Q. How do I find out my NIC speed in Linux ?
A. Use ethtool or mii-tool to display or change ethernet card settings.
ethtool
To display duplex speed of eth0, type the following command
# ethtool eth0
Sample outputs
Settings for eth0:
Supported ports: [ TP ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Supports auto-negotiation: Yes
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Advertised auto-negotiation: Yes
Speed: 100Mb/s
Duplex: Full
Port: Twisted Pair
PHYAD: 1
Transceiver: internal
Auto-negotiation: on
Supports Wake-on: pumbg
Wake-on: g
Current message level: 0x00000001 (1)
Link detected: yes
mii-tool
To display duplex speed of eth0, type the following command
# mii-tool -v eth0
Sample outputs
SIOCGMIIREG on eth0 failed: Input/output error eth0: negotiated 100baseTx-FD, link ok product info: vendor 00:50:43, model 11 rev 1 basic mode: autonegotiation enabled basic status: autonegotiation complete, link ok capabilities: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD advertising: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD flow-control link partner: 100baseT4 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD
Where,
100baseTx-FD: 100Mbps full duplex (FD)
100baseTx-HD: 100Mbps half duplex (HD)
10baseT-FD: 10Mbps full duplex (FD)
10baseT-HD: 10Mbps half duplex (HD)