Power over Ethernethas been around
for some time, but the standard is evolving and this could have
implications for designing corporate networks, writes Carrie
Higbie, president of theBlade Systems
Alliance.
Power over Ethernet describes a system to transmit electrical
power, along with data, to remote devices over cables in an
Ethernet network. This technology is used in powering IP telephones
and wireless Lan access points.
Standards body the
IEEE is working on
Power over
Ethernet Plus (PoE Plus), which will effectively double the
amount of power provided over a data cable. This will enable a wide
range of capabilities, such as PTZ (pan tilt and zoom) for video
cameras, extended range wireless access points, and extended video
capabilities within VoIP phones.
PoE Plus is geared towards providing greater power (>30
Watts) for hardware that requires more than 12.95W at the end
device. Heat dissipation is directly affected by conductor size and
resistance and it is likely that newer 10gbps copper cabling
systems, such as category 7/class F and category 6A/class EA are
likely to prove to be better choices for higher power due to larger
conductor size.
At present, category 7/class F is also the only published
standard to support 10GBase-T over 100 metres. Although the new
standards generally try to address installed cabling plants, the
safest bet for new installations is to
use the highest performing cabling possible as there may be
less restrictions in the future.
Facilities may need to install higher amperage breakers and, in
some instances, move to higher gauge electrical wire to support the
increased power demands in the telecoms areas. Whatever type of
power sourcing unit you install, it is important that it be able to
throttle down power when it is not needed.
Other benefits that may be realised over time revolve around the
Energy
Efficient Ethernet work being done by the IEEE. One
disadvantage to powered patch panels is that the systems are
installed into an infrastructure that is designed to last 10 to 15
years. This may limit those installations from taking advantage of
the new energy efficient technologies being developed.
Ethernet ports draw power when idle. With green initiatives on
the rise, work on Energy Efficient Ethernet aims to find ways to
shut down the ports during idle states, throttle back bandwidth,
and may even translate into management schemes that would allow
VoIP phones, for instance, to power down to low state power after
hours.
In a switched environment, power can be dedicated on the fly,
rather than requiring a patch cord change or retermination. The
newer switches also allow for static power allocation as well as
dynamic. Network managers can dictate a maximum amount of power
that will be supplied to a port, although the device may not draw
that amount of power at all times, the remaining power can be
returned to the power budget when the device is in a quiescent
state.
The ability to upgrade to more efficient power as technologies
evolve without having to reterminate connections will be labour
savings. Likewise, a single point of management and single
connections into redundant power as opposed to two for mid-span may
mean the difference between multiple uninterruptible power supply
units as opposed to single ones. Mid-span devices outside of patch
panels also take up additional rack space which is not available or
a challenge in some environments.