linux下如何看网卡是千兆还是百兆的

一、命令详解
ethtool是Linux下用于查询及设置网卡参数的命令。
ethtool [options]
命令选项：

ethtool ethX /
ethtool –h //显示ethtool的命令帮助(help)
ethtool –i ethX //查询ethX网口的相关信息
ethtool –d ethX //查询ethX网口注册性信息
ethtool –r ethX //重置ethX网口到自适应模式
ethtool –S ethX //查询ethX网口收发包统计
ethtool –s ethX [speed 10|100|1000]\ //设置网口速率10/100/1000M
[duplex half|full]\ //设置网口半/全双工
[autoneg on|off]\ //设置网口是否自协商
[port tp|aui|bnc|mii]\ //设置网口类型

二、查看过程
2.1 ifconfig查看网卡信息

[root@master ~]# ifconfig
ens33: flags=4163  mtu 1500
        inet 192.168.64.129  netmask 255.255.255.0  broadcast 192.168.64.255
        inet6 fe80::b00e:da4d:a946:25c4  prefixlen 64  scopeid 0x20
        ether 00:0c:29:49:83:af  txqueuelen 1000  (Ethernet)
        RX packets 53  bytes 5995 (5.8 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 58  bytes 8095 (7.9 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10
        loop  txqueuelen 1  (Local Loopback)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

2.1 ethtool查看网卡带宽

1、[root@master ~]# ethtool ens33
Settings for ens33:
	Supported ports: [ TP ]
	Supported link modes:   10baseT/Half 10baseT/Full 
	                        100baseT/Half 100baseT/Full 
	                        1000baseT/Full 
	Supported pause frame use: No
	Supports auto-negotiation: Yes
	Advertised link modes:  10baseT/Half 10baseT/Full 
	                        100baseT/Half 100baseT/Full 
	                        1000baseT/Full 
	Advertised pause frame use: No
	Advertised auto-negotiation: Yes
	Speed: 1000Mb/s  ------------------------------------>网卡速度 ，可知现在是千兆网卡
	Duplex: Full
	Port: Twisted Pair
	PHYAD: 0
	Transceiver: internal
	Auto-negotiation: on
	MDI-X: off (auto)
	Supports Wake-on: d
	Wake-on: d
	Current message level: 0x00000007 (7)
			       drv probe link
	Link detected: yes

三、ethtool其他命令选项

1）[root@linux /]# ethtool -i eth1
   driver: e1000
   version: 5.0.43-k1
   firmware-version: N/A
   bus-info: 06:08.1
2）[root@linux /]# ethtool -S eth1
   NIC statistics:
     rx_packets: 58068300
     tx_packets: 87124083
     rx_bytes: 1589713008
     tx_bytes: 2165825901
     rx_errors: 0
     tx_errors: 0
     rx_dropped: 0
     tx_dropped: 0
     multicast: 0
     collisions: 0
     rx_length_errors: 0
     rx_over_errors: 0
     rx_crc_errors: 0
     rx_frame_errors: 0
     rx_fifo_errors: 0
     rx_missed_errors: 0
     tx_aborted_errors: 0
     tx_carrier_errors: 0
     tx_fifo_errors: 0
     tx_heartbeat_errors: 0
     tx_window_errors: 0
3）[root@linux /]# ethtool -s eth1 autoneg off speed 100 duplex full


相关：
1）[root@linux /]# which ethtool
    /sbin/ethtool
2）[root@linux /]# rpm -qf /sbin/ethtool
   ethtool-1.6-5
3）怎样使ethtool设置永久保存在网络设备中？
   解决方法一:
    ethtool设置可通过/etc/sysconfig/network-scripts/ifcfg-ethX文件保存,从而在设备下次启动时激活选项。 
例如：ethtool -s eth0 speed 100 duplex full autoneg off
此指令将eth0设备设置为全双工自适应，速度为100Mbs。若要eth0启动时设置这些参数, 修改文件/etc/sysconfig/network-scripts/ifcfg-eth0 ，添加如下一行: 
 ETHTOOL_OPTS="speed 100 duplex full autoneg off"
解决方法二:
将ethtool设置写入/etc/rc.d/rc.local之中。

参考：https://blog.csdn.net/wh8_2011/article/details/50442296