Plug Into Power-Line Networking

I was wondering if you could tell me if the terms HomePlug and HomePNA mean the same thing? I’ve seen them used a number of times, but I’m not quite sure what they mean. Is it just another way of describing power-line networking?

Well, you’re half right. HomePlug networks are used in houses that are not wired with Ethernet cable and have difficulty running wireless connections due to interference of one kind or another (i.e., concrete walls, excessive steel or radio interference). HomePlug, which is another way of describing power-line networking, makes use of the existing electrical power lines in your home’s walls for data conductivity and is capable of speeds of around 10Mbps. You can find more detailed information about this technology on the HomePlug Web site.

Before I ordered my new DSL line I was told that I would still be able to use my fax machine. However, since DSL been installed, my fax machine won’t work. So I ask you, is it possible to fax over a DSL connection?

I have often seen the term Universal Plug and Play mentioned in reviews or stories, but never really understood what it referred to. Could you please explain to me exactly what Universal Plug and Play (UPnP) is and how I go about using it? Thanks.

Trying to configure a device on a network can be very confusing, particularly for someone with little or no PC-networking experience. In order to simplify this process, Universal Plug and Play (UPnP) was developed to make attaching and configuring network devices (like printers and scanners, for example) as easy as it would be to setup a new desk lamp in your office.

To accomplish this, UpnP uses a pervasive, peer-to-peer network architecture for conductivity and builds on existing Internet standards and technologies, such as TCP/IP, the Hypertext Transfer Protocol (HTTP) and the Extensible Markup Language (XML).

UPnP supports zero-configuration networking and automatic discovery, whereby a device can dynamically join a network, obtain an IP address, announce its name, convey its capabilities upon request and learn about the presence and capabilities of other devices. DHCP and DNS servers are optional and will be used if available on the network. Furthermore, a device can leave a network smoothly and automatically without leaving any unwanted state behind &#151 in other words, the network doesn’t think the device is still connected.

UPnP is very broad in scope in that it targets home networks, proximity networks, and networks in small businesses and commercial buildings. It enables data communication between any two devices under the command of any control device on the network. UPnP is an open industry standard and independent of any particular operating system, programming language or physical medium; so UPnP can work with essentially any networking media technology. This includes Cat-5Ethernet cable, Wi-Fi wireless networks, IEEE 1394 “Firewire”, phone-line and power-line networking.

UPnP involves a multi-vendor collaboration for establishing standard Device Control Protocols (DCPs). Similar to the Internet, these are contracts based on wire protocols that are declarative, expressed in XML, and communicated via HTTP. This allows for standardization on the wire, rather than in the devices.

For example, let’s say that you have a UpnP-compatible camera and printer connected to your network. The camera contains a bunch of pictures that you would like to print out. Using UpnP, you could press a button on the camera and have the camera send a “discover” request asking if there were any printers available on the network. The printer would then identify itself and send its location back to the camera in the form of a Universal Resource Locator (URL).

The camera and printer would then use the Extensible Markup Language (XML) to establish a common “protocol” to talk to each other and determine each other’s capabilities. Once those capabilities were identified, a connection would be established and the camera could communicate directly with &#151 and control &#151 the printer and print all of your photographs.

The bottom line is that theoretically, networking products that include UPnP technology will “just work” once connected to the network.

Here’s hoping.

For more information on UPnP visit the UPnP forum.

Adapted from, part of the Network.

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