A network card in Linux contains multiple IPs, and the method of upgrading from IP to primary IP

Today, when viewing a virtual machine, you find that a network card contains multiple IP addresses:

eno16777736: <BROADCAST,MULTICAST,UP,LOWER_UP> MTU theQdisc Pfifo_fast State up Qlen +Link/etherxx: 0c: in: 6b:a5:a2 BRD ff:ff:ff:ff:ff:ff inet192.168.213.132/ -Brd192.168.213.255Scope Global Dynamic eno16777736 valid_lft 1726sec preferred_lft 1726sec inet192.168.213.34/ -Brd192.168.213.255Scope Global Secondary eno16777736 valid_lft forever Preferred_lft Forever

Where 192.168.213.132 is the primary IP address, 192.168.213.34 to remove the master IP address from the IP address, execute the following command:

192.168. 213.132 Dev eno16777736

Viewing the results will reveal that the IP address is not there.

It turns out that there is a kernel parameter that controls this:

When you drop the primary IP of a subnet, all related IP will be down.
Set a kernel parameter that can be promoted from IP to primary IP when the primary IP is down:

Echo " 1 " >/proc/sys/net/ipv4/conf/all/promote_secondaries

Execute the command to remove the IP again:

192.168. 213.132 Dev eno16777736

Enter IP addr To view the results:

 the  +     link: 0c:6b:a5:a2 brd    ff:ff:ff:ff:ff:ff192.168  . 213.34/192.168. 213.255 Scope Global eno16777736      valid_lft forever Preferred_lft Forever

Upgrade from IP to primary IP, done!

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A network card in Linux contains multiple IPs, and the method of upgrading from IP to primary IP