Power over Ethernet: Powering Unified Communications and More

Advancements in Power over Ethernet (PoE) promise more power and support for more devices. Learn how these upcoming enhancements will impact IP telephony in the enterprise.

IP telephony and PoE pack a powerful punch in the enterprise. With IP telephony, enterprises gain ease of management and a productivity boost. PoE introduces long-sought flexibility by freeing IT staff to install devices conveniently closer to the user population.

“We’re seeing an ever increasing number of customers choose PoE because it opens opportunities for IP phone deployment without being limited to the power source location,” says Franchesca Walker, marketing director of enterprise solutions at Foundry Networks.

Instead of connecting the phone to an electrical outlet, PoE powers the phone over the Ethernet cable. PoE transmits power along with data using two pairs on a Cat3/Cat 5 cable with a maximum current of 400 mA for a maximum load power of 15.4 W IP telephony handsets need only 12W.

In today’s enterprise environments, PoE represents about 20 percent of all switched Ethernet ports. Analysts expect the demand for PoE to increase, with forecasted sales for PoE ports to reach 116 million ports by 2010, according to the Dell’Oro Group Ethernet Forecast, published in January 2007 (see figure).

The PoE strategy at ShoreTel®, a leader in Pure IP Unified Communications solutions, aligns with the industry forecast that more enterprises will be migrating to PoE. ShoreTel IP telephones come with support for the current IEEE 802.3af PoE standard, and they can only be powered by PoE. “The majority of customers want to power their phones with PoE,” say Dieter Rencken, senior product manager of IP Phones at ShoreTel. “Customers that do not have PoE-enabled Ethernet switches must install mid-span, single- or multi-port PoE injectors.”

As more enterprises adopt VoIP infrastructures, they are finding that PoE gives them a number of valuable advantages. With the elimination of separate phone cables, IT can deploy handsets in more places within the organization. PoE also supports a growing number of devices; wireless LAN access points, security cameras and environmental sensors, among others, can all be powered with PoE. The surveillance cameras can be in a hallway or anywhere they are needed, rather than where the power outlet is located. Again, PoE brings flexibility and ease into environments that require these types of devices.

On the maintenance and planning front, PoE can save IT professionals time and energy. “The network manager choosing the right PoE switch that supports full Class 3 devices on every port maximizes the capital return from the PoE investment and simplifies supporting the user community,” explains Ms. Walker. “Because power is handled by the switch, you can eliminate power starvation points.”

According to Ms. Walker, a major challenge enterprises are facing with PoE is power redundancy in support of business continuity. “When there is a power outage, the POE devices must be supported by a second power source. A redundant and removable power supply system will enable a switch to get power from more than one power supply. This type of solution maximizes the amount of power available to the POE devices. Foundry switches offer this high availability and can automatically move to a secondary source.”

Another PoE concern is the form factor of current power supplies. At this point, the industry will need to encourage power supply makers to continue to improve their products by reducing the form factor and energy requirements. “Today power supplies aren’t compact enough for compact switches to accommodate internal power redundancy,” says Ms. Walker. “It’s a technology challenge for power supply manufacturers. The industry should begin considering how to be greener and deliver power supplies with a smaller footprint.”

New Standard Under Consideration
A new PoE standard, PoE Plus (802.3at), is gathering momentum within the market. PoE Plus is much more robust and supports more devices. Power wattage increases from 30W to 40W under PoE Plus. In addition to supporting IP telephony phones, Wi-Fi access points, biometric access controls and video cameras, PoE Plus can support video IP phones, workgroup switches, pan-tilt cameras and laptops. Another piece of good news is that PoE Plus is backward-compatible with the current standard (802.3af).

“We’re seeing increased interest around PoE Plus, especially for its support of workgroup switches,” says Ms. Walker. “Enterprises can put workgroup switches anyplace with PoE Plus. They are not handcuffed to the wiring closet. They can move workgroup switching into a PC cluster in the office area. Laptops and workgroups will be powered from a central area, which means switches, laptops and IP telephony phones can be deployed where they are most needed.”

She points out that PoE Plus will find more usage in specialized environments and for high-end endpoint devices. “In environments that only use PoE for IP telephony, PoE Plus is overkill,” she says. According to Rencken, most ShoreTel customers will not require PoE Plus.

Look for Future Improvements
Other PoE enhancements not associated with the new PoE Plus standard are already underway. For example, expect to see PoE-enabled switches that can auto-detect power. This enhancement dovetails nicely with current green initiatives and requirements to reduce energy costs.

“Protocols are available that will take power requirements from the endpoint and send it to the Foundry switch equipment,” says Ms. Walker. “The switch will acknowledge the endpoint’s power requirement and decrease the amount of power sent to that endpoint. If the devices only need 7 watts instead of a full 12.5 W, the switch will provide the exact power based on what the device needs.”

ShoreTel shares this spirit of providing a greener option to customers, says Rencken. “We are always looking to design less power-hungry phones.”

With so much activity around PoE, enterprises will need to keep an eye on current developments. “PoE promises a lot of convenience for the enterprise,” says Ms. Walker.