occasionally.

      Personally I don't see reliability as that big a deal, so long as outages are relatively short. I don't worry about being away from the phone when I go to the store (no cellphone), so why should I worry about the occasional outage when I'm home?

  • I imagine we'll be seeing plenty of useless (but pretty) little blinkinlites and other silly gadgets built on RJ45 plugs, for keeping the dust out of unused router ports.

  • Deeper Implications (Score:5, Insightful)

    by Comatose51 ( 687974 ) on Tuesday July 19, 2005 @09:34PM (#13109709) Homepage
    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.

    • Re: (Score:3, Insightful)

      by account_deleted ( 4530225 )
      Comment removed based on user account deletion
      • You can't put that much voltage on a cable without having to redesign everything to comply with various electrical, building and safety codes. Low voltage and limited energy wiring, like that used for most computer networks, doesn't have to meet the same standards as wiring used for power distribution, which has the potential to start fires and kill people.
      • Besides, being the RJ45 connection could be standard eithernet, what's to prevent your casual user from making a BIG mistake.

        PoE is smart enough not to send the juice down the wire until the PHYS layer handshaking has determined that the other end is PoE-compatible.
    • My refrigerator has Internet, but my ice cream keeps melting.
    • The problem with PoE is that its -48V which is difficult to make unless your a phone company. Look at a typical PoE ethernet switch's power supply vs the lower voltage redundant ones and you'll see a huge difference in size and weight even though they are rated at the same power. 48V plug packs cost a fortune compared to the 5 and 12V versions as well.

      I'm thinking home and small business products won't be using ieee 802.1af ever and someone somewhere will come up with a different standard that fits that
  • WTF ?

    Power over Ethernet ?

    Broadband over power ?

    Has the world really gone topsy turvy ?
  • IP telephony drives PoE? Next they'll say that SUVs drive the oil industry.
  • 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 compan

  • I like it (Score:3, Informative)

    by PktLoss ( 647983 ) on Tuesday July 19, 2005 @09:50PM (#13109808) Homepage Journal
    I worked for a large company, during my time there we made the switch to VOIP, with the nice Cisco phones. The whole deal was set up with POE to all the phones, which was great for a couple reasons: Power outages we could still use the phone (as mentioned in the article), one fewer cord on our desk (no power cord), one less stolen slot on the power bar.

    The server room manager guy was a big fan of this system because it allowed him to reduce the number of UPS protected outlets outside of the server room (some models of the desk phones used at the help desk required their own power supply), and since it was now his problem a boost to his budget.

    Something I would /LOVE/ to see is POE being used on the desktop to maintain power to your RAM during a power outage. Obviously there is a chain of things that would need to support this in order for it to work, but on an enterprise level I think it sounds like a good investment. Once the power is restored everyone's machine turns on to it's previous state.
    • That probably isn't as easy as you might think at first, because while you'll retain the contents of RAM, you'll lose all hardware and processor state information.

      Or did I miss something?

      • A computer system can be designed to recover from a power failure. DEC used to do it on their minicomputers. The problem is that it has to be designed into the hardware, operating system and device drivers. The power supply can generate a power failure interrupt which allows the CPU to save its state in non-volatile storage and prepare for shutdown. I'm not aware of any modern systems that support power failure recovery.
        • That was my point, really. I can guarantee that on power failure a modern desktop PC couldn't recover if you gave it a roadmap. What they could do -- and what I think you're getting at -- is stick a small battery in the thing and when a power failure interrupt is raised, it calls a temporary system halt, shifts the RAM over to some other kind of power supply (or writes it to disk if it can), and saves all the state data. When power is restored, the system comes back up, the OS restores the application and h
  • We've got to call those fighters back!

  • Very likely (Score:2, Informative)

    by Microlith ( 54737 )
    My office just completed moving to a new office building, and one of the things planned from the beginning was VoIP phones.

    For VoIP phones to be useful in any way they had to be no more intrusive than a regular phone, but provide benefits. Power over Ethernet keeps the requirements for the phone down to a single CAT-5e cable, and a capable backend switch (we ended up going with an end-to-end Cisco solution for both phones and general network switching, which has worked out perfectly.) That and the system p
  • Reading the article indicates that a UPS is still required at the switch.

    What concerns me is if the FCC makes a ruling to the effect of "all VoIP solutions must continue to operate (to provide emergency services) during a power outage."

    Will this force all of the moms-and-pops who are running VoIP on their home computer to buy and install a UPS before they'll be allowed to connect to a VoIP service provider?
    • Will this force all of the moms-and-pops who are running VoIP on their home computer to buy and install a UPS before they'll be allowed to connect to a VoIP service provider?

      Might do, and might even ensure that new solutions coming onto the market take this into account. When VoIP first came out most people were thinking about the routine usage. Now that it is becoming more widespread people are realising some of the realworld issues and are now having to deal with it

      VoIP are now being told that they n
  • We recently implemented a medium size lot at our shop...around 160 IP phones.

    One thing that's really annoying is the 'bridging' factor in the phones. Seems most people freak at the cost of needing twice the Ethernet switch (not to mention if a large number of catV runs are required), so these phones bridge the connection from the PC.

    In our phones, when you bounce the phone you bounce the network connection to the PC due to this bridging approach. Not fun when you have many folks working on open file

  • internet vs phone line (Score:4, Informative)

    by airjrdn ( 681898 ) on Tuesday July 19, 2005 @09:59PM (#13109854) Homepage
    My phone line has rarely gone down if ever. I can't come close to saying that about my internet connections, cable or DSL. The fact that we have two small children means when I pick up that phone in an emergency, I want it to work. I don't want to be mucking around rebooting computers and routers. That's why I've stayed away from VOIP over my existing internet connection.

    Any thoughts on the reliability of this? Will VOIP ever be as solid as good old copper? I mean, you have issues (DDOS) with VOIP you just don't have with traditional PSTN service.

    • Re:internet vs phone line (Score:5, Insightful)

      by kitzilla ( 266382 ) <paperfrogNO@SPAMgmail.com> on Tuesday July 19, 2005 @10:12PM (#13109943) Homepage Journal
      > My phone line has rarely gone down if ever. I can't come close to saying that about my internet connections, cable or DSL. The fact that we have two small children means when I pick up that phone in an emergency, I want it to work.

      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.

    • Cell phone. Even if you don't have a plan, if the cell phone has power it is supposed to be able to call 911 (provided it isn't totally obsolete!). Find a cell phone from a provider that you know works in your area, buy a car-charging unit (12 volt adaptor) for it and you are almost certain to be able to call 911 in all situations where 911 is likely to be able to help you.

      Make sure to test everything first. I've never had a 911 operator complain when I called in and said 'Just verifying my line, thank yo
    • VOIP can be reliable, but it takes money and real engineering. It also takes a change in attitude, from "how cheap is it, how fast is it, and when can we ship?", to "how can it be broken and how do we prevent it from happening?". Although the Bell System is no more, they knew a lot about reliability and how to design fault-tolerant systems. I'm afraid that the same bean-counters that think that cheaper is always better will decide that 95% availability is good enough for VOIP, and if you are having a heart
    • My phone line has rarely gone down if ever. I can't come close to saying that about my internet connections, cable or DSL.

      Obviously you don't live in the UK. Around here, BT go to great lengths to ensure that telephone service attains the same degree of unreliability as everything else. If necessary they will employ people to come around to your house and put a spade through your telephone line.

      I mean, you have issues (DDOS) with VOIP you just don't have with traditional PSTN service.

      Uhh, did you just

  • Power from a wall outlet ... how exciting (Score:4, Funny)

    by nicodaemos ( 454358 ) on Tuesday July 19, 2005 @10:00PM (#13109860) Homepage Journal
    Bah, I can't wait for POWF - Power Over WiFi. Now that would be pretty darn cool!
  • ...this still would have some holes. Is the cable company going to also UPS the distribution point where it splits out? Around KY, the cable goes out before the power (most of the time), so you'd lose your IP over cable, and PoE wouldn't help unless all the communication points were similarly UPS'd.

    Tim

  • Traditional telephones do? (Score:5, Insightful)

    by slashdot.org ( 321932 ) on Tuesday July 19, 2005 @10:04PM (#13109880) Homepage Journal
    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.

  • Cordless telephones (Score:2, Insightful)

    by uofitorn ( 804157 )
    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..
  • Am I missing something, or does this not actually make any difference? You'd still have to have a UPS for your hub and your Cable/DSL modem, it just means your IP phone could be somewhere else in the house. Now if we had a PoE connection from the phone company or something, that would be different, but that 100MBps ethernet drop from SBC hasn't been installed yet.
  • PoE is nice, but it's expensive and a lot of customers don't like the idea of trashing their existing switches (yes, you can get injectors, no, it's not always that simple).

    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.

  • Will IP telephones bring in PoE?

    I use Comcast's Digital Phone service, and they used to have a box inside the house with a 6 AH gel-cel battery to run it in case of power failure. Well, I moved (only about 10 miles away) last year, and went back to Comcast for my phone service. Now they have a separate infrastucture built out for the phone system with its own power supply (90 VDC on the lines, I was told) so no battery box inside the house. Supposedly it's independent of the lines used for TV and broadba
  • That is, assuming that people want to use hardware handsets for VoIP.

    Next question?

  • Not just Phones (Score:5, Informative)

    by jonbrewer ( 11894 ) * on Tuesday July 19, 2005 @10:52PM (#13110211) Homepage
    PoE (802.3af [networkworld.com]) is incredibly useful in for business deployments of video cameras and wifi access points, not to mention mini-switches and outdoor wireless bridge equipment. You can even power a laser link [lightpointe.com] with PoE. It makes life easier for those averse to paying out huge amounts of cash to have an electrician come in and put in new outlets. I've been playing with PoE splitters recently to power non PoE gear at 5 & 12V DC - the splitters are $35 ea and are switchable between voltages.
  • We have an extremely large VoIP installation with all of our phones PoE... one thing we found out early on is that just about every PoE capable switch we looked at could not provide enough power to run all ports supporting Class III devices. A 48 port switch realistically could only support 30 or so devices, and that was with some super new higher wattage power supplies. That made our finance people see red as we kept asking for more and more PoE switches, and having to tell them that 18 ports per switch ar
  • Smart way to link to your own website with the UPS link.

    Not that there's anything wrong with that!

  • Home power plants (Score:2, Insightful)

    by Anonymous Coward
    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-tran

  • POE & Asterisk (Score:3, Interesting)

    by kfstark ( 50638 ) on Wednesday July 20, 2005 @12:59AM (#13110802) Homepage
    When I bought my new house, I had everything rewired including Networking and Phone (CAT5). Since I had already been using asterisk in the previous house, I installed it at the new house and have IP phones exclusively around the house (except for the wife's portable).


    I wanted to make sure that the phones stayed up at all times, so I bout a decent UPS for the wiring/server rack, installed netgear POE switches ($119 for 4port POE, 4port non-POE) and connected up all of the IP phones (polycom IP-500 and sipura 841). Since the cost of the POE switch was so low, I decided to do it this way for the comfort of being able to dial 911 at any time in any room.


    Yes, it is overkill for the home, but I like it and my phones have stayed up all of the time. Several of the offices I work for use centrex and there phones are plugged into normal power. They have had several outages since the installations 3-4 months ago.



    --Keith

  • My ISP (Charter) offers a $40/mo phone connection. Why is it worth more than Vonage's $25/mo service? According to the phone rep , because it includes a UPS so it works when the power goes out. Must be a heck of a UPS for $15/mo.

Slashdot Top Deals

Understanding is always the understanding of a smaller problem in relation to a bigger problem. -- P.D. Ouspensky

Close