Linux - Lan card set up full duplex half duplex mode, Mii-tool command to set up full duplex mode

Lan card set up full duplex half duplex mode

How do find my eth card or Network interface card (NIC) is working at full duplex or half duplex mode?

How to change my eth card from half duplex to full duplex?

Normally we use the term eth card or NIC for LAN card which is use to send and receive or transfer data. Full duplex means you are able to send and receive data simultaneously. In half duplex, you can either send or receive data at a time (i.e. you cannot send receive data simultaneously). Full duplex gives you better performace and speed. Spped is considered as one of the main factor when it comes to data transfer and from the above it is clear that full duplex performs better than the half duplex.

 # dmesg | grep -i duplex

Output:

eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: None
eth1 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: None

ethtool:Command to find the speed and full duplex or half duplex

 # ethtool eth1

OUTPUT:
Settings for eth1:
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: d
Wake-on: d
Current message level: 0x00000007 (7)
Link detected: yes

mii-tool:Command to check the speed and duplex mode

 # mii-tool eth1

OUTPUT:

 eth1: negotiated 100baseTx-FD, link ok

Note, below is used with mii-tool to set speed and duplex

100baseTx-FD: 100Mbps full duplex (FD)
100baseTx-HD: 100Mbps half duplex (HD)

10baseT-FD: 10Mbps full duplex (FD)
10baseT-HD: 10Mbps half duplex (HD)

How to change from half duplex to full duplex with 100Mbps speed

 # mii-tool -F 100baseTx-FD

Setup 10Mbps half duplex:

 # mii-tool -F 10baseT-HD

# mii-tool eth1

OUTPUT:
  eth1: 100 Mbit, full duplex, link ok

This are the commands used in linux to set your LAN or ethernet card in full duplex or half duplex mode. MII stands for Media Independent Interface (MII) unit, MII is used by most of the fast or very fast ethernet and it is not supported for old cards for old card you can try with dmesg. You can also use ethtool to sep up spped and duplex.

# ethtool -s eth1 speed 100 duplex full

# ethtool -s eth1 speed 10 duplex half

The topic on Linux - Lan card set up full duplex half duplex mode is posted by - Math

Hope you have enjoyed, Linux - Lan card set up full duplex half duplex modeThanks for your time