Homeplug & LAN performance

[tinners]

Let me start by saying I'm no network expert.

I bought some 85Mb homeplugs, and whilst I obviously wasnt expecting 85Mb from them it looks like I am getting about 6-7Mb.

------------------------------------------------------------
Server listening on TCP port 9999
TCP window size:  8.0 KByte (default)
------------------------------------------------------------
[1912] local 192.168.1.15 port 9999 connected with 192.168.1.18 port 50274
[ ID] Interval       Transfer     Bandwidth
[1912]  0.0-600.0 sec   446 MBytes   5.9 Mbits/sec
[1912] local 192.168.1.15 port 9999 connected with 192.168.1.18 port 50275
[ ID] Interval       Transfer     Bandwidth
[1912]  0.0-600.0 sec   462 MBytes   6.2 Mbits/sec
[1912] local 192.168.1.15 port 9999 connected with 192.168.1.18 port 50283

So I thought I'd run a comparison with my wired network and between 2 ports on my router. Both ports are showing 100Mb on the router but I got this:

------------------------------------------------------------
Server listening on TCP port 5001
TCP window size:  8.0 KByte (default)
------------------------------------------------------------
[1912] local 192.168.1.15 port 5001 connected with 192.168.1.12 port 2375
[ ID] Interval       Transfer     Bandwidth
[1912]  0.0- 5.0 sec   6.8 MBytes  10.9 Mbits/sec

What does this mean ?

Is my 100Mbps network running at 10Mbps and my 85Mb homeplugs at 6Mbps ?

I just bought some 200Mb homeplugs in order to stream some video content around but they're pretty useless given these transfer rates.

Why ?

Help !

[kidzer]

I'll explain it using just the homeplug and all should become clear

The Homeplugs work at a rated speed of 85Mbps - that is 85 MegaBITS per second, file transfer and the like is usually given in speeds of Kilo/Mega/GigaBYTES per second.

So, 85Mbps is ~87040KiloBITS per second (85/1024) - to convert this to KiloBYTES, we divide by 8 - because there are 8 bits to a byte, giving us 10880 KiloBYTES per second.

This can then be converted to MegaBYTES per second by dividing by 1024 which gives us 10.625MegaBYTES per second.


...the easy way to do it is just divide by 8, which gives the same number - but hopefully that little explanation helps you in the future (if it makes sense, I can understand it - let me know if I need to be more clear!).


Although, after writing that - I see the bits you have in your post with transfer speed give speed as Mb, which renders what I've just said above...wrong I think - but the Homeplugs should have a max theoretical throughput of 10.6ish MBps, and your 100Mb ports will have a max theoretical throughput of ~12.5MBps - which fits with your findings above if the application you are using to test speeds there just has its MB/Mb mixed up - if it doesnt, then I'm wrong above (or have made an error) and you'll have to wait until someone more knoledgeable shows up to put you right!

You were ofcourse right to not expect the maximum speed advertised from your Homeplug devices, the same is true for any networking device - the data transferred between two points isn't just what the user sends/requests - it is encapsulated into a data frame for transmission across a network and so some of the avaliable bandwidth is taken for this encapsulation of your data - along with the max speed being acheived under ideal lab conditions (in most cases) - it is easy to see why you will never get use of all of the avaliable bandwidth.

Hope that helps!