* Empowering convergence using Power-over-Ethernet
As companies move forward with their VoIP rollouts (96% of 68 IT execs polled in a recent Nemertes benchmark say they’ve either deployed VoIP or plan to do so within the next 12 months), one issue they often neglect is ensuring appropriate power. Power-over-Ethernet (based on the 802.3af standard) ensures that the data and power delivery are also “converged.” This has significant implications for reliability.
As companies move forward with their VoIP rollouts (96% of 68 IT execs polled in a recent Nemertes benchmark say they’ve either deployed VoIP or plan to do so within the next 12 months), one issue they often neglect is ensuring appropriate power. Power-over-Ethernet (based on the 802.3af standard) ensures that the data and power delivery are also “converged.” This has significant implications for reliability.
Make sure your switches and routers support the 802.3af to deliver line power to phones. Why? Utility grid power delivers only about 99.9% availability, which equates to 48 hours of downtime per year. Line-powered phones can be backed by uninterruptible power supply to deliver five- to six-nines of availability.
In making a decision on whether to support PoE you have to consider the cost of converting your wiring closets vs. the potential for much reduced availability of phone services. Delivering UPS quality power to each and every power socket in your buildings is unlikely to be a viable solution. Effectively, PoE converges power and data on the same cable, while adding a new power quality “tier” to your facilities. You end up with two parallel power infrastructures: grid power for bronze-level power needs (with the expected outages and fluctuations) and platinum-level power for phones and other critical devices.
Local phone companies typically guarantee 8-hours of runtime in the event of a power outage. Effectively, the phone companies maintain huge banks of rechargeable batteries so they can deliver DC power over POTS during an outage. Since there aren’t yet regulatory requirements governing VoIP phone runtime, a good rule of thumb is to plan to guarantee 1- to 2-hour of phone runtime – that gives users ample time to phone emergency services and organize an evacuation, if required.
Implementing 802.3af as recommended can dramatically increase the cooling and space requirements of wiring closets, where switches and UPSes are typically located. Make sure yours are amply configured. Each wiring closet now acts as a converged data/power switch. Incoming high-capacity data and high-amperage power are both split and distributed to individual network nodes over the structured cabling.
With PoE you can begin to treat power as an IT-related service that is delivered according to the required service-level agreements (SLA) of your business. Extending reliable power to the end-point (phone) ensures that your “uptime” calculations are meaningful. Since an IP phone with data but no power is useless, it is likely that in many businesses without PoE, estimated reliability figures for VoIP are inaccurate by two orders of magnitude – data may be engineered at five-nines (99.999), while power is delivered by the utility with no more than three-nines (99.9). At the end of the day, you will be exposed to the reliability level of the weakest link: power.
PoE is not limited to phones. Once you have the capability to deliver PoE you will start finding more and more possible uses for it: wireless access points, security cameras, biometric and other physical access controls, environmental controls, etc. Despite almost a hundred years of development, utility power is still mostly unsuitable for electronic devices – hence the number of “wall-warts” (those ugly black transformer blocks that are powering every DC device in your office). It is time to focus on the devices that are the majority in an office environment: sensitive electronics with a need for high-quality uninterruptible low-amperage DC power.
