一、ethtool

ethtool is used to query and control network device driver and hardware settings, particularly for wired Ethernet devices.

devname is the name of the network device on which ethtool should operate.

man 文档
参考

1.1 常见操作

1.1.1 展示设备属性

# root@ubuntu:~# ifconfig
eno1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
docker0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536

# ethtool eno1
Settings for eno1:
	Supported ports: [ TP	 MII ]
	Supported link modes:   10baseT/Half 10baseT/Full
	                        100baseT/Half 100baseT/Full
	                        1000baseT/Full
	Supported pause frame use: Symmetric Receive-only
	Supports auto-negotiation: Yes
	Supported FEC modes: Not reported
	Advertised link modes:  10baseT/Half 10baseT/Full
	                        100baseT/Half 100baseT/Full
	                        1000baseT/Full
	Advertised pause frame use: Symmetric Receive-only
	Advertised auto-negotiation: Yes
	Advertised FEC modes: Not reported
	Speed: Unknown!
	Duplex: Unknown! (255)
	Auto-negotiation: on
	master-slave cfg: preferred slave
	master-slave status: unknown
	Port: Twisted Pair
	PHYAD: 0
	Transceiver: external
	MDI-X: Unknown
	Supports Wake-on: pumbg
	Wake-on: d
	Link detected: no

# ethtool docker0
Settings for docker0:
	Supported ports: [  ]
	Supported link modes:   Not reported
	Supported pause frame use: No
	Supports auto-negotiation: No
	Supported FEC modes: Not reported
	Advertised link modes:  Not reported
	Advertised pause frame use: No
	Advertised auto-negotiation: No
	Advertised FEC modes: Not reported
	Speed: 10000Mb/s
	Duplex: Unknown! (255)
	Auto-negotiation: off
	Port: Other
	PHYAD: 0
	Transceiver: internal
	Link detected: yes

# ethtool lo
Settings for lo:
	Link detected: yes

其中全双工、半双工、自动协商的区别如下：

• Full duplex : Enables sending and receiving of packets at the same time. This mode is used when the ethernet device is connected to a switch（交换机）.
• Half duplex : Enables either sending or receiving of packets at a single point of time. This mode is used when the ethernet device is connected to a hub（集线器）.
• Auto-negotiation : If enabled, the ethernet device itself decides whether to use either full duplex or half duplex based on the network the ethernet device attached to.

1.1.2 改变网卡属性

1.1.2.1 Auto-negotiation

上文展示的 Auto-negotiation 为 true，可通过 -s autoneg 关闭它。

# ifdown eth0
    eth0      device: Broadcom Corporation NetXtreme II BCM5709 Gigabit Ethernet (rev 20)
    eth0      configuration: eth-bus-pci-0000:0b:00.0

# ethtool -s eth0 autoneg off # -s 指定网卡名称, 设置 autoneg = off

# ethtool eno1
Settings for eno1:
	Supported ports: [ TP	 MII ]
	Supported link modes:   10baseT/Half 10baseT/Full
	                        100baseT/Half 100baseT/Full
	                        1000baseT/Full
	。。。
	Auto-negotiation: off # 此处信息已变为 off
	Link detected: down # 此处信息已变为 down

# ifup eno1

1.1.2.2 Speed

改变网卡速度，注意不要设置超过网卡的 limited capacity

# ethtool eth0 | grep Speed
	Speed: 1000Mb/s

# ethtool -s eth0 speed 100 autoneg off

# ethtool eth0 | grep Speed
	Speed: Unknown! (65535) # 注意：如果网卡在 online 时，被改了 speed 则会自动变为 offline，此时需要手动 ifup

# ifup eth0
    eth0      device: Broadcom Corporation NetXtreme II BCM5709 Gigabit Ethernet (rev 20)
    eth0      configuration: eth-bus-pci-0000:0b:00.0
	Checking for network time protocol daemon (NTPD):                     running

# ethtool eth0 | grep Speed
	Speed: 100Mb/s

# 可看到设置后从 1000Mb/s 变为 100Mb/s

可通过 ifconfig 设置 MTU

1.1.3 展示网卡驱动设置

# ethtool  -i eno1
driver: r8169
version: 5.19.1-051901-generic
firmware-version: rtl8168h-2_0.0.2 02/26/15
expansion-rom-version:
bus-info: 0000:59:00.0
supports-statistics: yes
supports-test: no
supports-eeprom-access: no
supports-register-dump: yes
supports-priv-flags: no

1.1.4 只展示 Auto-negotiation, RX and TX

# ethtool -a eno1
Pause parameters for eno1:
Autonegotiate:	on
RX:		off
TX:		off

# 参数含义如下：
-a --show-pause
        Queries the specified Ethernet device for pause parameter information.

1.1.5 展示统计

# ethtool -S eno1
NIC statistics:
     tx_packets: 6199
     rx_packets: 16548
     tx_errors: 0
     rx_errors: 1
     rx_missed: 0
     align_errors: 0
     tx_single_collisions: 0
     tx_multi_collisions: 0
     unicast: 4228
     broadcast: 10859
     multicast: 1461
     tx_aborted: 0
     tx_underrun: 0

1.1.7 排除网络故障

连接成功后，我们期望 Speed 是明确的值，Duplex 是 Full/Half，Link detection 是 Yes。如果不是（如Speed、Duplex 为 Unknow 时，Link detection 为 No 时），可能交换机或网络设置有问题。

此时可以用 tcpdump 抓包分析。

1.1.8 通过网口的 LED 区分网卡

如果机器有很多网口，设置后，对应的网口即会亮灯，即可区分对应关系

ethtool -p eth0

# 参数含义如下:
       -p --identify
              Initiates adapter-specific action intended to enable an operator to easily identify the adapter by sight.  Typically this involves blinking one or more LEDs on the specific network port.
              启动特定于适配器的操作，以使操作员能够轻松地通过视觉识别适配器。这通常涉及闪烁特定网络端口上的一个或多个LED。

           [N]   Length of time to perform phys-id, in seconds.

1.1.9 持久化配置（无需 reboot）

通过 ethtool 设置后，reboot 仍会恢复为设置前的状态。但可通过写配置文件的方式来持久化。

• ubuntu 设置如下：在 /etc/network/interfaces 配置则会持久化。

# vim /etc/network/interfaces
post-up ethtool -s eno1 speed 1000 duplex full autoneg off # 此行应为本文件的最后一行

• SUSE 设置如下：
  modify the /etc/sysconfig/network/ifcfg-eth-id file and include a new script using POST_UP_SCRIPT variable as shown below. Include the below line as the last line in the corresponding eth1 adpater config file.

# vim /etc/sysconfig/network/ifcfg-eth-id
POST_UP_SCRIPT='eth1'

Then, create a new file scripts/eth1 as shown below under /etc/sysconfig/network directory. Make sure that the script has execute permission and ensure that the ethtool utility is present under /sbin directory.

# cd /etc/sysconfig/network/

# vim scripts/eth1
#!/bin/bash
/sbin/ethtool -s duplex full speed 100 autoneg off