LVS (Linux Virtual Server)是一种集群(Cluster)技术，采用IP负载均衡技术和基于内容请求分发技术。LVS可以实现LINUX平台下的简单负载均衡。
其中LVS/NAT是一种最简单的方式，所有的RealServer只需要将自己的网关指向Director即可。
LVS负载均衡的NAT模式
一、实验准备
在VMware Workstation虚拟机环境下，准备三台服务器，一台作为director, 两台作为real server。
二、网络配置
director需要配置两块网卡，一块（eth0）与real server连接的内网，另外一块（eth1）连接到公网。
配置参考如下：
director：eth0 192.168.20.28/24 （内网）
eth1 192.168.1.33/24 （外网）
real server1：eth0 192.168.20.138
real server2：eth0 192.168.20.250
这三台服务器在192.168.20.0/24能互相通信
实现方法：
1、虚拟机网络模式选择【自定义VMnet1】，在这里的LVS-NAT实验中需要设置director的eth0和两台real server的eth0为自定义VMnet1模式，而director的eth1则设置为桥接模式，可以直接使用外网。
2、客户机Windows机器上VMnet1的IP设置，设置成与LVS的三台服务器eth0的IP在同一个网段，目的是为了能与三台LVS服务器通信，方便做试验
3、具体配置如下，real server1、2的网关均指向192.168.20.28
director：
real server1：
real server2：
三、LVS/NAT 配置
1、安装epel扩展源、nginx（测试用）（nginx在real server下安装）
wget /fedora-epel/6/i386/epel-release-6-8.noarch.rpm
[root@realserver1 ~]# yum -y install nginx
2、测试页面
[root@realserver1 ~]# echo "sr1-192.168.20.138" >/usr/share/nginx/html/index.html
[root@realserver2 ~]# echo "sr2-192.168.20.250" >/usr/share/nginx/html/index.html
3、Director 下安装ipvsadm
[root@director ~]# yum -y install ipvsadm
4、配置ipvsadm，创建/usr/local/sbin/lvs_nat.sh脚本
LVS的调度算法：轮叫调度(Round Robin)(简称rr) ,加权轮叫(Weighted Round Robin)(简称wrr),最少链接(least connection)(LC),加权最少链接(Weighted Least Connections)(WLC) 等
5、开启nat服务
[root@director ~]# sh /usr/local/sbin/lvs_nat.sh
6、测试LVS/NAT，由于sr1的权值为2，所以响应的请求为sr1的两倍
在windows下访问
LVS负载均衡的DR模式配置
[root@director ~]# ipvsadm -C
[root@director ~]# ipvsadm -ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
[root@director ~]# iptables -t nat -F
一、网络配置
director：eth0
realserver1：eth0
realserver2：eth0
二、LVS/DR 配置
1、Director配置
[root@director ~]# vim /usr/local/sbin/lvs_dr.sh
执行脚本：
[root@director ~]# sh /usr/local/sbin/lvs_dr.sh
2、在两台realserver配置
[root@realserver1 ~]# vim /usr/local/sbin/lvs_dr_rs.sh
#! /bin/bash
vip=192.168.1.200
ifconfig lo:0 $vip broadcast $vip netmask 255.255.255.255 up
route add -host $vip lo:0
echo "1" >/proc/sys/net/ipv4/conf/lo/arp_ignore
echo "2" >/proc/sys/net/ipv4/conf/lo/arp_announce
echo "1" >/proc/sys/net/ipv4/conf/all/arp_ignore
echo "2" >/proc/sys/net/ipv4/conf/all/arp_announce
执行脚本：
[root@realserver1 ~]# ifconfig lo:0
lo:0 Link encap:Local Loopback
inet addr:192.168.1.200 Mask:255.255.255.255
UP LOOPBACK RUNNING MTU:65536 Metric:1
[root@realserver2 ~]# ifconfig lo:0
lo:0 Link encap:Local Loopback
inet addr:192.168.1.200 Mask:255.255.255.255
UP LOOPBACK RUNNING MTU:16436 Metric:1
3、测试，在第四台机器上访问
[root@sh ~]# elinks 192.168.1.200
4、更改权值
[root@director ~]# vim /usr/local/sbin/lvs_dr.s
[root@director ~]# sh /usr/local/sbin/lvs_dr.sh
测试：
LVS结合Keepalived配置
两台director，两台realserver
[root@director ~]# ipvsadm -C
[root@director ~]# ifconfig eth0:0 down
[root@director network-scripts]# rm -rf ifcfg-eth0:0
一、安装keepalived
[root@director ~]# yum -y install keepalived
二、备用director
1、安装ipvsadm、keepalived
[root@sh ~]# yum -y install ipvsadm
[root@sh ~]# yum -y install keepalived
2、配置keepalived
[root@director ~]# vim /etc/keepalived/keepalived.conf
vrrp_instance VI_1 {
state MASTER #备用服务器上为 BACKUP
interface eth0
virtual_router_id 51
priority 100 #备用服务器上为90
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.1.200
}
}
virtual_server 192.168.1.200 80 {
delay_loop 6 #(每隔10秒查询realserver状态)
lb_algo rr #(lvs 算法)
lb_kind DR #(Direct Route)
persistence_timeout 0 #(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 192.168.1.138 80 {
weight 100 #(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 192.168.1.250 80 {
weight 100
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
}
3、备用director配置keepalived
scp到备用director
[root@director ~]# yum -y install openssh-clients
[root@director ~]# scp /etc/keepalived/keepalived.conf 192.168.1.218:/etc/keepalived/keepalived.conf
[root@sh ~]# vim /etc/keepalived/keepalived.conf
vrrp_instance VI_1 {
state BACKUP #备用服务器上为 BACKUP
interface eth0
virtual_router_id 51
priority 99 #备用服务器上为90
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.1.200
}
}
virtual_server 192.168.1.200 80 {
delay_loop 6 #(每隔10秒查询realserver状态)
lb_algo rr #(lvs 算法)
lb_kind DR #(Direct Route)
persistence_timeout 0 #(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 192.168.1.138 80 {
weight 100 #(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 192.168.1.250 80 {
weight 100
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
}
三、director启动keepalived
[root@director ~]# /etc/init.d/keepalived start （主）
Starting keepalived: [ OK ]
[root@sh ~]# /etc/init.d/keepalived start （从）
Starting keepalived: [ OK ]
查看ipvsadm状态
[root@director ~]# ipvsadm -ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
TCP 192.168.1.200:80 rr
-> 192.168.1.138:80 Route 100 0 7
-> 192.168.1.250:80 Route 100 0 16
[root@director ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:92:99:4d brd ff:ff:ff:ff:ff:ff
inet 192.168.1.28/24 brd 192.168.1.255 scope global eth0
inet 192.168.1.200/32 scope global eth0
inet6 fe80::20c:29ff:fe92:994d/64 scope link
valid_lft forever preferred_lft forever
四、两台realserver启动dr脚本/usr/local/sbin/lvs_dr_rs.sh
[root@realserver1 ~]# sh /usr/local/sbin/lvs_dr_rs.sh
[root@realserver2 ~]# sh /usr/local/sbin/lvs_dr_rs.sh
五、测试，在第五台机器上访问vip192.168.1.200
nginx的负载均衡集群
清除之前的配置
[root@director ~]# ipvsadm -C
[root@director ~]# iptables -F
[root@director ~]# /etc/init.d/keepalived stop
[root@director ~]# yum -y install nginx
[root@director ~]# vim /etc/nginx/conf.d/lb.conf //配置虚拟主机
upstream test {
server 192.168.1.138:80;
server 192.168.1.250:80;
}
server {
listen 80;
server_name ;
location / {
proxy_pass http://test/;
proxy_set_header Host $host;
# proxy_set_header X-Real-IP $remote_addr;
# proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}
}
[root@director ~]# netstat -ntlp |grep nginx
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 11205/nginx
测试：
[root@director ~]# curl -xlocalhost:80
sr2-192.168.20.250
[root@director ~]# curl -xlocalhost:80
sr1-192.168.20.138
[root@director ~]# curl -xlocalhost:80
sr2-192.168.20.250
[root@director ~]# curl -xlocalhost:80
sr1-192.168.20.138
[root@director ~]# curl -xlocalhost:80
sr2-192.168.20.250
[root@director ~]# curl -xlocalhost:80
sr1-192.168.20.138
设置权值
upstream test {
server 192.168.1.138:80weight=2;
server 192.168.1.250:80 weight=1;
}
server {
listen 80;
server_name ;
location / {
proxy_pass http://test/;
proxy_set_header Host $host;
# proxy_set_header X-Real-IP $remote_addr;
# proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}
}
[root@director ~]# curl -xlocalhost:80
sr1-192.168.20.138
[root@director ~]# curl -xlocalhost:80
sr2-192.168.20.250
[root@director ~]# curl -xlocalhost:80
sr1-192.168.20.138
[root@director ~]# curl -xlocalhost:80
sr1-192.168.20.138
[root@director ~]# curl -xlocalhost:80
sr2-192.168.20.250
[root@realserver2 ~]# nginx -s stop
[root@director ~]# curl -xlocalhost:80
sr1-192.168.20.138
[root@director ~]# curl -xlocalhost:80
sr1-192.168.20.138
[root@director ~]# curl -xlocalhost:80
sr1-192.168.20.138
[root@director ~]# curl -xlocalhost:80
sr1-192.168.20.138
[root@director ~]# curl -xlocalhost:80
sr1-192.168.20.138
[root@realserver2 ~]# nginx
[root@director ~]# curl -x192.168.1.28:80
sr2-192.168.20.250
[root@director ~]# curl -x192.168.1.28:80
sr1-192.168.20.138
[root@director ~]# curl -x192.168.1.28:80
sr1-192.168.20.138
[root@director ~]# curl -x192.168.1.28:80
sr2-192.168.20.250
本文转自 HMLinux 51CTO博客，原文链接:/7424593/1730693
