It has been a very long time since I looked at the LPI (training, courseware, materials, exams), and I don’t remember if this is even covered in LPI 101/102 (and I have no idea about Level 2 or 3, I’m only Level 1 compliant, and even then, back in the Red Hat 7.2 study days :P). Either way, I hope this note is useful. So, how do you check (or change) the speed of your Ethernet card?
Quite simply, with the help of ethtool. Some might be saying, why not mii-tool – well, its because mii-tool is now obsolete, though you pretty much have it on all your Linux distributions. Why? Because it comes as part of net-tools, which also provides other useful tools like netstat, route, ifconfig, arp and many more. If you don’t have ethtool installed, its available in a package, aptly titled, ethtool.
Usage is simple: ethtool eth0. Replacing eth0 with whatever your interface is, is fine. You should now be able to see the speed of your link, and if you were for instance changing it, you might do ethtool -s eth0 speed 10 duplex half or something similar (read the man page, its really helpful).
Me? I just wanted to see if I connected myself to a 100mbps switch or a 10mbps switch and was too lazy to look at the wiring closet ;)
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