While several new networking technologies have been introduced in the past few years, Voice over IP (VoIP), which had a breakout year in 2004, is emerging as a critical IT concern for businesses. Moving to IP telephony is a key decision in the evolution of an enterprise network, and as such, administrators demand – and are experiencing – the high availability and voice quality as found with traditional circuit switched telephony systems. In addition, administrators are also gaining a host of value-added features with their VoIP deployments such as increased bandwidth, simplified infrastructure and lower phone operating costs.
Power over Ethernet (PoE), IEEE standard 802.3af, greatly contributes to the simplicity and availability of VoIP deployments. This standard allows a convenient and cost-effective powering of the phones (no local desk DC power needed) as well as simple, centralized power protection of the whole installation directly from the switch/wiring closet.
VoIP brings significant advantages over traditional enterprise telephony networks. These advantages, which include reduced carrier circuit charges, enhanced applications from desktop video conferencing to voice-enabled Web sites, integrated management systems and strategies, and increased flexibility for a reduction in overall complexity and elimination of circuit redundancy, all contribute to the steady increase in the adoption of the technology.
For these reasons, VoIP is experiencing fast growth. According to Venture Development Corporation’s report “Power Over Ethernet: A Global Market Demand Analysis,” the worldwide market for PoE midspan solutions is expected to steadily rise, doubling the number of PoE-enabled ports shipped each year between 2003 to 2007.
Powering the Converged Network
PoE, which integrates data, voice and power over a standard LAN infrastructure, is the means to supply reliable, uninterrupted power to IP telephones, wireless LAN access points, network cameras and other collaborative Ethernet devices, using existing Cat-5/5e or 6 cable infrastructure.
Power over Ethernet integration diagram
PoE technology saves time and reduces costs associated with the installation of separate power cabling, AC outlets and wall warts (AC adapters) as well as eliminates the need for a dedicated UPS for individual devices. One centralized UPS protects the switches and the connected devices.
The power delivered over the LAN infrastructure is automatically activated when a compatible terminal is identified and blocked from legacy devices that are not compatible, thus protecting them and the infrastructure. This feature allows users to freely and safely mix legacy and PoE-compatible devices on their network.
There are two main implementations of PoE power source equipment – the midspan and end-span. The midspan or power hub is a patch-panel like device, residing between the Ethernet switch or shared media device and the terminals. Power is added to the spare wires on a Cat-5/5e or 6 cable while the data is passed without interruption. With an end-span, PoE is integrated into the switch and supplied directly from the data ports.