Converged networking is a concept that has been around since the late 1990s. It originally implied that separate voice and data bit streams could be merged or converged into a single network. The idea was revolutionary, especially for the telephone operating companies that had just undergone deregulation. The technologies supporting this concept meant that service providers were now able to deliver more services, at a lesser cost. This was good news for the consumer and the enterprise alike.
As technology evolved, the idea to converge even more services unto “the network” also evolved. It did not take long thereafter to see video streams added to the mix. Having the technology to converge voice, data, and video led to a number of innovations in the development of new network devices (“appliances,” as they are now called), along with an array of new network applications.
Today, the enterprise network has evolved in versatility and complexity, to the point where the once-called peripherals or appliances hanging off its edges, have become important network assets.
Powering Devices Through the Existing Cabling
During this evolution, a compelling business case to power devices through the existing structured network cabling infrastructure has emerged. Early devices such as IP phones consumed very little power and the idea of using existing Cat5e UTP network cabling to power the IP business phone seemed like a novel idea.
Fast-forward 15 years later to today, and what seemed like an interesting concept at the time has now become a genuine method for powering an array of edge devices.
Power over Ethernet: The Modern Method
The method for applying power over network cabling is called Power over Ethernet (PoE). PoE has been around for the past 15 years and is a reliable and robust way to deliver DC power over Cat5e and Cat6 network cabling. As edge devices evolved, so did the demand for increased power. The first PoE-powered phones were deployed in 2000 and consumed as little as 7 watts (7W). By 2003, Wireless Access Points (WAP’s) and fixed CCTV cameras were added to the mix of edge devices. That year, the IEEE802.3af standard was ratified and allowed for the support of 12.95W devices. As the demand to add more devices and device types, so did the demand for more power. In 2009, IEEE802.3at, also known as PoE+ or PoE Plus, was published to allow for 25.5W devices. By 2011, equipment manufacturers were pushing the envelope to the point where PoE switches were delivering up to 60W over the network and this up to 100 meters away.
|Typical power consumption
|Wireless Access Points (WAP’s)
|> 30 watts
|Digital signage and lighting
|Brushless drives, motor control
|> 30 watts
|Building Security Systems
|Pan, Tilt, Zoom (PTZ) cameras
|Thin clients, virtual desktop terminals
|Variable air volume controllers, access controllers
|Banking / Financial
|Point of sale devices
|Nurse call systems
Table 1: Existing, new, and emerging PoE applications
A New Standard
In order to keep up with equipment manufacturers, corporate demand, and the ever-growing number of network edge devices that are being developed, the IEEE 802.3 committee is reviewing its current standard. The IEEE802.3bt Task Force was established in 2013 and is scheduled to be ratified sometime in 2015. The new standard will be specifying methods, protocols, and guidelines to allow the transmission of DC power over standard network cables with the goal to support 60W PoE edge devices.
We now have a network that offers more options and versatility with the opportunity to replace the conventional and expensive electrical infrastructure supporting those devices. This is good news. However, one must take a closer look at the impacts and implication of energizing the network with up to 60W of power. Many good articles and white papers have been written on the subject and all point to one nasty note of caution. They all bring up and discuss the effects of dc current on cable temperature. Applying this much power on say, a Cat5e 100-cable bundle, can increase the cables’ temperature by up to 10 degrees Celsius. This has a direct effect on the lifespan of the cable, and its transmission characteristics (i.e. higher cable temperature = more loss = transmission degradation). One should note that a higher-gauge network cable, such as a Cat6 or Cat6A, is much better at dissipating heat than a Category 5e type cable.
One such article articulates the issue as follows:
The IEEE 802.3bt four-pair PoE standard is expected to assume a maximum temperature rise of 10 degrees Celsius when all four pairs are energized. For cabling with an operational temperature range of -20 degrees Celsius to +60 degrees Celsius, the ambient temperature should not exceed 50 degrees Celsius. Using a higher category cable with lower dc resistance and improved heat dissipation can help reduce the rise in temperature. Consequently, it is recommended that Category 6A cabling is used for four-pair PoE applications. Because increased thermal loading can also increase insertion loss, the maximum cable length should be de-rated for higher temperatures, per ANSI/TIA-568-C.2 Balanced Twisted-pair Telecommunications Cabling and Component Standard. 1
Planning for Network “Power” Requirements
The selection of different Category type network cable was, and still is, associated with transmission speeds – the higher category type cable is associated with higher transmission speeds. In light of the new upcoming PoE standard, one must now consider and plan for network “power” requirements.
Besides cable selection, careful consideration will also have to be given in the proper selection of connectors, patch panels, and other connection points. The new PoE is certainly a game-changer and brings many benefits. To capitalize on these benefits, make sure that you do your homework before investing into a brand new cabling infrastructure.
FCi is the leader in providing Ottawa Cabling Solutions. Contact us to learn more about powering edge devices and network power requirements.