To Find full or half duplex speed:
You can use dmesg command to find out your duplex mode:
# dmesg | grep -i duplex
O/P:
eth0: link up, 1000Mbps, full-duplex, lpa 0x45E1
So we can come to know that it has
1. One NIC card, i.e, etho. if it has 2 NIC cards , it will show eth1
2. It is 1000Mbps speed
3. Communication is full duplex mode.
Use ethtool to display or change ethernet card settings. To display duplex speed.
# ethtool eth0
Output:
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: 1000Mb/s
Duplex: Full
Port: Twisted Pair
PHYAD: 0
Transceiver: internal
Auto-negotiation: on
Supports Wake-on: umbg
Wake-on: g
Current message level: 0x00000007 (7)
Link detected: yes
Explanation:
So we come to know that , eth0 supports 10baseT/Half, 10baseT/Full, 100baseT/Half, 100baseT/Full and 1000baseT/Full.
But the network configured as 1000Mbps , Full duplex mode.
We can also use mii-tool to find out your duplex mode. Type following command at shell prompt:
# mii-tool
Output:
eth0: negotiated 100baseTx-FD flow-control, link ok
Remember:
100baseTx-FD: 100Mbps full duplex (FD)
100baseTx-HD: 100Mbps half duplex (HD)
10baseT-FD: 10Mbps full duplex (FD)
10baseT-HD: 10Mbps half duplex (HD)
