一、bond的工作原理
所谓的bond就是将两块或两块以上网卡绑定同一个IP地址对外提供服务，从而实现负载均衡高可用。当然，直接给两块网卡设置同一IP地址 是不可能的。通过bonding，虚拟一块网卡对外提供连接， 物理网卡的被修改为相同的MAC地址。
二、bond工作模式分类
1）Mode 0 (balance-rr) 轮转（Round-robin）策略：从头到尾顺序的在每一个slave 接口上面发送数据包。本模式提供负载均衡和容错的能力
2）Mode 1 (active-backup) 活动-备份（主备）策略：在绑定中，只有一个slave被激活。 当且仅当活动的slave接口失败时才会激活其他slave。为了 避免交换机发生混乱此时绑定的MAC地址只有一个外部端口上可见
3）Mode 3 (broadcast) 广播策略：在所有的slave接口上传送所有的报文。本模式提供 无容错能力。
三、实现步骤
1、为每个设备生成独立的接口配置文件，关闭NetworkManager服务。
chkconfig --level 3 NetworkManager off
2、添加网卡，配置静态联网(bond0)
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[root@centos6 network-scripts]
# cat ifcfg-bond0
DEVICE=bond0
IPADDR=10.1.249.34
PRFIX=16
GATEWAY=10.1.249.254
DNS1=8.8.8.8
BONDING_OPTS=
"miimon=101 mode=0"
#如果mode=0则为轮转模式，为1则为主备模式，为3则为广播策略
[root@centos6 network-scripts]
# cat ifcfg-eth0
DEVICE=eth0
SLAVE=
yes
MASTER=bond0
[root@centos6 network-scripts]
# cat ifcfg-eth1
DEVICE=eth1
SLAVE=
yes
MASTER=bond0
[root@centos6 network-scripts]
#
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3、随意断开一网卡测试，并查看结果
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[root@centos6 network-scripts]
# !cat
cat
/proc/net/bonding/bond0
Ethernet Channel Bonding Driver: v3.7.1 (April 27, 2011)
Bonding Mode: fault-tolerance (active-backup)
Primary Slave: None
Currently Active Slave: eth0
MII Status: up
MII Polling Interval (ms): 102
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:29:7c:55:8d
Slave queue ID: 0
Slave Interface: eth1
MII Status: up
Speed: 1000 Mbps
Duplex: full
Link Failure Count: 0
Permanent HW addr: 00:0c:29:7c:55:97
Slave queue ID: 0
[root@centos6 network-scripts]
#
[root@centos6 ~]
# cat /proc/net/bonding/bond0
Ethernet Channel Bonding Driver: v3.7.1 (April 27, 2011)
Bonding Mode: load balancing (round-robin)
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: 3
Permanent HW addr: 00:0c:29:7c:55:8d
Slave queue ID: 0
Slave Interface: eth1
MII Status: down
Speed: Unknown
Duplex: Unknown
Link Failure Count: 3
Permanent HW addr: 00:0c:29:7c:55:97
Slave queue ID: 0
[root@centos6 ~]
# cat /proc/net/bonding/bond0
Ethernet Channel Bonding Driver: v3.7.1 (April 27, 2011)
Bonding Mode: fault-tolerance (broadcast)
MII Status: up
MII Polling Interval (ms): 101
Up Delay (ms): 0
Down Delay (ms): 0
Slave Interface: eth0
MII Status: up
Speed: 1000 Mbps
Duplex: full
Link Failure Count: 2
Permanent HW addr: 00:0c:29:7c:55:8d
Slave queue ID: 0
Slave Interface: eth1
MII Status: up
Speed: 1000 Mbps
Duplex: full
Link Failure Count: 1
Permanent HW addr: 00:0c:29:7c:55:97
Slave queue ID: 0
[root@centos6 ~]
#
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[root@centos6 network-scripts]
# ifconfig
bond0 Link encap:Ethernet HWaddr 00:0C:29:7C:55:8D
#三的MAC地址信息是一样的，代表绑定为一块网卡
inet addr:10.1.249.34 Bcast:10.255.255.255 Mask:255.0.0.0
inet6 addr: fe80::20c:29ff:fe7c:558d
/64
Scope:Link
UP BROADCAST RUNNING MASTER MULTICAST MTU:1500 Metric:1
RX packets:62258 errors:0 dropped:0 overruns:0 frame:0
TX packets:7493 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:5599522 (5.3 MiB) TX bytes:716163 (699.3 KiB)
eth0 Link encap:Ethernet HWaddr 00:0C:29:7C:55:8D
#三的MAC地址信息是一样的，代表绑定为一块网卡
UP BROADCAST RUNNING SLAVE MULTICAST MTU:1500 Metric:1
RX packets:32698 errors:0 dropped:0 overruns:0 frame:0
TX packets:4300 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:2915521 (2.7 MiB) TX bytes:393343 (384.1 KiB)
eth1 Link encap:Ethernet HWaddr 00:0C:29:7C:55:8D
#三的MAC地址信息是一样的，代表绑定为一块网卡
UP BROADCAST RUNNING SLAVE MULTICAST MTU:1500 Metric:1
RX packets:33832 errors:0 dropped:0 overruns:0 frame:0
TX packets:3359 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:3059478 (2.9 MiB) TX bytes:339826 (331.8 KiB)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1
/128
Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:425 errors:0 dropped:0 overruns:0 frame:0
TX packets:425 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:42694 (41.6 KiB) TX bytes:42694 (41.6 KiB)
[root@centos6 network-scripts]
#
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截图演示：
1、关闭NetworkManager服务
2、准备所有配置文件
3、重启网络服务
4、断开一网卡在物理机上ping本ip地址，测试主备功能
结论：
同理可使用不同的bond工作模式进行测试，结果为，当处于mode0时为轮转模式有容错能力可坏一块网卡，当处于mode1时为主备模式有容错能力可坏一块网卡，当处于mode3时为广播策略模式，亲测，只要工作的网卡不坏则正常工作，当开始不是工作的网卡切换为工作网卡时则不能工作。
本文转自chengong1013 51CTO博客，原文链接：http://blog.51cto.com/purify/1845804，如需转载请自行联系原作者
