（1）本次基于VMware Workstation搭建一个四台Linux（CentOS 7.4）系统所构成的一个服务器集群，其中两台负载均衡服务器（一台为主机，另一台为备机），另外两台作为真实的Web服务器（向外部提供http服务，这里仅仅使用了CentOS默认自带的http服务，没有安装其他的类似Tomcat、Jexus服务）。
（2）本次实验基于DR负载均衡模式，设置了一个VIP（Virtual IP）为172.18.38.99，用户只需要访问这个IP地址即可获得网页服务。其中，负载均衡主机为172.18.38.100，备机为172.18.38.101。Web服务器A为172.18.38.200，Web服务器B为172.18.38.201。
[root@centos7-100 ~]# nmcli connection modify ens37 ipv4.addresses 172.18.38.100/16 ipv4.method manual connection.autoconnect yes
[root@centos7-101 ~]# nmcli connection modify ens37 ipv4.addresses 172.18.38.101/16 ipv4.method manual connection.autoconnect yes
[root@centos7-200 ~]# nmcli connection modify ens37 ipv4.addresses 172.18.38.200/16 ipv4.method manual connection.autoconnect yes
[root@centos7-201 ~]# nmcli connection modify ens37 ipv4.addresses 172.18.38.201/16 ipv4.method manual connection.autoconnect yes
利用chronyd服务同步时间
1，在四台主机上都执行下面的命令，注意时间服务器必须是一台
1，修改配置文件
vim /etc/chrony.conf
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
server 172.18.0.1 iburst #指定一台服务器
2，利用下面这条命令概略同步一下
ntpdate 172.18.0.1
1 Apr 13:23:31 ntpdate[8517]: adjust time server 172.18.0.1 offset -0.350642 sec
3，重启chrony服务
systemctl restart chronyd.service
systemctl disable firewalld
systemctl stop firewalld1，在两台lvs服务器下载keepalived
yum -y install keepalived1，keepvlived_master+lvs配置文件
vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
notification_email {
root@localhost #出问题了发邮件给谁
}
notification_email_from keepalived@localhost
smtp_server 127.0.0.1 #本机邮件服务器
smtp_connect_timeout 30 #超时时间
router_id proxy1 #服务器id
vrrp_mcast_group4 224.1.1.1 #多播地址所有的keepalived会在这个地址通讯，决定谁工作
}
vrrp_instance VI_1 {
state MASTER #主服务器
interface ens37 #网卡接口
virtual_router_id 66 #服务器id
priority 100 #优先级，
advert_int 1 #心跳检测 1秒一次
authentication { #验证
auth_type PASS #验证类型，基于密码
auth_pass 123456 #密码
}
virtual_ipaddress {
172.18.38.99/16 #共享IP
}
}
virtual_server 172.18.38.99 80 {
delay_loop 6
lb_algo rr #调度算法
lb_kind DR #调度模型
#persistence_timeout 50
protocol TCP
sorry_server 127.0.0.1 80
real_server 172.18.38.200 80 { #后端server_IP 及端口
weight 1 #权重
HTTP_GET { #健康检测方式
url {
path /
status_code 200
}
connect_timeout 3 #超时时间
nb_get_retry 3 #重试次数
delay_before_retry 3 #多长时间重试
}
}
real_server 172.18.38.201 80 {
weight 1
HTTP_GET {
url {
path /
status_code 200
}
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
}
}
}
2，keepalived_slave+lvs配置
vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
notification_email {
root@localhost
}
notification_email_from keepalived@localhost
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id proxy1
vrrp_mcast_group4 224.1.1.1
}
vrrp_instance VI_2 {
state SLAVE "slave关键配置"
interface ens37
virtual_router_id 88
priority 80
advert_int 1
authentication {
auth_type PASS
auth_pass 123456
}
virtual_ipaddress {
172.18.38.99/16
}
}
virtual_server 172.18.38.99 80 {
delay_loop 6
lb_algo rr
lb_kind DR
#persistence_timeout 50
protocol TCP
sorry_server 127.0.0.1 80
real_server 172.18.38.200 80 {
weight 1
HTTP_GET {
url {
path /
status_code 200
}
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
}
}
real_server 172.18.38.201 80 {
weight 1
HTTP_GET {
url {
path /
status_code 200
}
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
}
}
}
3，在两台lvs服务器下载ipvsadm包
yum install ipvsadm4，在两台lvs主机上都启动keepalived服务
systemctl start keepalived
systemctl enable keepalived5，注意这时候会在ens37网卡上加上一个新的IP
[root@centos7-lvs_master ~]# ip a
ens37: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:50:56:39:48:cc brd ff:ff:ff:ff:ff:ff
inet 172.18.38.101/16 brd 172.18.255.255 scope global ens37
valid_lft forever preferred_lft forever
inet 172.18.38.99/16 scope global secondary ens37
valid_lft forever preferred_lft forever
inet6 fe80::a7b9:b100:4f55:480e/64 scope link
valid_lft forever preferred_lft forever
[root@centos7-lvs_slave ~]# ip a
ens37: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:50:56:39:48:cc brd ff:ff:ff:ff:ff:ff
inet 172.18.38.101/16 brd 172.18.255.255 scope global ens37
valid_lft forever preferred_lft forever
inet 172.18.38.99/16 scope global secondary ens37
valid_lft forever preferred_lft forever
inet6 fe80::a7b9:b100:4f55:480e/64 scope link
valid_lft forever preferred_lft forever
5，查看调度规则
[root@centos7-lvs_master ~]# ipvsadm -ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
TCP 172.18.38.99:80 rr
-> 172.18.38.200:80 Route 1 0 4
-> 172.18.38.201:80 Route 1 0 4
[root@centos7-lvs_slave ~]# ipvsadm -ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
TCP 172.18.38.99:80 rr
-> 172.18.38.200:80 Route 1 0 0
-> 172.18.38.201:80 Route 1 0 0 1，安装httpd软件
1，安装httpd软件
yum install http
2，启动服务
systemctl start httpd
systemctl enable httpd
2，生成web页面，
A主机
echo web_server_A > /var/www/html/index.html
b主机
echo web_server_B > /var/www/html/index.html
2，在两个web服务器执行下面的脚本，会在lo网卡上生成一个vip
vim lvs_br_rs.sh
#!/bin/bash
#Author:wangxiaochun
#Date:2017-08-13
vip=172.18.38.99 "只需要修改一下IP即可"
mask=‘255.255.255.255‘
dev=lo:1
case $1 in
start)
echo 1 > /proc/sys/net/ipv4/conf/all/arp_ignore
echo 1 > /proc/sys/net/ipv4/conf/lo/arp_ignore
echo 2 > /proc/sys/net/ipv4/conf/all/arp_announce
echo 2 > /proc/sys/net/ipv4/conf/lo/arp_announce
ifconfig $dev $vip netmask $mask #broadcast $vip up
#route add -host $vip dev $dev
echo "The RS Server is Ready!"
;;
stop)
ifconfig $dev down
echo 0 > /proc/sys/net/ipv4/conf/all/arp_ignore
echo 0 > /proc/sys/net/ipv4/conf/lo/arp_ignore
echo 0 > /proc/sys/net/ipv4/conf/all/arp_announce
echo 0 > /proc/sys/net/ipv4/conf/lo/arp_announce
echo "The RS Server is Canceled!"
;;
*)
echo "Usage: $(basename $0) start|stop"
exit 1
;;
esac
3，查看lo网卡
[root@centos7-web_server_A ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet 172.18.38.99/32 scope global lo:1
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
[root@centos7-web_server_B ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet 172.18.38.99/32 scope global lo:1
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever1，不宕任何服务
[root@centos6 ~]# for i in {1..10};do sleep 0.5;curl 172.18.38.99;done
web_server_B
web_server_A
web_server_B
web_server_A
web_server_B
web_server_A
web_server_B
web_server_A
web_server_B
web_server_A
2，宕掉一台keepalived测试
[root@centos7 lvs_master ~]# systemctl stop keepalived.service
[root@centos6 ~]# for i in {1..10};do sleep 0.5;curl 172.18.38.99;done
web_server_B
web_server_A
web_server_B
web_server_A
web_server_B
web_server_A
web_server_B
web_server_A
web_server_B
web_server_A
测试通过
原文地址：http://blog.51cto.com/13598893/2093555
