[nzlug] puzzling network prob between two linux boxes on home network

[Nick 'Zaf' Clifford]

You are measuring apples and oranges.

I'd suggest getting box A and box B next to each other and trying a
speed test with cross-over cable.
Then plug them both into the cheap dlink switch, then them into either
end of the homeplug device.

Also, Box B thinks it has a 100Mbps connection because it does, the
connection between the cheap switch and Box B is a 100mbit connection.
The link speed doesn't indicate its overall speed, just the speed
between the two devices (you may already know this, but I wasn't sure if
you were noting the 100Mbps because you thought it should indicate
slower/faster).

My suspicion is already on the cheap Belkin or DLink, simply because my
experience is that the more obscure or weird the networking problem, the
more likely it is the hardware.

I don't trust those Internet Speedtest results, so do your own local
tests. Also, don't forget that the 4mbps it claims is download only. If
you are getting 4mbps up, I wanna know who your ISP is :)

If you have a third box (Box C) you can plug in, then test that too.

Oh, and one more thing, make *SURE* that every test is either in Bits
per second or bytes per second, and don't mix them up. Often people look
at the download rate of a file and forget its usually (but not always!)
Bytes per second.

Nick


stephen wrote:
> I have a little networking mystery which is driving me nuts.
>
> Box A is connected directly via ethernet to my (cheap Belkin) router.
> The router and Box A both think they have a 100Mbps full duplex link (as
> reported by ethtool eth0 on Box A, status lights on the router).
>
> Box B is connected via ethernet to a cheap Dlink switch, which in turn
> is connected to a LAN over power (you know, Homeplug) dongle, with the
> remote dongle going to the router. Box B and the switch both think they
> have a 100Mbps full duplex link. Homeplug is supposed to be 85 Mbps in
> theory, and anecdotally I hear it should be good for 10 anyway.
>
> Box B, despite the suboptimal adhoc set of links, can max out my 4 Mbps
> cable connection, as reported by various DSL speed test sites. So can
> Box A.
>
> However, I can not get better that about 1.5 Mbps from box A to box B
> (measured with a very large file served by Apache on box B, and wget on
> box A). Sometimes it is as low as 0.9 Mbps.
>
> I have swapped cables. I have tried wireless on Box A (the router is
> also 801.11g capable). I have restarted the router, restarted the switch
> and jiggled the Homeplug dongles. No change.
>
> So, to recap, both these boxes can do at least 4 Mbps to the internet,
> but they can't manage even half that to each other.
>
> I had intended that Box B, which is in a nice quiet room upstairs,
> become a server for media files and for backups, but I want much better
> bandwidth for that.
>
> Suggestions for poking around?
>
> Stephen
>
>
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