Hi.

First, did you have any trouble logging on to the new forum?

Yes, I actually spoke with the tech about this, cuz I found it interesting.

He brought two gizmos with him. One (with 3 small green LED lights) plug into the wall socket (electrical outlet) under the desk, and the other end plugs into the network connection on the laptop.

I don't use this method myself, as my wireless works fine. But the laptop in the main house (where the router/gateway is located) was having problems dropping the wireless connection (.. wierd, cuz this laptop is located much closer to the router/gateway than mine).

The other gizmo plugs into a wall outlet near the router/gateway, with the network cable part of this gizmo plugged into the router/gateway.

They want you to plug the gizmo DIRECTLY into wall outlet .. and NOT a powerstrip, cuz they don't want any extra current flow thru wiring. A regular simple extension cord is also okay. A powerstrip, they say, will also work, but is less reliable, depending on number on extra current-sucking devices plugged in, and how much current these devices consume .. which can interfere with the data connection.

Devices are roughly size of a small fist. Black plastic, with some green LEDs, with 6-foot cable attached, to plug into date port. CAT-5 cabling type of stuff.

Back in the day when I used to work for Earthlink Technical Support, we pushed the powerline ethernet concept.  As previsoulys stated above, the speeds aren't by any means phenomenal, but for what an everyday user might do, substantial enough that they can be productive on the internet.

I still have a set or two around the house as a fall back if I get a computer that has questionable wireless capabilities. Nostalgic if anything else for me. Good products though.

Interesting. Could someone let me know the rate, in MB/sec, one could expect when transferring a large file between two computers on a powerline network. I assume three adapters would be needed for this test.

Dan,

I'm confused about those results. I think they are testing a single hop power line connection. One computer connected to the router by power line and the other computer connected to the router by a cable. That's my understanding. If both computers were connected to the router by power line I think the transfer rates would be slower.

MrMagoo,

Thanks for that. So I guess it still makes it one hop power line, if the one hop term is applicable. Analogous to a crossover cable between two NICs.

I'm just trying to relate it to my situation. All my computers are connected via wireless because of house design. I'd prefer cables but that's not to be. In testing, transferring a large file from one computer to another is twice as fast if one computer is connected to the router by a cable (cable lying on the floor). That's why I am curious about two hop power line. I don't need power line, I'm just curious.

Edit... I think I'm catching on. The router is irrelevant for file transfer with power line.

Dan Goodell wrote on Mar 4^th, 2009 at 11:26pm:

Not bad at all.  I'll fill in the details.

You bring up some good misunderstandings that most people have.  Most home routers are actually a 1-port router with a 4-port switch on the back.  (Although you can think of the switch connecting to an internal 'port' on the router.)  

Routers

A router can connect networks at the network layer, or layer 3 of the OSI stack.  Routers help computers on different subnets of the network talk to each other by providing a gateway (noted as the 'default gateway' in your IP settings.)  

http://en.wikipedia.org/wiki/OSI_model

More importantly to home users, these home routers also usually do Network Address Translation.  This allows you to use an address like 192.168.x.x on your computer.  An address in that range would never be seen on the public internet and for that reason can be reused in any household behind a router capable of doing NAT.  This allows you to have as many computers as you want in your house sharing internet even though your ISP most likely only gives you 1 public IP address (an IP address that IS allowed on the internet.)  Clear as mud?

Switches

The switch that you connect your computers to on the back of the 'router' works on Layer 2 of the OSI model.  Switches don't see IP addresses, only MAC addresses.  So, it is involved in one computer talking to the other within your own network.  However, it does have enough circuitry to read the MAC address and route traffic directly to the correct port on the switch that needs it.  In other words, each port has its own, isolated set of wires and circuitry and every switch port could communicate at full speed all the time.

Another device that you may still hear about but wouldn't likely buy anymore is a hub.  Hubs actually work at layer 1 - the physical layer.  They only connect the wires together - like a really sophisticated splice of all your cables.  

This means that the entire network is shared between all the computers connected to a hub - as opposed to on a switch where each computer has its own dedicated segment on the network.  This allows computers on switch to use full duplex communication (that is, they can talk and listen at the same time.)  Computers connected to a hub must use half duplex since every computer hears what ever computer says - even themselves.  That makes shared mediums like hubs slower networks (and more prone to error.)

Wireless

The wireless access point is almost like hub connected to the switch (but without wires, obviously.)  The logical difference is that the wireless access point is smart enough to keep track of the different nodes that are connected to it and provide encryption, while a hub is a completely dumb device.  This is a big part of the reason you never get the advertised speeds on a wireless network.  It is a shared network.  

The other reason wireless networks are slow is that the top speed is measured by burst speeds, and the bursts are very short (a few tens of miliseconds.)  That's why wireless networks do fine with small amounts of data like web browsing but choke up with something like a large file transfer.

Powerline

Now, a bridge can be thought of as a 2-port switch.  In this case, each side of the switch connects to a different kind of network (so it bridges two dissimilar networks.)  One switch port goes to an ethernet network (your computer, router, or a bigger switch or router if you want to do that.)  The other 'port' goes to the powerline network.

The powerline network is a shared medium.  All the computers on the powerline network are sharing the same wires (or they couldn't communicate.)  So we are in the same situation as the hub, only the splicing is done at your electrical box instead of in a nice hub.

Powerline networking also has to contend with the fact that those wires were never meant to carry data traffic.  There is often more than one isolated power leg in your house, and outlets on different legs will likely not be able to communicate.  Also, there is a lot of wire there that you don't need.  An ethernet cable is going to go straight from source to destination.  Your electrical cables go to every switch and outlet in the house.  Now, add to the fact that there is noise from both electricity and every radio signal any wire in the house happens to pick up, and you have a hostile environment for data.

With that in mind, they work pretty well.  Like Dan said, sometimes ethernet and wireless are both not options for whatever reason, and powerline will get the job done.  

There is also a similar technology (HPNA) that allows you to use your phone lines to connect computers.  It works better than powerline (since phone lines are better suited to carrying data than electrical cable,) but is usually at least twice as expensive.  Home Phoneline Network Alliance gear really comes in handy for its range.  Phone lines will get you up to 1000 ft, and similar gear will give you several thousand feet over coax, so it will really get to the back corners of your mansion like wireless couldn't dream of.  Speeds are decent, too, advertised up to 320 Mb/s.

http://en.wikipedia.org/wiki/HomePNA

For Price/Performance, there is still nothing that beats Cat5 and Ethernet.  If you can get a wire, you should.

Incredibly interesting information!