Introduction
Traditionally, devices connected to the network need to be connected by at least two types of cables. They are an Ethernet cable for transmitting data and a power cable for power supply. The need for power cords has been a limiting factor in device deployment, either by placing the device near an existing power outlet or by installing a new power outlet near the device. Power over Ethernet (PoE) solves this dilemma and greatly increases the flexibility of deploying such devices.
PoE is a revolutionary technology that is rapidly being used on devices like VoIP phones, IP video surveillance and wireless access points. With the first release of the PoE (IEEE802.3af) standard in 2003, the market has grown substantially. According to InfoneTIcs, the number of global PoE ports increased from 25 million to 63 million from 2005 to 2010, and it is expected to exceed 80 million in 2012. PoE technology not only provides data transmission but also provides power output through the same Ethernet cable, which makes device deployment more convenient and greatly reduces the power line requirements. Before using PoE technology, network devices require separate cables to power and transmit data. Since the device must be close to a power outlet, it has been a limiting factor in device deployment.
As the silicon manufacturing process improves and the chip consumes less power and the chip consumes less power, the overall power consumption of the Ethernet device is continually decreasing. This greatly expands the range of devices that can support PoE.
What is PoE?
PoE technology can simultaneously transmit data and power on the same Ethernet cable. Among an Ethernet Category 5 cable, there are four pairs of unshielded twisted pair (UTP) cables. In a typical Fast Ethernet connection, only two pairs of cables are used for data transmission (all four pairs of cables in a Gigabit Ethernet connection are used for data transmission). PoE uses two of the four pairs of unshielded twisted pair cables to power devices connected to the same network cable. For Fast Ethernet, the two pairs of unshielded twisted pair used to power the power are usually two pairs of wires used to transmit data (see Figure 1).
Figure 1: Category 5 cable that supports PoE in a Fast Ethernet environment
A powered device (PSE), such as a PoE switch or a powered device between a non-PoE switch and a PoE device, powers a powered device (PD). A powered device (PD) includes a wireless local area network access point (AP), an IP camera, an IP phone, a PoE webcast, or an RFID device. 802.3af classifies the powered devices (PDs) based on power consumption to ensure that the power supply equipment (PSE) can effectively provide power output within the range required by the power supply (see Table 1).
As a power supply device, the PSE has the following three functions:
• Detect powered devices and determine how much power they need
• Provide sufficient power as needed
• Monitor and stop power as needed
Table 1: 802.3af device classification
Enhanced Power over Ethernet (PoE+)
The growing demand for PoE power from more devices has contributed to the development of the IEEE 802.3at (known as PoE+) standard. The higher power of PoE+ provides new possibilities for PoE powered devices. Today, PoE powered devices include rotary and zoom (PTZ) cameras, video phones, high-definition displays, and low-power embedded systems. The new standard is backward compatible with 802.3af, increasing the maximum available power for powered devices to 25.5 watts and allowing powered devices to negotiate their exact maximum power.
By eliminating the need for dedicated power cords and outlets, organizations can increase the flexibility of device deployment and provide power output for locations where previous direct current (AC) power could not be powered.
Enterprise-oriented PoE applications
The installation and use of PoE is growing dramatically; as more powered devices enter the market, PoE will become a must-have feature for many enterprise and mid-sized business users. Here are some common PoE applications for the enterprise:
Figure 2: Example of connecting devices via PoE in a commercial environment
Enterprise VoIP
Both analog and digital telephones of traditional private branch exchange (PBX) receive and power over connected telephone lines, avoiding separate AC power connections. Similarly, a VoIP phone designed to transmit compressed digitized voice data over a network can also receive operational power output when connected to a PoE switch.
While most VoIP phone manufacturers offer AC adapters to power the phone, they use PoE power instead of directly powering IP phones. When the PoE switch used to power the IP phone is connected to an uninterruptible power supply (UPS), the power supply of the IP phone does not interrupt the power supply even in the event of a power outage, and the reliability of the system is greatly improved. PoE also increases the flexibility of deployment, allowing IP phones to be deployed where there is a network connection, regardless of whether there is a power outlet nearby.
WLAN integration
In many environments, it is impractical to limit the placement of wireless access points to places where AC power is nearby. Using PoE switches can reduce the cost of power installations and provide enterprises with the flexibility to deploy wireless access points based on coverage rather than power constraints.
Simple deployment of IP-based security solutions
The separate wiring and dedicated features of traditional monitoring systems are not cost effective. IP-based surveillance solutions—using Ethernet networks to send video signals—provide enhanced performance, such as recorded data that can be stored directly on a standard PC or network storage device, with remote access to records over any network connection. It can also be integrated with additional applications like special point of sale (PoS) solutions.
PoE switches, along with IP surveillance systems, simplify the installation and reduce overall cost by leveraging the same Ethernet cable to carry video data and camera power.
benefit
Overall, companies benefit from the following aspects through PoE switches:
• Simple deployment: Today's network devices only need to have one RJ-45 network port on the hardware, eliminating the need to provide different power supplies for devices sold in different regions;
• Mobility and flexibility: No matter how far the AC outlet is, wireless access points and IP cameras can be deployed where needed;
• Reliability: When a PoE switch is connected to an uninterruptible power supply (UPS), power is guaranteed even in the event of a power outage;
• Cost efficiency: avoids the time it takes to install the power infrastructure and maintain the power system;
• Enhanced management: centralized power and data management allows remote monitoring and management of wireless access points, IP cameras or other powered devices;
to sum up
PoE switches provide improved reliability, cost reduction, and ease of deployment for powered devices. As the power consumption of Ethernet devices decreases, more and more devices will be able to be powered by PoE. NETGEAR's reliable, cost-effective and easy-to-use PoE switches will enable new, advanced, and powered devices to work seamlessly, saving companies time and money. NETGEAR PoE switches: In short, smarter.
NETGEAR Delivers Smarter PoE Solutions for Converged Networks
Regardless of the size of your business, NETGEAR always provides a reliable, cost-effective and easy-to-use PoE solution for your converged network applications.
NETGEAR PoE Smart Switches are designed to deliver high performance, network intelligence and reliability to enterprise networks without cost or additional complexity. PoE's support makes it easier to install devices like IP webcams, wireless access points and IP phones without the need for a power outlet nearby.
The NETGEAR PoE Smart Switch delivers up to 30W of PoE+-based power – enough to power a high-end PTZ camera.
With NETGEAR PoE Smart Switches, organizations can simplify ordering, design, and installation enablement. All smart switches feature high availability and "smart" management features, making it easier to configure, monitor, and troubleshoot switches while maximizing uptime. Hardware stacking allows you to add more switching capacity without the need for the switch to go offline.
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