CENTOS5下采用LVS +KEEPALIVED实现负载均衡
一、环境OS: CENTOS5.3
VIP:192.168.0.181（外网访问IP地址）
LVS_SRV: 192.168.0.180 （LVS主服务器）
R1：192.168.0.185
R2：192.168.0.186
二、LVS安装
1.软件安装（安装至LVS_SRV）
yum install ipvsadm modcluster system-confi-cluster
也可以选择手工下载源码编译安装，这里不再叙述。
2.配置(lvs.sh)
1) lvs_srv配置
#开启IP转发，仅当DR模式下
echo "1" >/proc/sys/net/ipv4/ip_forward
2) Rn配置(rs.sh)
#!/bin/sh
# ghb in 20120212
# description: Config realserver tunl port and apply arp patch
VIP=192.168.0.181
. /etc/rc.d/init.d/functions
case $1 in
start)
echo "Tunl port starting"
ifconfig lo:0 $VIP netmask 255.255.255.255 broadcast $VIP up
/sbin/route add -host $VIP dev lo:0
echo "1" > /proc/sys/net/ipv4/conf/tunl0/arp_ignore
echo "2" > /proc/sys/net/ipv4/conf/tunl0/arp_announce
echo "1" > /proc/sys/net/ipv4/conf/all/arp_ignore
echo "2" > /proc/sys/net/ipv4/conf/all/arp_announce
sysctl -p
;;
stop)
echo "Tunl port closing"
ifconfig lo:0 down
echo "1" > /proc/sys/net/ipv4/ip_forward
echo "0" > /proc/sys/net/ipv4/conf/all/arp_announce
;;
*)
echo "Usage: $0 {start|stop}"
exit 1
esac
3) Rn配置
Rn下运行
Rs.sh start
三、KEEPALIVED
这里是用keepalived来进行lvs的建立和服务器和vip的健康检查,其实keepalived就像一个shell，他自动的给你做lvs+vrrp。
keepalived本身来做真实服务器的健康检查，vrrp来做vip的冗余。
1.软件安装
# tar -zxvf keepalived-1.1.15.tar.gz
# cd keepalived-1.1.15
# ./configure –-enable-lvs-syncd –-enable-lvs –-with-kernel-dir= /usr/src/kernels/2.6.18-128.e15-i686
#（注意：–-with-kernel-dir参数必需加载，否则无法支持KEEPALIVED调用IPVS完成LVS应用，内核版本根据实际机器情况填写，当然，不要告诉我你安装系统的时候没有选择安装系统开发包工具）
# make && make install
cp /usr/local/etc/rc.d/init.d/keepalived/etc/init.d/
cp /usr/local/etc/sysconfig/keepalived/etc/sysconfig/
mkdir /etc/keepalived
cp /usr/local/etc/keepalived/keepalived.conf/etc/keepalived/
cp /usr/local/sbin/keepalived/usr/sbin/
2.网卡设置lvs-init.sh
#!/bin/sh
VIP=192.168.0.181
# set the Virtual IP Address
/sbin/ifconfig eth0:0 $VIP broadcast $VIP netmask 255.255.255.255 up
/sbin/route add -host $VIP dev eth0:0
#开启IP转发，仅当DR模式下
echo "1" >/proc/sys/net/ipv4/ip_forward
或者
Cp /etc/sysconfig/network-scripts/ifcfg-eth0 /etc/sysconfig/network-script/ifcfg-eth0:0
修改内容：
DEVICE=eth0:0
BOOTPROTO=static
IPADDR=192.168.0.181
NETMASK=255.255.255.224
ONBOOT=yes
3．配置文件keepalived.conf
! Configuration File for keepalived
global_defs {
notification_email {
#swm9988@gmail.com
}
#notification_email_from swm9988@gmail.com
#smtp_server 127.0.0.1
# smtp_connect_timeout 30
router_id LVS_DEVEL
}
# VIP1
vrrp_instance VI_1 {
state MASTER #备份服务器上将MASTER改为BACKUP
interface eth0
virtual_router_id 51
priority 100 # 备份服务上将100改为99
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.0.181
#(如果有多个VIP，继续换行填写.)
}
}
virtual_server 192.168.0.181 80 {
delay_loop 6 #(每隔10秒查询realserver状态)
lb_algo wrr #(lvs 算法,rr,wrr-轮询,lc,wlc-最少连接)
lb_kind DR #(Direct Route,NAT,TUN)
persistence_timeout 60 #(同一IP的连接60秒内被分配到同一台realserver)
protocol TCP #(用TCP协议检查realserver状态)
real_server 192.168.0.185 80 {
weight 3 #(权重)
TCP_CHECK {
connect_timeout 10 #(10秒无响应超时)
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
real_server 192.168.0.186 80 {
weight 3
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
}
四、运行
1.Rn服务器运行Rs.sh start
2.LVS服务器安装后重启service keepalived start
运行watch ipvsadm –Ln，查看服务状态
（本方案真实安装服务器并在生产中运行，没有任何问题，当然真实项目中还有相关的防火墙设置的其他操作，希望可以帮助有需要的各位）
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