HomePlug Powerline Alliance
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HomePlug is an industry trade group for power line communication. This organization of about 50 companies defines power line communication specifications. HomePlug 1.0 and AV are the two versions of the specification for home networking technology that connects devices to each other through the power lines in a home. HomePlug certified products connect PCs and other devices that use Ethernet, USB, and 802.11. Many devices have HomePlug built in and to connect them to a network all one has to do is plug the device into the wall in a home with other HomePlug devices. Since surge protectors and similar devices may interfere with the high-frequency signals used by HomePlug, the directions included with HomePlug devices recommend plugging them directly into the wall outlets without using extension cords or outlet strips.
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[edit] Operation
Since the signals may travel a short distance outside the user's residence or business, like many other network standards, HomePlug includes the ability to set an encryption password. As with many other networking products, most HomePlug devices are Secure by default. The HomePlug standards require that all devices are set to a default out-of-box password - although a common one. Users should change this password.
To simplify the process of configuring passwords on a HomePlug network, each device has a built-in master password, chosen at random by the manufacturer and hard-wired into the device, which is used only for setting the encryption passwords. A printed label on the device lists its master password.
The data at either end of the HomePlug link is not encrypted (unless an encrypted higher-layer protocol such as TLS or IPSEC being used), only the link between HomePlug devices is encrypted.
Since HomePlug devices typically function as transparent Ethernet bridges, computers running any operating system can use them for network access. However, some manufacturers only supply the password-setup software in a Microsoft Windows version; in other words, enabling encryption requires a computer running Windows [1]. Once the encryption password has been configured, Windows will no longer be needed, so in the case of a network where all computers run other systems a borrowed laptop could be used for initial setup purposes.
In residences and small businesses with Split phase wiring (common in North America), roughly half the 120-volt outlets in the building will be on each hot phase, and HomePlug signals may or may not be able to get from one side to the other. If one is unlucky, this may prevent some rooms from being connected via HomePlug.
Among other things, HomePlug brings back the ability to use Ethernet in bus topology, implied by its standard description (carrier sense multiple access and collision detection) and very desirable in some circumstances. This is achieved by use of advanced OFDM modulation that allows co-existence of several distinct data carriers in the same wire pair.
[edit] Current and proposed functionality
The HomePlug powerline alliance has defined the following standards:
- HomePlug 1.0 — Released June 2001 — Specification for connecting devices via power lines in the home. Now AV offers better performances.
- HomePlug AV — Released December 2005 — Designed for transmitting HDTV and VoIP around the home.
- HomePlug Access BPL (BPL) — under development — A working group to develop a specification for to-the-home connection.
- HomePlug Command & Control (HPCC) — under development — It's a low-speed, very low-cost technology intended to complement the alliance's higher-speed powerline communications technologies. The specification will enable advanced, whole-house control of lighting, appliances, climate control, security and other devices.
[edit] 1.0
The original HomePlug 1.0 standards allow for speeds up to 14 Mbit/s half-duplex.
Many old 85 Mbit/s devices are erroneously referred to be HomePlug. They are instead based on Intellon's proprietary 85 Mbit/s Turbo mode. The error is induced by the fact that INT5500 Chip Set is compatible with both HomePlug 1.0 specifications and Intellon Turbo technology and the two technology are called HomePlug 1.0 with Turbo on the whole.
[edit] AV
The current HomePlug AV standard allows for speeds up to 200 Mbit/s half-duplex (which may be suitable for applications such as HDTV and VoIP). HomePlug 1.0 device cannot interwork with HomePlug AV devices without the use of a suitable bridge, although both can co-exist on the same cable.
[edit] BPL
The alliance is developing a standard called HomePlug BPL for last-mile access networks.
[edit] Command & Control
[edit] Interoperability
The alliance certifies products for HomePlug compliance. Devices marked with the certification mark will interoperate with each other. However, they will not work with the newly-formed CEPCA (Sony, Mitsubishi and Panasonic) which has developed powerline technologies which can offer speeds up to 170 Mbit/s.
HomePlug is participating in the developing IEEE P1901 standard together with many others and particularly its competitors CEPCA and UPA. This leave good chances to have an unified power line communication standard in the future.
[edit] HomePlug AV Devices
- devolo - dLAN 200 AVdesk, dLAN 200 AV, dLAN NAS, dLAN NAT
- D-Link - DHP-301
- Linksys - PLE200
- Netgear - HDX101
- ZyXEL - PLA-400
- Other: Arkados, Inc., GigaFast, Intellon Corporation, MainNet Communications, SPiDCOM, Yitran
