VoIP migration involves a lot of considerations, but one thing many
networking and voice professionals tend to overlook is the
additional power it will take to keep a VoIP deployment running
smoothly.
According to some experts, powering VoIP, especially when using
Power over Ethernet (PoE), can add massive overhead. For many, that
extra power comes as quite a surprise.
"PoE for VoIP is just the first step; you're going to be
powering more devices," noted Gary Audin, president of Delphi Inc.,
who has written extensively on power related to VoIP.
As more and more companies turn to LAN switches to power their
VoIP deployments with PoE, Audin said, a good number fail to ensure
that the wiring closet and data centers are ready to handle
increased power consumption. In some cases, new wall sockets are
required in order to power the switches that run PoE. In extreme
cases, Audin said, an enterprise may have to rely on its utility
company to run more power to the building itself.
Audin estimates that on a simple per-phone basis, running VoIP
requires roughly 30% to 40% more power than old TDM phones. Running
more equipment in the closet is also going to increase the amount
of heat generated, requiring additional cooling, which in turn
sucks up more power.
Audin suggests that companies considering PoE first determine
whether they have enough power in the closet for power
supplies.
Daniel Feldman, product line manager for Microsemi -- an analog,
mixed signal and semiconductor manufacturer that acquired PoE
vendor PowerDsine early this year -- said VoIP power consumption
can increase based on the number of features needed for phones,
while basic IP phones can still consume a small amount of power.
Feldman said that companies, before moving forward, should plan for
the number of phones, number of concurrent calls, and the amount of
power dedicated to those phones.
"It's important to size the power supply," he said. "Do the
analysis."
That analysis should consider the power consumption of IP
phones, the IP PBX, switches, mid-spans and cooling systems,
Feldman said. In many cases, he added, switches require more power
than mid-spans.
As a rule of thumb, Feldman said, when considering power, "you
get what you pay for."
Increased productivity outweighs increased power
costs
Fred Weiller, Cisco's director of switching product marketing
for network systems solutions, said that although PoE may appear
more expensive on the surface -- with increased equipment and power
costs -- overall, a company can enjoy savings.
"Using PoE is not really going to drive the company to use more
power," Weiller said. "WLAN [access points] or IP phones; you're
going to have to power them somehow, you're just going to have to
power them a different way. You're still consuming the same amount
of power."
Weiller argued that because PoE is centrally managed and
provisioned, it offers better redundancy. PoE also leads to boosted
productivity and eases moves, adds and changes, he said. Those
factors reduce the overall cost of a PoE deployment.
"You achieve cost benefits in some areas while paying more in
others," he said. "Let's say PoE is a little bit more expensive. A
company can more than recoup the cost from operational
benefits."
Looking at just the increased power costs is shortsighted,
Weiller said. Better integration of applications, boosted
productivity and freed up IT resources are gains that can soften
the blow of a higher energy bill.
"You always need to step back and look at the total cost of
ownership," he said.
Delphi's Gary Audin said, however, that TCO will include
significant energy costs, especially since the price of power
fluctuates continually, usually increasing.
If PoE is important, Audin said, companies will need a dual,
fault-tolerant power supply. Both have to be running, but running
both absorbs energy and creates heat, generating more energy
costs.
"This will not only increase the power supply costs but will
double the utility power consumption," he said.
Battery-powered backup
Then comes the issue of battery backup. Batteries take up a lot
of space and are quite weighty. Companies have to evaluate whether
they have room for battery backup in the closet, or closets in a
distributed environment. From there, companies need a centralized
system to monitor and keep tabs on deployed batteries to ensure
that they have enough power and are running properly.
In addition, some cities and towns have building codes that
require ventilation if backup batteries are in place, whether or
not the batteries are sealed.
Essentially, Audin said, keep the checkbook handy.
"None of this is typically in the IT budget," he said.
Audin related a story of an 8-by-12-foot wiring closet that was
empty except for four PoE switches and four power supplies. Those
four alone created enough heat to require additional air
conditioning.
Even with VoIP outsourcing, power costs can be an unexpected
hit, Audin cautioned. Some providers of hosted services now list a
separate line item for power costs that the customer pays in
addition to the standard rate.
Weiller agreed that the market needs education. He said PoE
gives about 15 watts per port, which on the surface doesn't sound
like much. But when running, say, 400 ports, it adds up.
Standardizing PoE
Also, a proposed new PoE standard, 802.3at, could boost the
amount of power per cable to 45 to 50 watts, compared with the
roughly 15 watts of the current 802.3af standard, Audin said.
Basically, that means that even if an organization puts in enough
power today, it will still have to adapt for the future. That new
standard, referred to as PoE Plus, is said to deliver greater
electrical power to devices besides IP phones. Couple that with the
expectation that the new standard will cover 1 gig and possibly 10
gig transmission speeds, and companies have more factors to
consider.
Audin said that as PoE output increases, so does the power to
the PoE power supply, which could double or triple the power needed
from the LAN switch. Companies will also have to upgrade UPS
systems for PoE Plus requirements, along with adding extra air
conditioning to support the PoE Plus power supplies.
Basically, Audin said, power costs will climb and future-proofing
will be a never-ending cycle.
Some users, who are in the process of a VoIP migration, said
they are taking power into consideration.
"Do we want to use PoE switches?" is one question Bruce
Kilbourn, manager of telecommunications for John C. Lincoln Health
Network in Phoenix, Ariz., said he's weighing. "Power is a
consideration."
Kilbourn said, however, that all of the health network's wiring
closets are already air conditioned, so he won't have to worry
about extra heat created if PoE is ultimately rolled out. He said
he is currently weighing whether using PoE or AC receptacles will
be a better deal in the long run.
David Bernhagen, network operations manager for Maitland,
Fla.-based Concord Management Limited, said he agrees that many
companies can overlook the increased power costs associated with a
VoIP deployment. He said he's been evaluating power issues while
looking to deploy VoIP internally to reduce costs.
"I think a lot of people don't realize the amount of power
needed for PoE," he said. "We've always been aware of power
consumption issues. We're cognizant."
And cognizant is just what companies should be, advised Irwin
Lazar, principal analyst and programmer with Nemertes Research.
"This is a huge issue," Lazar said. "Enterprises need to address
environmental controls such as closet air conditioning and/or
ventilation. They need to address fire code requirements, and they
need to have a strategy for power backup for all devices in the
VoIP chain, including routers and switches. Power planning needs to
be part of the initial architecture and design to avoid
surprises."
Cisco's Weiller agreed.
"Do you have the right power capabilities in your wiring closet
to drive PoE ports and the rest of the switching?" Weiller asked,
adding that every company should consider that question before
spending money on PoE equipment. "That should be part of the
project, not just an afterthought. It has to be part of the
planning and discovery."