Linux双网卡绑定实现

Linux双网卡绑定实现就是使用两块网卡虚拟成为一块网卡，这个聚合起来的设备看起来是一个单独的以太网接口设备，通俗点讲就是两块网卡具有相同的IP地址而并行链接聚合成一个逻辑链路工作。

   在正常情况下，网卡只接收目的硬件地址(MAC Address)是自身Mac的以太网帧，对于别的数据帧都滤掉，以减轻驱动程序的负担。但是网卡也支持另外一种被称为混杂promisc的模式，可以接收网络上所有的帧，比如说tcpdump，就是运行在这个模式下。

bonding也运行在这个模式下，而且修改了驱动程序中的mac地址，将两块网卡的Mac地址改成相同，可以接收特定mac的数据帧。然后把相应的数据帧传送给bond驱动程序处理。

测试环境版本：

CentOS release 5.3 (Final) X86_64

2.6.18-128.el5

具体的配置步骤如下：

1 新建/etc/sysconfig/network-scripts/ifcfg-bond0

[root@rac4 network-scripts]# cat ifcfg-bond0      

# Intel Corporation 82545EM Gigabit Ethernet Controller (Copper)

DEVICE=bond0

BOOTPROTO=static

IPADDR=10.250.7.220

NETMASK=255.255.255.0

BROADCAST=10.250.7.255

ONBOOT=yes

TYPE=Ethernet

GATEWAY=10.250.7.254

USERCTL=no

2更改需要bond的网卡的属性：

[root@rac4 network-scripts]# cat ifcfg-eth0       

# Intel Corporation 82545EM Gigabit Ethernet Controller (Copper)

DEVICE=eth0

BOOTPROTO=none

ONBOOT=yes

USERCTL=no

MASTER=bond0

SLAVE=yes

[root@rac4 network-scripts]# cat ifcfg-eth1

# Intel Corporation 82545EM Gigabit Ethernet Controller (Copper)

DEVICE=eth1

BOOTPROTO=none

ONBOOT=yes

USERCTL=no

MASTER=bond0

SLAVE=yes

3 编辑/etc/modprobe.conf文件,加入以下红色标记的内容     

[root@rac4 network-scripts]# vi /etc/modprobe.conf

alias scsi_hostadapter mptbase

alias scsi_hostadapter1 mptspi

alias scsi_hostadapter2 ata_piix

alias eth0 e1000

alias eth1 e1000

alias bond0 bonding

options bond0 miimon=100 mode=1

说明：

miimon是用来进行链路监测的，比如:miimon=100，那么系统每100ms监测一次链路连接状态，如果有一条线路不通就转入另一条线路；mode的值表示工作模式，他共有0，1,2,3四种模式，常用的为0,1两种。 

mode=0表示load balancing  (round-robin)为负载均衡方式，两块网卡都工作。 

mode=1表示fault-tolerance (active-backup)提供冗余功能，工作方式是主备的工作方式,也就是说默认情况下只有一块网卡工作,另一块做备份.

4 加入/etc/rc.d/rc.local启动项红色标记内容 

[root@rac4 network-scripts]# vi /etc/rc.d/rc.local 

#!/bin/sh

# This script. will be executed *after* all the other init scripts.

# You can put your own initialization stuff in here if you don't

# want to do the full Sys V style. init stuff.

touch /var/lock/subsys/local

ifenslave bond0 eth0 eth1

5 启动bond0

[root@rac4 network-scripts]#ifconfig  bond0 10.250.7.220 up

当使用ifenslave 启动的时候报出如下错误：启动bond0的时候已经将eth0 eth1添加到/sys/class/net/bond0/bonding/slaves 里面了

[root@rac4 network-scripts]# ifenslave  bond0 eth0 eth1

Illegal operation: The specified slave interface 'eth0' is already a slave

Master 'bond0', Slave 'eth0': Error: Enslave failed

Illegal operation: The specified slave interface 'eth1' is already a slave

Master 'bond0', Slave 'eth1': Error: Enslave failed

[root@rac4 network-scripts]# ifenslave  bond0  eth1    

Illegal operation: The specified slave interface 'eth1' is already a slave

Master 'bond0', Slave 'eth1': Error: Enslave failed

最后重启服务器：

[root@rac4 ~]# reboot

下面讨论一下绑定网卡的特性：

当bonding 属性 mode=1时,绑定网卡工作在主备模式下,这时eth1作为备份网卡是no arp的 

验证网卡的配置信息：

[root@rac4 ~]# ifconfig                                

bond0     Link encap:Ethernet  HWaddr 00:50:56:8F:22:48  

          inet addr:10.250.7.220  Bcast:10.250.7.255  Mask:255.255.255.0

          inet6 addr: fe80::250:56ff:fe8f:2248/64 Scope:Link

          UP BROADCAST RUNNING MASTER MULTICAST  MTU:1500  Metric:1

          RX packets:1109 errors:0 dropped:0 overruns:0 frame.:0

          TX packets:120 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:0 

          RX bytes:84101 (82.1 KiB)  TX bytes:13835 (13.5 KiB)

eth0      Link encap:Ethernet  HWaddr 00:50:56:8F:22:48  

          UP BROADCAST RUNNING SLAVE MULTICAST  MTU:1500  Metric:1

          RX packets:566 errors:0 dropped:0 overruns:0 frame.:0

          TX packets:60 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000 

          RX bytes:43053 (42.0 KiB)  TX bytes:5791 (5.6 KiB)

          Base address:0x2000 Memory:d8920000-d8940000 

eth1      Link encap:Ethernet  HWaddr 00:50:56:8F:22:48  

          UP BROADCAST RUNNING SLAVE MULTICAST  MTU:1500  Metric:1

          RX packets:543 errors:0 dropped:0 overruns:0 frame.:0

          TX packets:61 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000 

          RX bytes:41048 (40.0 KiB)  TX bytes:8214 (8.0 KiB)

          Base address:0x2040 Memory:d8940000-d8960000 

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:16436  Metric:1

          RX packets:5694 errors:0 dropped:0 overruns:0 frame.:0

          TX packets:5694 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:0 

          RX bytes:8581664 (8.1 MiB)  TX bytes:8581664 (8.1 MiB)

[root@rac4 ~]#cat /proc/net/bonding/bond0 

Ethernet Channel Bonding Driver: v3.2.4 (January 28, 2008)

Bonding Mode:fault-tolerance (active-backup)主备模式

Primary Slave: None

Currently Active Slave: eth0 当前工作网卡为eth0

MII Status: up

MII Polling Interval (ms): 100

Up Delay (ms): 0

Down Delay (ms): 0

Slave Interface: eth0

MII Status: up

Link Failure Count: 0

Permanent HW addr: 00:50:56:8f:22:48

Slave Interface: eth1

MII Status: up

Link Failure Count: 0

Permanent HW addr: 00:50:56:8f:7d:6

mode=1时，当一个网络接口失效时(例如主交换机掉电等),不回出现网络中断,系统会按照cat /etc/rc.d/rc.local里指定网卡的顺序工作,机器仍能对外服务,起到了失效保护的功能.

对于mode=0 负载均衡工作模式,此模式能提供两倍的带宽,在这种情况下出现一块网卡失效,仅仅会是服务器出口带宽下降,也不会影响网络使用。通过查看bond0的工作状态查询能详细的掌握bonding的工作状态：

[root@rac4 ~]#cat /proc/net/bonding/bond0 

Ethernet Channel Bonding Driver: v3.2.4 (January 28, 2008)

Bonding Mode: load balancing (round-robin)--负载模式

MII Status: up

MII Polling Interval (ms): 100

Up Delay (ms): 0

Down Delay (ms): 0

Slave Interface: eth0

MII Status: up

Link Failure Count: 0

Permanent HW addr: 00:50:56:8f:22:48

Slave Interface: eth1

MII Status: up

Link Failure Count: 0

Permanent HW addr: 00:50:56:8f:7d:6f

[root@rac4 ~]# ifconfig

bond0     Link encap:Ethernet  HWaddr 00:50:56:8F:22:48  

          inet addr:10.250.7.220  Bcast:10.250.7.255  Mask:255.255.255.0

          inet6 addr: fe80::250:56ff:fe8f:2248/64 Scope:Link

          UP BROADCAST RUNNING MASTER MULTICAST  MTU:1500  Metric:1

          RX packets:376 errors:0 dropped:0 overruns:0 frame.:0

          TX packets:121 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:0 

          RX bytes:29934 (29.2 KiB)  TX bytes:13014 (12.7 KiB)

eth0      Link encap:Ethernet  HWaddr 00:50:56:8F:22:48  

          UP BROADCAST RUNNING SLAVE MULTICAST  MTU:1500  Metric:1

          RX packets:203 errors:0 dropped:0 overruns:0 frame.:0

          TX packets:61 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000 

          RX bytes:15858 (15.4 KiB)  TX bytes:8146 (7.9 KiB)

          Base address:0x2000 Memory:d8920000-d8940000 

eth1      Link encap:Ethernet  HWaddr 00:50:56:8F:22:48  

          UP BROADCAST RUNNING SLAVE MULTICAST  MTU:1500  Metric:1

          RX packets:173 errors:0 dropped:0 overruns:0 frame.:0

          TX packets:60 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000 

          RX bytes:14076 (13.7 KiB)  TX bytes:4868 (4.7 KiB)

          Base address:0x2040 Memory:d8940000-d8960000 

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:16436  Metric:1

          RX packets:3080 errors:0 dropped:0 overruns:0 frame.:0

          TX packets:3080 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:0 

          RX bytes:4806596 (4.5 MiB)  TX bytes:4806596 (4.5 MiB)