tailieunhanh - New Life for VoIP

Tham khảo tài liệu 'new life for voip', công nghệ thông tin, phần cứng phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Power Over Ethernet New Life for VoIP white paper Final approval of the Power over Ethernet PoE standard in June 2003 removed a significant barrier to widespread adoption of IP telephony. The standard IEEE specifies how to supply power to compliant devices over Ethernet LAN cabling. Armed with uninterruptible power supplies UPS IT staff can now deploy Voice over IP VoIP telephones without worrying about them not functioning during a power outage. This of course is a well-tested idea. Public telephone companies have been using a similar strategy for over a century to ensure reliable service to their customers. The benefits of this enabling technology are not limited to IP telephony however. Many applications that deploy equipment with low power requirements in areas that aren t already wired for power will benefit from reduced cabling costs. A single standard Ethernet cable will now be able to provide both power and communication services to wireless network access points IP cameras security badge readers and many other devices. A list of the advantages PoE confers includes Reduced cabling costs. One set of wires provides both power and data. Reliability. A UPS at the power distribution source can guarantee power to all connected devices. A worldwide power standard the first. This means that PoE devices will plug in anywhere. SNMP network management. This system can be used to monitor and control connected devices including resetting them and shutting them down remotely. Simplification of wireless LAN installation. Access points can be moved and wired in easily. Technology Overview The standard defines two new hardware components. The first power sourcing equipment PSE is responsible for supplying up to watts of power at 48 volts to the second called the powered device or PD. The two types of PSEs DTE and midspan PSEs also called midspan controllers are discussed below. DTE PSEs DTE PSEs are PoE-compliant Ethernet switches and are sometimes .