Homeplug compability problem - SMC 14 Mbps vs Edimax 85 Mbps

Hi! I have been using four SMC homeplug 14 Mbps units at home, and this has been working great. The only problem is that 14 Mbps is not good enough for streaming video etc from one pc to another. Therefore, I just bought two new units, but this time it was Edimax 85 Mbps. The boxed look almost identical, so I guessed it was the same content but upgraded to 85 Mbps and with different branding.

When replacing one of the old SMC boxes with the new Edimax unit, the Edimax apparently could not communicate with the remaining SMC units. In fact, it seemed as if I the SMC units stopped working after I plug in the Edimax unit.. Anyone have any experience or knowledge about this? Is there some reason why these two cant be used along each other?

Regards, Per Magnus

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Does the Edimax unit support *HomePlug* standards? The SMC units will only work at that speed.

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"Perma" hath wroth:

I have a few of those 14Mbit/sec SMC EZ-Connect Ethernet boxes I picked up cheap. Everything slows down when I turn on the shop flourescent lights and stops when I run the vacuum cleaner. Interestingly, there's no effect from other motors in the house. We have 6 houses on our AC power transformer and the boxes work between any of these house.

Have you actually measured your delivered thruput? Try IPerf:

Setup two machines. One one, run the server part as: iperf -s On the other, run the client as: iperf -c ip_address_of_server_machine I get about 5 Mbits/sec on the SMC's when things are working and about half that when the noisy lights are running.

You should see about 20-25Mbits/sec with your 85Mbit/sec units.

Nope. Different chipsets. I forgot if they use Intellon, Connexant, Arkados, or Maxim chips. Probably Intellon.


Both technologies use the same 2-28MHz frequency range on the power line but with radically different modulation characteristics. More simply, they interfere with each other. There is no downward compatibility from the new AV 200Mbit/sec to 85Mbits to 14Mbits/sec. It is compatible with BPL (broadband powerline) systems.

This may help explain things:

Note that neither Edimax or SMC are listed as HomePlug compliant:

However, they may have private labelled a complaint product. Dunno for sure.

I couldn't find an 85Mbit/sec product on the Edimax web site. Is there some reason that you didn't bother to disclose any model numbers?

Some light reading:

Incidentally, this is a wireless networking newsgroup. You might try searching for a more appropriate group, blog, or mailing list.

Reply to
Jeff Liebermann

Thank you for great response, Jeff! That explains why I was experiencing the problems...

The diagnostics util which follows SMC seems to display speeds up to

11 Mbit/s, but haven't really tried Iperf. I have only experienced that music streams ok, and that video files (divx) seem to be lagging sometimes. Therefore the upgrade to 85Mbit..

The Edimax unit I am using is: Edimax, HP-8500 HomePlug Ethernet Bridge 85MB

I guess I'll just have to upgrade the whole lot of units, then, since they dont work alongside.


-Per Magnus

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You may actually be able to use them both at the same time, just not see each other.. I have both a few (netgear) 14 Mbps units AND a Netgear 85 Mbps on the system at the same time... One (the slower) for sharing small files and music, and the other higher speed one for video files (My toshiba/Tivo records and stores programs on my network storage.). Point is it is possible, just don't know if it is possible with those specific devices I have one unit of each speed plugged into my wap/router and the ac, and can go anywhere in the house and get whatever speed the unit does when I plug it in... FWIW Netgear also makes a 200 Mbps device (however for Gigabit ethernet devices), but the fact that powerline can do 200 Mbps with those, says to me you sure should be able to do powerline with combinations of slower stuff that add up to less than 200...

Perma wrote:

Reply to
Peter Pan

On Sun, 04 Feb 2007 16:57:32 -0800, Jeff Liebermann wrote in :

Have you tried RFI filters?


HomePlug AV co-exists with HomePlug 1.0.

Also, 100 Mbps is a more meaningful characterization of HomePlug AV:

HomePlug AV has pushed Shannon's Law to its limit and provides a 200Mbps class service at the PHY layer. After overhead considerations, the MAC layer will support over 100Mbps.

Reply to
John Navas

John Navas hath wroth:

No. That would be too easy. It's more fun to complain.

My whole house is one big source of RFI and EMI. Ham radio, test equipment, assorted motors, computahs, etc. Some big ferrite beads would probably solve the flouresent light problem. I have a nicely filtered portable power test box. I'll try it on the vacuum cleaner when I get inspired to clean house.

Maybe something like these if I can't find any big ferrite beads in my junk box:

Reply to
Jeff Liebermann

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