Linux双网卡绑定是通过Bonding技术实现使用两块网卡虚拟成为一块网卡设备，两块网卡使用共同的IP地址，可实现负载均衡，网卡冗余。bonding的实现前提是使用相同型号的网卡芯片。

以下练习在VM的虚拟环境使用redhat5.4并添加双网卡

1.redhat5.X默认已支持bonding，可通过以下命令查看： 
[root@server1 ~]# modinfo bonding 
filename:       /lib/modules/2.6.18-164.el5/kernel/drivers/net/bonding/bonding.k        o 
author:         Thomas Davis, tadavis@lbl.gov and many others 
description:    Ethernet Channel Bonding Driver, v3.4.0 
version:        3.4.0 
license:        GPL 
srcversion:     3D3684A1DE11F2E8B0D4E80 
depends:        ipv6 
vermagic:       2.6.18-164.el5 SMP mod_unload 686 REGPARM 4KSTACKS gcc-4.1 
parm:           max_bonds:Max number of bonded devices (int) 
parm:           num_grat_arp:Number of gratuitous ARP packets to send on failove        r event (int) 
parm:           num_unsol_na:Number of unsolicited IPv6 Neighbor Advertisements         packets to send on failover event (int) 
parm:           miimon:Link check interval in milliseconds (int) 
parm:           updelay:Delay before considering link up, in milliseconds (int) 
parm:           downdelay:Delay before considering link down, in milliseconds (         nt) 
parm:           use_carrier:Use netif_carrier_ok (vs MII ioctls) in miimon; 0 f         r off, 1 for on (default) (int) 
parm:           mode:Mode of operation : 0 for balance-rr, 1 for active-backup,         2 for balance-xor, 3 for broadcast, 4 for 802.3ad, 5 for balance-tlb, 6 for bal         nce-alb (charp) 
parm:           primary:Primary network device to use (charp) 
parm:           lacp_rate:LACPDU tx rate to request from 802.3ad partner (slow/         ast) (charp) 
parm:           xmit_hash_policy:XOR hashing method: 0 for layer 2 (default), 1         for layer 3+4 (charp) 
parm:           arp_interval:arp interval in milliseconds (int) 
parm:           arp_ip_target:arp targets in n.n.n.n form (array of charp) 
parm:           arp_validate:validate src/dst of ARP probes: none (default), ac         ive, backup or all (charp) 
parm:           fail_over_mac:For active-backup, do not set all slaves to the s         me MAC.  none (default), active or follow (charp) 
module_sig:     883f3504a8b7aed18758d6145e112aa1909f62632a4a9b30e790b7b31a74bde         31a772fa4909f40969e891a448344afce6ded18dd8e6ddf11a4

2.建立虚拟的网卡接口，配置网卡接口信息等信息

[root@server1 ~]# cd /etc/sysconfig/network-scripts/ 
[root@server1 network-scripts]# cp ifcfg-lo ifcfg-bond0 
[root@server1 network-scripts]# vim ifcfg-bond0 
DEVICE=bond0 
IPADDR=192.168.0.254 
NETMASK=255.255.255.0 
NETWORK=192.168.0.0 
BROADCAST=192.168.0.255 
ONBOOT=yes 
BOOTPROTO=none 
USERCTL=no 
BONDING_OPTS="mode=0 miimon=100"

BONDING_OPTS选项中的mode=0指的是使用指负载均衡模式,如果这个参数为1，表示冗余功能。miimon=100表示系统每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。

[root@server1 network-scripts]# vim ifcfg-eth0 
DEVICE=eth0 
BOOTPROTO=none 
ONBOOT=yes 
MASTER=bond0 
SLAVE=yes

[root@server1 network-scripts]# vim ifcfg-eth1 
DEVICE=eth1 
BOOTPROTO=none 
ONBOOT=yes 
MASTER=bond0 
SLAVE=yes

3.修改配置使系统启动时加载bonding模块使用bond0接口。在末尾添加一行： 
[root@server1 ~]# vim /etc/modprobe.conf 
alias eth0 vmxnet 
alias scsi_hostadapter mptbase 
alias scsi_hostadapter1 mptspi 
alias scsi_hostadapter2 ata_piix 
# Added by VMware Tools 
install pciehp /sbin/modprobe -q --ignore-install acpiphp; /bin/true 
install pcnet32 (/sbin/modprobe -q --ignore-install vmxnet || /sbin/modprobe -q --ignore-install pcnet32 $CMDLINE_OPTS);/bin/true 
alias eth1 vmxnet 
alias bond0 bonding

4.重启网络服务，查看绑定情况：

[root@server1 ~]# /etc/init.d/network restart

[root@server1 ~]# ifconfig 
bond0     Link encap:Ethernet  HWaddr 00:0C:29:41:E1:48 
          inet addr:192.168.0.254  Bcast:192.168.0.255  Mask:255.255.255.0 
          inet6 addr: fe80::20c:29ff:fe41:e148/64 Scope:Link 
          UP BROADCAST RUNNING MASTER MULTICAST  MTU:1500  Metric:1 
          RX packets:2913 errors:0 dropped:0 overruns:0 frame:0 
          TX packets:2338 errors:0 dropped:0 overruns:0 carrier:0 
          collisions:0 txqueuelen:0 
          RX bytes:274948 (268.5 KiB)  TX bytes:357004 (348.6 KiB)

eth0      Link encap:Ethernet  HWaddr 00:0C:29:41:E1:48 
          UP BROADCAST RUNNING SLAVE MULTICAST  MTU:1500  Metric:1 
          RX packets:2289 errors:0 dropped:0 overruns:0 frame:0 
          TX packets:2176 errors:0 dropped:0 overruns:0 carrier:0 
          collisions:0 txqueuelen:1000 
          RX bytes:209531 (204.6 KiB)  TX bytes:326498 (318.8 KiB) 
          Interrupt:59 Base address:0x2024

eth1      Link encap:Ethernet  HWaddr 00:0C:29:41:E1:48 
          UP BROADCAST RUNNING SLAVE MULTICAST  MTU:1500  Metric:1 
          RX packets:629 errors:0 dropped:0 overruns:0 frame:0 
          TX packets:175 errors:0 dropped:0 overruns:0 carrier:0 
          collisions:0 txqueuelen:1000 
          RX bytes:65717 (64.1 KiB)  TX bytes:32508 (31.7 KiB) 
          Interrupt:51 Base address:0x20a4

[root@server1 ~]# cat /proc/net/bonding/bond0 
Ethernet Channel Bonding Driver: v3.4.0 (October 7, 2008)

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 
Link Failure Count: 1 
Permanent HW addr: 00:0c:29:41:e1:48

Slave Interface: eth1 
MII Status: up 
Link Failure Count: 1 
Permanent HW addr: 00:0c:29:41:e1:52

通过使用bonding技术实现的网卡负载均衡模式就完成了。