Power over Ethernet Environmental Requirements
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Posted by on June 28, 2005, 3:20 am
Please log in for more thread options Hi all, Voice over IP (VoIP) is a technology being considered where I work (a University). We have a very large network with Cat5 outlets for data and voice, but the voice is patched back to a regular telephone system. It would be nice to be able to connect all Cat5 outlets into an PoE-capable Ethernet switch, then simply configure each port to the voice or data VLAN. However, there are some issues that I'd like your opinions on. If a typical wiring closet has 192 outlets (and our network has LOTS of closets), and these are all patched into a PoE switch stack, then that equates to about 6KW of power requirements (rough figures from various sites). Does this mean - I need to route a major power supply to the wiring closet? - I need a colossal UPS to provide a decent amount of runtime? (By the way, regular phone systems are protected by UPSes. Anyone know how long they are meant to run in the UK? I'm assuming there's some kind of regulation) - That much power is going to generate a lot of heat. Do I need air conditioning, which itself must be protected by the UPS? - That much power represents a fire risk(?) - do I need a fire suppression system? Suddenly a humble wiring closet needs the kind of very expensive environment previously reserved for server rooms. Any opinions greatly appreciated. Kind regards, Anwar | ||||||||||||||||
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Posted by James Knott on June 28, 2005, 10:57 am
Please log in for more thread options amahmood5@uclan.ac.uk wrote: Take a step back and look at things a bit clearer. That "6 KW" is a bit higher than the maximum amount of power permitted under the spec. You have to determine how many ports will be connected to a PoE device and also how much power each requires. Once you've done that, you'll have a better idea of power requirements. Incidentally, to give you an idea for comparison. I used to do planning for a large telecommunications company. In my office, there were over 2000 bays of equipment. The total 48V plant ran about 7,000 amps or 336 KW. Somehow I doubt you'll get your phone system drawing anywhere near that 6 KW of power. Now, once you've determined that, you'll have to decide how to best power the equipment. You may want to follow standard telecom practice and have one or more 48V battery banks, with sufficient capacity to carry the system. Don't forget, you'll have to power everything that the phone system passes through. There shouldn't be much of a fire hazard with properly installed and maintained equipment. As for site power, fire protection etc., you'd better talk to someone qualified and not rely on what people here say. Doesn't the university have a facilities department, whose job it is to worry about such things? | ||||||||||||||||
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Posted by J. Clarke on June 28, 2005, 12:16 pm
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amahmood5@uclan.ac.uk wrote: > Hi all,
> > Voice over IP (VoIP) is a technology being considered where I work (a > University). We have a very large network with Cat5 outlets for data > and voice, but the voice is patched back to a regular telephone system. > > It would be nice to be able to connect all Cat5 outlets into an > PoE-capable Ethernet switch, then simply configure each port to the > voice or data VLAN. However, there are some issues that I'd like your > opinions on. If a typical wiring closet has 192 outlets (and our > network has LOTS of closets), and these are all patched into a PoE > switch stack, then that equates to about 6KW of power requirements > (rough figures from various sites). Does this mean > - I need to route a major power supply to the wiring closet? > - I need a colossal UPS to provide a decent amount of runtime? (By the > way, regular phone systems are protected by UPSes. Anyone know how > long they are meant to run in the UK? I'm assuming there's some kind of > regulation) > - That much power is going to generate a lot of heat. Do I need air > conditioning, which itself must be protected by the UPS? Generally speaking air conditioning would be run off a backup generator, not a battery. If the air conditioning shuts down for a few seconds while the generator kicks in it's no big deal, if the computers shut down then they go down dirty and have to reboot, which takes time and may lose data, hence the need for a UPS with fast switching. If this equipment is mission-critical and must stay up during an extended outage then everything should run off the generator with the UPS being a stopgap to bridge the period between the outage and the generator coming online. > - That much power represents a fire risk(?) - do I need a fire
> suppression system? If there is line voltage going into the area there is fire risk--the _amount_ of power is irrelevant. In any case that's one for the people with licenses to deal with such matters to worry about. In the US nearly all public or commercial buildings have sprinkler systems. The only time one worries about a "fire suppression system" is if the sprinklers will do unacceptable damage and it's necessary to put in an alternative to the sprinklers. > Suddenly a humble wiring closet needs the kind of very expensive
> environment previously reserved for server rooms. > > Any opinions greatly appreciated. > > Kind regards, > > Anwar -- --John to email, dial "usenet" and validate (was jclarke at eye bee em dot net) | ||||||||||||||||
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Posted by on June 28, 2005, 1:44 pm
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amahmood5@uclan.ac.uk wrote: >Suddenly a humble wiring closet needs the kind of very expensive
>environment previously reserved for server rooms. Suddenly your infrastructure is being asked to do something it never did before (or being asked to do it in a way it wasn't before). Sure, it's conceptually simple, but why should implementing a brand new phone system be cheap or easy? | ||||||||||||||||
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Posted by stephen on June 28, 2005, 11:35 pm
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> Hi all,
> > Voice over IP (VoIP) is a technology being considered where I work (a > University). We have a very large network with Cat5 outlets for data > and voice, but the voice is patched back to a regular telephone system. > > It would be nice to be able to connect all Cat5 outlets into an > PoE-capable Ethernet switch, then simply configure each port to the > voice or data VLAN. note - this means you get a phone OR a PC on each connection - so you are probably doubling the number of ethernet connected outlets. you can do that and make a manufacturer very happy, or you can use some of the phone / PC daisy chaining arrangements and roughly halve the number of ports. However, there are some issues that I'd like your > opinions on. If a typical wiring closet has 192 outlets (and our
> network has LOTS of closets), and these are all patched into a PoE > switch stack, then that equates to about 6KW of power requirements > (rough figures from various sites). 192 * 15.4w = 3 kW or so. Add in the power draw for the switch internals as well. maybe 6 kW if you have dual supplies - but the max draw is only 3 kW Does this mean > - I need to route a major power supply to the wiring closet?
if you provision to that then yes. but only 1/2 your ports will feed phones? - only build to what you need with some headroom. just remember most IP phones draw much less than the 13+ W available at the end of a Cat5 cable - around 2W for a nortel IP phone last time i asked. > - I need a colossal UPS to provide a decent amount of runtime? (By the
> way, regular phone systems are protected by UPSes. Anyone know how > long they are meant to run in the UK? I'm assuming there's some kind of > regulation) depends on your power arrangements - "real" high uptime sites have a jenny to take the load and the UPS is just there for paranoia and switchover time. i work for a Telco and our high paranoia / "nonstop" availability CPE with battery backup is set up for 4 hours. probably more a safety / legal issue than a technical one. > - That much power is going to generate a lot of heat. Do I need air
> conditioning, which itself must be protected by the UPS? No (or not as much as you are expecting) - you have to remember with PoE that the PoE power dissipation takes place in the cabling (the difference between the 15.4W worst case supply and the 13.whatever worst case device), and in the PoE device - which will be in offices rather than the wiring closet. the closet power will go up some as those new switches will generate more heat due to the PoE add ons - manufacturer data sheet should give the heat numbers (or you insist your supplier works it all out and underwrites it). > - That much power represents a fire risk(?) - do I need a fire
> suppression system? this is where you need to talk to the Uni fire officer..... >
> Suddenly a humble wiring closet needs the kind of very expensive > environment previously reserved for server rooms. just remember this is now part of a distributed PBX - and the one you are replacing probably eats a fair amount of power and money. And distributed systems usually cost more to build and run just because they are distributed..... >
--
> Any opinions greatly appreciated. > > Kind regards, > > Anwar Regards Stephen Hope - return address needs fewer xxs | ||||||||||||||||
>
> Voice over IP (VoIP) is a technology being considered where I work (a
> University). We have a very large network with Cat5 outlets for data
> and voice, but the voice is patched back to a regular telephone system.
>
> It would be nice to be able to connect all Cat5 outlets into an
> PoE-capable Ethernet switch, then simply configure each port to the
> voice or data VLAN. However, there are some issues that I'd like your
> opinions on. If a typical wiring closet has 192 outlets (and our
> network has LOTS of closets), and these are all patched into a PoE
> switch stack, then that equates to about 6KW of power requirements
> (rough figures from various sites). Does this mean
> - I need to route a major power supply to the wiring closet?
> - I need a colossal UPS to provide a decent amount of runtime? (By the
> way, regular phone systems are protected by UPSes. Anyone know how
> long they are meant to run in the UK? I'm assuming there's some kind of
> regulation)
> - That much power is going to generate a lot of heat. Do I need air
> conditioning, which itself must be protected by the UPS?
> - That much power represents a fire risk(?) - do I need a fire
> suppression system?
>
> Suddenly a humble wiring closet needs the kind of very expensive
> environment previously reserved for server rooms.
>
> Any opinions greatly appreciated.