The Lifecycle of Infrastructure
Staying on the right path of PoE.
- By Steve Surfaro
- Jun 01, 2011
What is the first thing you see in an organization’s income statement? Real estate and facilities rank among the most significant assets. However, these facilities would not be considered assets if organizations were not continually investing in and improving physical infrastructure as part of a capital project or periodic expansion.
These physical infrastructure assets—data centers, wiring plants and cabling facilities—exist to support the users and their edge devices. What better way to leverage this continually improving asset than to receive regulated, protected and supervised power to your network cameras, voice communications devices and wireless LAN access points?
Trace an Ethernet cable run to a wireless LAN AP at a large healthcare facility and you will not find an external power supply. Wireless patient monitoring and telemetry functions are achieved by devices powered via the Ethernet cabling that conforms to the IEEE 802.3af and 802.3at standards. The network-based surveillance cameras supporting many industries are no different and are a native part of this infrastructure maintained by the IT and physical infrastructure team, deployed by the systems integrator and improved through capital projects organized by owner/operators, architects/engineers, contractors and infrastructure lifecycle management professionals.
Video Surveillance
In addition to standards-based image quality, PoE is a primary driver for use and deployment of such network video devices as cameras and encoders in the physical security industry. Yes, even video encoders. In fact, video encoders get their power right from the Ethernet cable via any 802.3af- or 802.3at-compliant power sourcing equipment (PSE). Video encoders not only accommodate legacy analog solutions but are powered by the same network on which they stream their multimedia content.
For network video cameras, it is common to use Cat-5e cable supplying up to 12.95W of power via an 802.3af-compliant PoE PSE, which powers the outdoor fixed vandal-resistant dome cameras, with their integral heater and dehumidification device. A PoE+ or 802.3at PSE delivers up to 25.5W of power per the standard, and much more in many cases, which supplies the greater demands of the outdoor PTZ network cameras through the same cable.
Physical Access Control Systems
PoE+ IP-based PACS edge devices eliminate the door junction box and its associated power connection, enabling the cable contractor to leverage connectivity already present in the cable pathways. In fact, the previously common battery backup module also is eliminated when backup power is provided at the PSE. For example, the PoE+ 25.5 watts of power is enough for two doors and associated readers, locks, local annunciators and exit devices. The cost savings for these deployments far outweigh the additional care required to verify wiring plant and PSE compatibility and the selection of 12 volts DC locking devices.
The Basics
The PoE components in a system include the powered device (PD), which can be the network cameras, VoIP phones and wireless APs. The PSE delivers the power on the request of a compatible PD. PSEs may take the form of edge network switches, midspans and single-channel power injectors. The user is cautioned to choose industrial switches as PSE devices; consumer switches can often include non-isolated power, shared power supply across multiple ports and no backup power supply. If the user is in doubt or hesitant about upgrading the edge switches, a multi-port midspan can be an economical method of delivering highpower PoE while still permitting the use of legacy network switch devices.
How High Will We Go?
In a recent press release, Microsemi, a manufacturer of PoE solutions, announced availability of IEEE 802.3at-compliant 60W multiport PoE midspans, which deliver 60W via four-pair Ethernet cable powering and gigabit switching support.
Phihong USA offers 95W of power per port, more than any other midspan or PoE-enabled switch, primarily for applications such as computer workstations, LCD display panels and wireless access point (WAP) arrays.
Keep in mind that PoE+ or PoE Plus is the latest ratified standard by IEEE, or 802.3at. The HiPoE and High Power PoE designations are generally manufacturer trademarks.
Deployments at this extreme power level must always be accompanied by an analysis of cable, cable installation, supporting cable accessories, local compliance and dedicated data cables, negating any temperature concern and guaranteeing the safe and consistent operation.
How Long Can You Go?
The TIA/EIA 568-5-A standard for Cat- 5e cable states the maximum length for a cable segment is 100 meters (328 feet), and PoE and PoE+ devices must deliver their power within this distance. However, there are many devices and cable solutions that effectively extend the range of PoE. Some of these cabling solutions can stretch a PoE connection to 3,850 feet, and other products can connect network cameras in line with Ethernet cable to restore the network data and intelligently forward power to PoE devices for up to 1,000 meters (multiple devices). How can we manage this power and connectivity? Infrastructure management systems can integrate with your PSE to provide intelligent patching and provision services using the network to aggregate power usage reporting, which is necessary for scaling systems. Converging applications will require a more sophisticated network system and an open standards-based, centralized platform. What better way to realize this advantage than through standards-based power?
This article originally appeared in the June 2011 issue of Network-Centric Security.
About the Author
Steve Surfaro is an industry liaison at Axis Communications.