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

Andrew Pantyukhin infofarmer at
Wed Apr 26 11:04:09 UTC 2006

On 4/26/06, Rob <spamrefuse at> wrote:
> Hi,
> How can I verify that a 1Gb/s network is indeed
> operating at its optimal speed? I tried this:
> [master]$ ping -s 65507 node
> 65515 bytes from node: icmp_seq=0 ttl=64 time=1.97 ms
> 65515 bytes from node: icmp_seq=1 ttl=64 time=1.95 ms
> 65515 bytes from node: icmp_seq=2 ttl=64 time=1.94 ms
> 65515 bytes from node: icmp_seq=3 ttl=64 time=1.97 ms
> (I tried many times, over a long period of time
> to get these typical values).
> >From this I conclude that it takes about 1.95 ms
> for 65515 x 8 bits to go forth and back between
> master and node.
> Ideally, on a 1Gbit/s network, the time should be:
>   65515 x 8 x 2 / (10243) = 0.98 ms
> (x 2 for the roundtrip signal forth and back
> and 10243 is the 1G of the network)

Nopes. There's a number of 10Gig+ lines where you can't
get less than 100ms, damn the light speed :-)

ICMP echo service is pretty much always the lowest priority
of any host. I get 2000ms+ rtt from cheap d-link devices on
a gigabit network. I get 500ms+ from $10k cisco switches
on any networks.

Use iperf or other such tools for real testing.

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