因为公网线路需要更换IP地址，在过渡期间可以二个IP地址同时使用，为此需要为单个网卡绑定二个IP地址。
(1)增加新IP地址。为了以后删除旧IP地址方便，直接将eth1的IP改为新IP，并重新将eth1:1接口为旧IP地址。
[root@web network-scripts]# pwd
/etc/sysconfig/network-scripts
[root@web network-scripts]# cp ifcfg-eth1 ifcfg-eth1:1
[root@web network-scripts]# vi ifcfg-eth1:1
DEVICE=eth1:1
###GATEWAY=211.151.92.17
[root@web network-scripts]# vi ifcfg-eth1
IPADDR=121.52.160.29
GATEWAY=121.52.160.17
(2)重新启动网络，并查看新网络配置
[root@web network-scripts]# /etc/init.d/network restart
[root@web network-scripts]# ifconfig eth1
eth1 Link encap:Ethernet HWaddr 00:1E:4F:37:40:6F
inet addr:121.52.160.29 Bcast:121.52.160.31 Mask:255.255.255.240
inet6 addr: fe80::21e:4fff:fe37:406f/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:11468 errors:0 dropped:0 overruns:0 frame:0
TX packets:17259 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1037939 (1013.6 KiB) TX bytes:19258257 (18.3 MiB)
Interrupt:16 Memory:f4000000-f4012100
[root@web network-scripts]# ifconfig eth1:1
eth1:1 Link encap:Ethernet HWaddr 00:1E:4F:37:40:6F
inet addr:211.151.92.29 Bcast:211.151.92.31 Mask:255.255.255.240
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
Interrupt:16 Memory:f4000000-f4012100
[root@web network-scripts]# netstat -nr
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
211.151.92.16 0.0.0.0 255.255.255.240 U 0 0 0 eth1
121.52.160.16 0.0.0.0 255.255.255.240 U 0 0 0 eth1
166.111.120.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
192.168.122.0 0.0.0.0 255.255.255.0 U 0 0 0 virbr0
166.111.0.0 166.111.120.1 255.255.0.0 UG 0 0 0 eth0
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth1
0.0.0.0 121.52.160.17 0.0.0.0 UG 0 0 0 eth1
(3)修改策略路由脚本。
/sbin/ip route add 0/0 via 121.52.160.17 table 120
/sbin/ip rule add from 121.52.160.29 table 120 pref 100
