在Linux Router Backup上安裝keepalived的方法是相同的，不同的是配置文件/usr/local/keepalived/etc/keepalived/keepalived.conf，如下：
vrrp_instance VI_1 {
state BACKUP
interface eth1
virtual_router_id 51
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.3.3
}
}
在啟動(dòng)Master上的keepalived之前，我們先看一下Master上eth1的情況：
# ip add show eth1
8: eth1: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 1000
link/ether 00:e0:4c:3a:d7:25 brd ff:ff:ff:ff:ff:ff
inet 192.168.3.1/24 brd 192.168.3.255 scope global eth1
inet6 fe80::2e0:4cff:fe3a:d725/64 scope link
我們看到只有一個(gè)IP地址：192.168.3.1/24，現(xiàn)在我們啟動(dòng)Master上的keepalived：
#/usr/local/keepalived/sbin/keepalived –D –
f /usr/local/keepalived/etc/keepalived/keepalived.conf
現(xiàn)在我們?cè)倏匆幌翸aster上eth1的情況：
# ip add show eth1
8: eth1: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 1000
link/ether 00:e0:4c:3a:d7:25 brd ff:ff:ff:ff:ff:ff
inet 192.168.3.1/24 brd 192.168.3.255 scope global eth1
inet 192.168.3.3/32 scope global eth1
inet6 fe80::2e0:4cff:fe3a:d725/64 scope link
我們看到有兩個(gè)IP地址，其中一個(gè)就是V-Gate:192.168.3.3/32
用同樣的方法啟動(dòng)Backup上的keepalived：
#/usr/local/keepalived/sbin/keepalived –D –
f /usr/local/keepalived/etc/keepalived/keepalived.conf
這樣，當(dāng)Master失效時(shí)，Backup就會(huì)通過(guò)MultiCast地址：224.0.0.18這個(gè)組播地址，獲得這個(gè)消息，并將192.168.3.3這個(gè)地址接管過(guò)來(lái)。
總結(jié)，請(qǐng)你注意一下我們這個(gè)實(shí)驗(yàn)的題目“利用Keepalived的VRRP功能實(shí)現(xiàn)簡(jiǎn)單的路由器備份”，而不是路由備份。我們這個(gè)實(shí)驗(yàn)的目的，是讓大家熟悉VRRP協(xié)議和如何利用Keepalived實(shí)現(xiàn)VRRP協(xié)議。
