How to verify speed of a 1Gb/s network?

[Rob]

gb spam wrote:
> On 4/25/06, Tim <ignored_mailbox at yahoo.com.au>
> wrote:
> 
>>For a brute force check, you could transfer a
> large number of bytes from a byte generator
> (/dev/zero?) to /dev/nul, and time it. 
> 
> To transfer 1G
> 
> One one host run
> 
>    nc -l -p 30000 > /dev/null
> 
> On the other host run
> 
>    time dd if=/dev/zero bs=1M count=1024 | nc \
>                               first-hostname 30000
> 
> Depending on your version of dd it may or may not
> display a throughput, so you may have to calculate
> it yourself freom the time displayed

Am I right, that the throughput here is 1 Giga BYTES,
which is 8 Giga bits?
On a 1 Gigabit/s network, this then should ideally
take about 8 seconds; right?

I do following:

  master$ nc -l -p 30000 > /dev/null

  slave$ /usr/bin/time -p dd if=/dev/zero bs=1M \
                count=1024 | nc master 30000

which typically prints out:

  real 16.20
  user 0.00
  sys 0.54

This means that I have effectively a network speed
of about 0.5 Gigabits/sec (as it takes 16 seconds
instead of the ideal 8 seconds).

Is my conclusion right?

Thanks,
Rob.


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