Can´t get Gigabit connection?

Do you get 100Mbps link speed when you expected Gigabit?

In my experience, it´s always the cable to blame, 9 times out of ten. The tenth time, it´s the auto-negotiation that failed.  Could be solved by unplugging and plugging in the cable again, but most commonly you should switch to a quality cable.

How do you check the link-speed in Ubuntu

verify your ethernet settings (replace eth0 with your ethernet device name – use ifconfig if unsure)

sudo dmesg |grep eth0

you can also install mii-tool and try this

mii-tool -v  eth0

or install ethtool (best) and try

ethtool eth0

Checking actual throughput

use the tool iperf

On one end, start a server:

iperf -s
Server listening on TCP port 5001 
TCP window size: 85.3 KByte (default) 

On the other end

iperf -c
Client connecting to, TCP port 5001 
TCP window size: 85.0 KByte (default) 
[ 3] local port 39994 connected with port 5001 
[ ID] Interval Transfer Bandwidth 
[ 3] 0.0-10.0 sec 1.09 GBytes 936 Mbits/sec

How do you check the link speed in OSX

Start the “Network Utility” appliction

Look at the Info tab, select Ethernet (en0) entry.

See the Link Speed

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