[gentoo-user] Re: Network collisions

[James]

Dave Oxley <dave <at> daveoxley.co.uk> writes:


> Yeah, its a hub. I'll stop trying to set it to full duplex now.

> It is 40 times quicker in one direction than the other. Can you
> give me a hint where to go from here.

Try connecting the 2 systems  with only a 'cross-over cable' run the applications
and make measurements. If this results in an increase in the bandwidth 
in either direction, you may want to put systems back on the hub, and 
have a third system run ethereal. Look at your data traffic and see 
if anythingelse is using the bandwidth from either of these 2 system 
or what else is plug into the hub/switch.

Is the hub a 10Mbps only hub/switch, check that. On 10 Mbps ethernet 
hubs,you can never reach the full 10 Mbps, in fact with many systems 
chattering,the practical throughput is marginally around 33%.

If when you are on the cross over cable and you get similar poor 
results,then the problem may be in the ethernet driver code, 
kernel, irq settings or
some other low level part of the kernel/modules, especially if 
you get the same skewed results with several different 
applications moving data between the systems. But, if when
 you move data between these 2 isolated system, and 
get different bandwidth performance semantics, then the problem 
is most likely between the applications or a bottleneck in the 
application code (poor data structure for example).

Make sure you computers are not resource limited, thus blocking 
the processthat you are running to move the data. Top and ntop 
are just a few toolsto help track down these sort of issues.

Sadly, you may have a complex mix of part or all of these 
aforementioned issues... 

hth,
James

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