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-   -   Network speed mystery (http://www.hardwarecanucks.com/forum/networking/57105-network-speed-mystery.html)

Chris October 6, 2012 06:04 AM

Network speed mystery
 
2 types of powerline adapter:

TPL-401E
500 Mbps powerline
10/100/1000 Mbps ethernet

TPL-406E
500 Mbps powerline
10/100 Mbps ethernet

The mystery for me is the 406E. It has 500 Mbps powerline but the ethernet which is used to connect to pc is only 100 Mbps. How can it achieve 500 Mbps speed (in ideal conditions)? Would the ethernet limit it to 100Mbps?

I actually have a pair of 401E and the actual speed is bout 200 Mbps while the 406E working in the same location would only give me about 150 Mbps. So is the 406E being limited by the 10/100 ethernet connection?

Please enlighten me. Thanks.

Arinoth October 6, 2012 08:03 AM

Well that's because that's 500 Mbps over your power line, which technically are thicker (lower cage wires) so they can handle a lot more bandwidth or current compared to your smaller twisted pair CAT cables.

Chris October 6, 2012 08:19 AM

What I do not understand is:
406E has 10/100 ethernet connection to pc. Does it limit the speed to 100 Mbps?

Perineum October 6, 2012 10:32 AM

yes it does. change the cable from the adapter to the computer.

Chris October 6, 2012 10:38 AM

Change the cable? They are all cat5e. The 401E says it can do 10/100/1000 but the 406E says it can only do 10/100.

Shadowmeph October 6, 2012 11:45 AM

Quote:

Originally Posted by Perineum (Post 660222)
yes it does. change the cable from the adapter to the computer.

I am not sure that that would do anything unless the cable is faulty.

Ardric October 6, 2012 12:35 PM

Trendnet figures that some customers will run a LAN with more than two nodes. Someone might choose to use a 500 Mbps adapter with gig ethernet at their router and home server, another gig-capable adapter at their office PC, and a 100Mbps max "nano" adapter for the HTPC and the kid's PC and etc. All of these adapters talk to each other using the same 500 Mbps modulation scheme.

They call it 200 Mbps* on their spec sheet. Of course it's 100base-T, which is 250 MHz signalling, 125 Mbaud, 100 Mbps after coding, and full duplex, which means it's 100 Mbps each way at the same time. It's kinda lame to say full duplex = 2x speed, but that's what marketing does these days. Likewise there's not much chance you'll ever get a real 500 Mbps out of the units with gig ports. The adapters are a sort of radio and modem combo to modulate the signal on the power lines, and like wifi the speed they make in the real world is dependent on the radio environment on the power lines they have to work with.

Quote:

Well that's because that's 500 Mbps over your power line, which technically are thicker (lower cage wires) so they can handle a lot more bandwidth or current compared to your smaller twisted pair CAT cables.
Power line is thicker, lower gauge wire, so it can carry a lot more current, but current capacity and bandwidth potential are not related much at all. The power lines are in practice a much worse enviornment than your usual CAT5 cable because of a whole bunch of reasons, like instead of point-to-point it's tapped cables in a weird forking topology that causes reflections and ringing, power lines are loaded up with all sorts of major noise sources driving the cable with low impedance, there's been no attempt made to balance the cable impedance or maintain an even twist rate, etc etc. That's why the power line adapters are designed more like wifi adapters than simple NIC cards... because they really have to work hard (DSP) for that 500 Mbps.

Chris October 6, 2012 07:15 PM

Thanks Ardric for your detailed explanation. As I mentioned before, I did get about 200 Mbps from the units with gig port (401E), but about 150 Mbps from the 406E. I will keep the 406E unit since it is used for my older pc used for watching video streaming from the internet.


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