Keepalived：Keepalived的作用是检测web服务器的状态，如果有一台web服务器死机，或工作出现故障，Keepalived将检测到，并将有故障的web 服务器从系统中剔除，当web服务器工作正常后Keepalived自动将web服务器加入到服务器群中，这些工作全部自动完成，不需要人工干涉，需要人工做的只是修复故障的web服务器。
LVS：LVS是Linux Virtual Server的简写，意即Linux虚拟服务器，是一个虚拟的服务器集群系统。
实验系统：CentOS 6.6_x86_64
实验前提：提前准备好编译环境，防火墙和selinux都关闭
实验说明：本实验共有4台主机，其中keep1和keep2为2台前端的keepalived服务器，real1和real2为LVS中的realserver，IP地址对应如拓扑图。
实验软件：httpd-2.2.15 keepalived-1.2.19
实验拓扑：
一、配置realserver
1.安装httpd：
yum -y install httpd
2.配置内核参数：
echo 1 > /proc/sys/net/ipv4/conf/lo/arp_ignore //仅在请求的地址配置在请求报文的接口进行响应
echo 1 > /proc/sys/net/ipv4/conf/all/arp_ignore
echo 2 > /proc/sys/net/ipv4/conf/lo/arp_announce //表示仅通告网络直连的接口的地址
echo 2 > /proc/sys/net/ipv4/conf/all/arp_announce
3.增加测试页面并配置VIP：
real1上：
ifconfig lo:0 192.168.19.150 netmask 255.255.255.255 broadcast 192.168.19.150 up //配置VIP
ifconfig lo:1 192.168.19.151 netmask 255.255.255.255 broadcast 192.168.19.151 up
route add -host 192.168.19.150 dev lo:0 //配置路由
route add -host 192.168.19.151 dev lo:1
vim /var/www/html/index.html
---------------------------------------------
<h1>realserver1</h1>
---------------------------------------------
service httpd start
real2上：
ifconfig lo:0 192.168.19.150 netmask 255.255.255.255 broadcast 192.168.19.150 up
ifconfig lo:1 192.168.19.151 netmask 255.255.255.255 broadcast 192.168.19.151 up
route add -host 192.168.19.150 dev lo:0
route add -host 192.168.19.151 dev lo:1
vim /var/www/html/index.html
---------------------------------------------
<h1>realserver2</h1>
---------------------------------------------
service httpd start
二、安装并配置keepalived
1.编译安装keepalived，在keep1和keep2上操作：
wget
tar xf keepalived-1.2.19.tar.gz
cd keepalived-1.2.19
./configure --prefix=/usr/local/keepalived
make && make install
cp -p /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/
chkconfig --add keepalived
chkconfig keepalived on
ln -sv /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/keepalived
cp -p /usr/local/keepalived/sbin/keepalived /usr/sbin/keepalived
ln -sv /usr/local/keepalived/etc/keepalived/ /etc/keepalived
yum -y install ipvsadm //安装LVS工具
复制代码
2.配置keepalived：
keep1上：
vim /etc/keepalived/keepalived.conf
----------------------------------------------------
vrrp_instance VI_1 {
state MASTER
interface eth0
virtual_router_id 31
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass abcd
}
virtual_ipaddress {
192.168.19.150
}
}
vrrp_instance VI_2 {
state BACKUP
interface eth0
virtual_router_id 41
priority 99
advert_int 1
authentication {
auth_type PASS
auth_pass abcd
}
virtual_ipaddress {
192.168.19.151
}
}
virtual_server 192.168.19.150 80 {
delay_loop 6
lb_algo rr //LVS算法
lb_kind DR //调度类型
protocol TCP