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

Chris Howells howells at
Wed Apr 26 09:44:12 UTC 2006

Rob wrote:

> How can I verify that a 1Gb/s network is indeed
> operating at its optimal speed? I tried this:

By transferring large amounts of data using a light-weight protocol 
(maybe FTP) and timing the amount of time it takes.

Also various testing utilities, for instance ttcp.

> [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

This is a measure of latency only.

For instance, I can easily get 10ms pings on 512kbit/sec ADSL. It can 
only transfer data at ~60 KB/sec though.

I can get these values on a very lightly loaded 100Mbit/sec network:

chris at merlin$ ping
PING ( 56 data bytes
64 bytes from icmp_seq=0 ttl=128 time=0.844 ms
64 bytes from icmp_seq=1 ttl=128 time=0.740 ms

> PS: I verified my calculation method for two
> computers here on a 100Mbit/s network, from which
> I get:
>    time with ping: 12.4 ms
>    ideal calculated time: 10 ms

Sounds like your 100Mbit/s network is very heavily loaded, you would 
expect ~1ms pings.

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