Linux – How to Verify the Speed of a NIC Using Ethtool

ethtoolgigabit-ethernetlinux

I just installed a new gigabit network interface card (NIC) in Linux. How do I tell if it is really set to gigabit speeds? I see ethtool has an option to set the speed, but I can't seem to figure out how to report its current speed.

Best Answer

Just use a command like: ethtool eth0 to get the needed info. Ex:

$ sudo ethtool eth0 | grep Speed

Speed: 1000Mb/s

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How to get gigabit network speeds on Windows XP

I would try booting the Windows machine with a bootable Linux CD like Ubuntu, and check the statistics there, to exclude the possible Hardware issues.

Linux – Having an issue trying to get Gigabit speed across the network (Ubuntu Server)

As @Luis pointed out, 'b' = bit, and 'B' = byte. iperf helps us out by reporting times in Mbits/sec:

[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec  1.01 GBytes   865 Mbits/sec

Does ifconfig eth0 show any errors on either host? From your reports, it seems as if either the CPU is overloaded on one of the two iperf machines, or the switch (please tell me it's not multiple switches) between them is overloaded, or you have a 100Mbit constriction somewhere between your hosts. I've found people cascaded off of a small 100Mbit switch one too many times, so it's good to know where your cable runs start and finish. Are you using a smart switch? Does it show that your ports are active at gigabit speeds?

Once you figure out your problem, you might want to enable jumbo frames on your hosts in order to get even better throughput when you're making bulk data transfers, provided you have a reasonably-modern switch.

Best Answer

Related Solutions

How to get gigabit network speeds on Windows XP

Linux – Having an issue trying to get Gigabit speed across the network (Ubuntu Server)

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