一次网络问题排查

bash 复制代码

[root@kylin10 ~1# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    valid_Ift forever preferred_lft forever
    inet6 ::1/128 scope host
    valid_lft forever preferred_lft forever
2: em1: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 gdisc mq state DOWN group default qlen 1000
    link/ether 04:7b:cb:4d:ab:d7 brd ff:ff:ff:ff:ff:ff
3: em2: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc nq state DOWN group default qlen 1000
    link/ether 04:7b:cb:4d:ab:d8 brd ff:ff:ff:ff:ff:ff
[root@kylin10 ~1#

这里，我们看到em1、em2都出现了标记NO-CARRIER，这说明，两块网口都没有网络通路，也可以理解为没有插网线。

bash 复制代码

[root@kylin10 ~1# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default glen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    valid_Ift forever preferred_lft_ forever
    inet6 ::1/128 scope host
    valid_lft forever preferred_lft forever
2: em1: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN group default qlen 1000
    link/ether 04:7b:cb:4d:ab:d7 brd ff:ff:ff:ff:ff:ff
3: em2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 04:7b:cb:4d:ab:d8 brd ff:ff:ff:ff:ff:ff
    inet6 fe80::69f2:c2fd:b4bf:ff74/64 scope link noprefixroute
    valid_lft forever preferred_lft forever
[root@kylin10 ~]#

这里，我们看到em2都没有了NO-CARRIER标记，这说明，该网口已经插上了网线，网路是通的。

bash 复制代码

[root@kylin10 ~1# nmcli connection show
NAME    UUID                                   TYPE        DEVICE
em2     ca68973a-5653-4c6f-9099-71824172a13b    ethernet    --
[root@kylin10 ~1#

像这种情况，说明连接没有与网口绑定，可以删除重新创建，也可以直接修改。

删除的话，可以用下面命令删除

bash 复制代码

[root@kylin10 ~1# nmcli connection delete em2
[root@kylin10 ~1#

删除以后，我们就看不到相应的连接了，如下所示:

bash 复制代码

[root@kylin10 ~1# nmcli connection show
NAME    UUID                                   TYPE        DEVICE
[root@kylin10 ~1#

bash 复制代码

nmcli con add \
    type ethernet \
    con-name em1 \
    ifname em1 \
    ipv4 192.168.43.207/24 \
    gw4 192.168.43.1 \
    dns4 223.6.6.6