Powerline between mmodem and router

For historical reasons, our Virgin cable internet comes into the house upstairs. I also had the wireless router up there but coverage at the back of the house was poor. So I eventually movde the router to the middle of the house and used an 85Mbs powerline link (Belkin) to connect the router downstairs and the modem upstairs. It has completely solved the wireless strength issues bothe upstairs and downstairs.

Now, the question is - naturally the 85Mbs rating of the powerline link is likely to be theoretcial only. I'm trying to figure out what a realistic bandwidth for this arrangement is because if it's only 15Mbs, for example, then even my 20Mbs Virgin connection may be slightly compromised (I get around 13Mbs on speed tests and the cabinet is obly 60 yards from the house). In which case there is probably no point in upgrading to the improved virgin 30Mbs option.

Can anyone suggest a way of working out what's what?

Ian

Are you doing the speedtest wired or wireless?

If wireless then you need to repeat it with a wired connection. If then gives a similar result then possibly the powerline adapter is a problem.

If already wired, you need to try connecting the PC directly to the modem, or moving the router next to the modem and trying again. If you get better speeds - powerline is a problem, same speed then maybe something else is causing the loss of 5Mbps.

Did you get a CD with the adapters?

The Solwise and Maplin-no-name ones I have bought have come with a utility that displays the link speed between your "local" adapter, and any others on the network.

You could try the utilities here, see if they work. (Lots of the 85Mbps ones share the same chipset).

http://www.solwise.co.uk/net-powerline-pl-85pe.htm

"naturally the 85Mbs rating of the powerline link is likely to be theoretcial only. I'm trying to figure out what a realistic bandwidth for this arrangement is because if it's only 15Mbs"

I'm using similar Power-Line technology too, my 85Mbps power-line plugs consistently give me around 65-75Mbps speed and they are sharing between 2 PCs. You may need to check that:

a) your Power-line plugs are plugged straight into your wall sockets or may through a more direct "extension adapter" and NEVER via a cabled extension pad (IF you have to extend your mains as well). Connecting your Power-line plugs directly on to your wall-sockets being used is the KEY to improve their bandwidths or speed as extended power-extensions would cause unmatched transmissions between power-line adapters, causing speed lost through errors during transmissions.
b) ensuring that ALL your Power-line Adapters are plugged into the SAME mains node, i.e. power-sockets in your house controlling by the same Circuit-Breaker or Fuse-Box. OR
b) alternatively, use 200Mpbs power-line adapters instead to improve further your speed.

However, improving options a) & b) are a must for either 85Mbps or 200Mbps adapters.

Some great advice and suggestions, thanks!

Ian

In my experience the quoted connection speed from the software bares no resemblance to the actual throughput speed.
My Devolo 200's report a link of around 180 but actual measured throughput is around 30 to 35.
My 85's only achieved around 15 to 20 despite indicating a connection speed of 70 or so.

Easiest way to check real speeds is a file transfer between two pc's at each end of the link.

Gary

Would be shocked if 85Meg units were transferring in one direction at 65 to 75Meg.

Generally it is divide by two, then allow for the attenuation of the mains cables.

You can actually find out quite a lot of information about the modulation (which is negotiated during use) of most devices. That information, with ethernet+IP+TCP overheads subtracted, gives a much more realistic view of the likely throughput of the devices.

Probably the software that the manufacturer of your device supplied gives some overview of this data, but there's also an opensource utility called Faifa, which can give you really detailed raw information from the devices. It ships with Debian/Ubuntu these days, but it can also be downloaded from https://dev.open-plc.org/

Edit: Whoops just saw the other branch of this thread, seems I was a little slow there! The opensource tool is vastly better than any of the windows utilities I've seen so far though.

Edited by deleted (Mon 28-Feb-11 15:55:55)

It is both "both directions" I believed according to the manufacturer's own system tool provided, bearing in mind that it were the "physical-layer's bandwidth" so the actual real-life throughput would be less than that after counting out the overheads as you may have awared.
Thanks

In reply to a post by gmoorc:

In my experience the quoted connection speed from the software bares no resemblance to the actual throughput speed.
My Devolo 200's report a link of around 180 but actual measured throughput is around 30 to 35.
My 85's only achieved around 15 to 20 despite indicating a connection speed of 70 or so.

Easiest way to check real speeds is a file transfer between two pc's at each end of the link.

Gary

I have now had a chance to test with and without the powerline bridge. And I moved the upstairs powerline module to its own wall socket from an extension block (I knew at the time of installation that this was not ideal, but it mean a lot of faffing around in the room.) Moving the module probably improved the speeds I was getting by 2Mbs from about 11Mbs to 13Mbs. This was over wireless-n from about 20 feet from the router. Connecting directly to the router improved things to around 15Mbs (and wireless next to the router was about the same).

I then moved the router upstairs and plugged straight into the modem. I was now getting 19.5Mbs (on a 20Mbs Virgin XL connection), so that answers my question. The 85Mbs powerline bridge is good for about 15Mbs real world speed in my particular home mains setup. I do have access to some 200Mbs powerline modules and will try them out some time in the future. But for now there is no point in me upgrading to Virgin's 30Mbs option.

Ian