https://www.linuxidc.com/Linux/2015-11/125369.htm

Linux bonding 主备模式slave网卡切换的方法

我们有时候做演练或测试，测试bonding

slave网卡切换，或者疑是因为一块网卡有问题，想切换到另外一块slave网卡，通常情况下，我们可能采用ifdown eth0或ifconfig

eth0 down的方法来切换到另外一块网卡，但是这种方法在 生产环境中可能出现网络及系统告警或者可能丢包，也可能也存在一些风险。

下面介绍一种方法，不需要ifdown网卡就能切换，比较适合于在生产环境中正在提供业务的linux服务器，比如出现了丢包，或者有闪断、网络慢或者日志有网络报错，怀疑是此网卡硬件或固件有问题，想切换到另外一块slave网卡，而又不想断网出现监控系统告警，业务中断等对业务高可用要求比较高的情况。

# ifenslave -c bond0 eth1 将一个物理接口eth1作为active接口

不建议# ifenslave -d bond0 eth0    //从bond0中删除掉eth0

如下所示(适用于主备模式)

[root@RedHat ~]# cat /proc/net/bonding/bond0

Ethernet Channel Bonding Driver: v3.6.0 (September 26, 2009)

Bonding Mode: fault-tolerance (active-backup) (fail_over_mac active)

Primary Slave: None

Currently Active Slave: eth0

MII Status: up

MII Polling Interval (ms): 100

Up Delay (ms): 0

Down Delay (ms): 0

Slave Interface: eth0

MII Status: up

Speed: 1000 Mbps

Duplex: full

Link Failure Count: 0

Permanent HW addr: 00:0c:29:5a:9d:28

Slave queue ID: 0

Slave Interface: eth1

MII Status: up

Speed: 1000 Mbps

Duplex: full

Link Failure Count: 0

Permanent HW addr: 00:0c:29:5a:9d:32

Slave queue ID: 0

[root@redhat ~]# ifenslave -c bond0 eth1

[root@redhat ~]# cat /proc/net/bonding/bond0

Ethernet Channel Bonding Driver: v3.6.0 (September 26, 2009)

Bonding Mode: fault-tolerance (active-backup) (fail_over_mac active)

Primary Slave: None

Currently Active Slave: eth1

MII Status: up

MII Polling Interval (ms): 100

Up Delay (ms): 0

Down Delay (ms): 0

Slave Interface: eth0

MII Status: up

Speed: 1000 Mbps

Duplex: full

Link Failure Count: 0

Permanent HW addr: 00:0c:29:5a:9d:28

Slave queue ID: 0

Slave Interface: eth1

MII Status: up

Speed: 1000 Mbps

Duplex: full

Link Failure Count: 0

Permanent HW addr: 00:0c:29:5a:9d:32

Slave queue ID: 0

[root@redhat ~]#

整个过程没有出现丢包，断网