Using the ethtool command by example

ethtool The command is used to display / Change Ethernet adapter settings . You can go to Linux Use this tool to change the network card speed 、 Automatic negotiation 、LAN Wake up settings 、 Duplex mode . In this paper , I'll show you some ways to help you solve the problem of Ethernet card ethtool Order sample .

1) Display Ethernet interface details

ethtool The command retrieves the status of the Ethernet interface . The output shows etho The speed of the interface 、 Duplex 、 Properties such as status and wake-up .

Here is an example ：

# ethtool eth0

Settings for eth0:

Supported ports: [ TP ]

Supported link modes: 10baseT/Half 10baseT/Full

100baseT/Half 100baseT/Full

Supports auto-negotiation: Yes

Advertised link modes: 10baseT/Half 10baseT/Full

100baseT/Half 100baseT/Full

Advertised auto-negotiation: Yes

Speed: 1000Mb/s

Duplex: Full

Port: Twisted Pair

PHYAD: 1

Transceiver: internal

Auto-negotiation: on

Supports Wake-on: d

Wake-on: d

Current message level: 0x00000007 (7)

Link detected: yes

There are three types of duplex ：

full duplex ： Use when Ethernet is connected to the switch . Allow bidirectional transmission , That is, send and receive data packets at the same time .

Half duplex ： Use when Ethernet is connected to the hub . Only one-way transmission is allowed , That is, send or receive data packets .

Automatic negotiation ： According to the network connection , Ethernet interface decides whether to use full duplex or half duplex .

2) ETHTOOL_OPTS Variable

have access to Ethtool_opt Variables are permanently set Ethtool Command settings . Let's take a look at the example given below ：

# vi /etc/sysconfig/network-scripts/ifcfg-eth0

DEVICE=eth0

BOOTPROTO=static

ONBOOT=yes

ETHTOOL_OPTS="speed 50 duplex full autoneg off"

You can use ifup and ifdown Command to test the above settings .

3) Show statistics

You can use the following commands to check Ethernet driver settings and auto negotiation ：

# ethtool -i eth0

driver: bnx2

version: 2.0.1-suse

firmware-version: 1.9.3

bus-info: 0000:04:00.0

[[email protected] ~]# ethtool –a eth0

Pause parameters for eth0:

Autonegotiate: on

RX: on

TX: on

Ethtool Ordered “-p Options ” Helps identify specific devices from multiple devices .

# ethtool –p eth0

Having network card statistics is very useful for solving network problems .

# ethtool –S eth0

NIC statistics:

tx_packets: 148683

rx_packets: 179489

tx_errors: 0

rx_errors: 0

rx_missed: 0

align_errors: 0

tx_single_collisions: 0

tx_multi_collisions: 0

unicast: 116884

broadcast: 25361

multicast: 61674

tx_aborted: 0

tx_underrun: 0

The above output shows the details about transmitting and receiving packets .

4) Enable flow control

In the latest MAC and GMAC Embedded devices , Can pass “PAUSE” Parameter enable full duplex flow control .

This is the solution ：

# ethtool -A eth0 [autoneg on|off] [rx on|off] [tx on|off]

The details of the uninstall parameters are as follows ：

# ethtool –k eth0

however , Any changes made to the Ethernet parameter settings will disappear at the next startup . To keep them intact the next time they start , You must add commands to /etc/rc.local Make these changes permanent

# cat /etc/rc.local

ethtool -s eth0 speed 100 duplex full autoneg on 1>/dev/null 2>/dev/null

ethtool -s eth1 speed 100 duplex full autoneg on 1>/dev/null 2>/dev/null

5) Set duplex mode

The following example shows how to use ethtool Command to set speed or duplex mode , As shown below ：

# ethtool -s eth0 speed 100 duplex full

# ethtool -s eth0 speed 10 duplex half