LVS

office documentation：

http://www.linuxvirtualserver.org/VS-DRouting.html

http://wenku.baidu.com/view/f352412e2af90242a895e565.html

http://wenku.baidu.com/view/30f7115c3b3567ec102d8abb.html?re=view

http://wenku.baidu.com/view/f13a142c453610661ed9f41e.html

http://wenku.baidu.com/view/b9c7cd52f01dc281e53af027.html

LVS DR(direct routing):性能最好

server	ip(eth0)	vip
director server	192.168.1.105	eth0:0 192.168.1.111
real server 1	192.168.1.102	lo:0 192.168.1.111
real server 2	192.168.1.104	lo:0 192.168.1.111

1. install lvs on director server

   wget http://www.linuxvirtualserver.org/software/kernel-2.6/ipvsadm-1.26.tar.gz

   tar xzvf ipvsadm-1.26.tar.gz

   cd ipvsadm-1.26

   ln -s /usr/src/kernels/$(uname -r) /usr/src/linux #注意内核版本号，编译时lvs通过linux软连接找到相应的头文件和库文件

   make

   make install

2. check lvs

   ipvsadm

   lsmod | grep -i ip_vs #you cannot check the ipvsadm by "ps -ef | grep ipvsadm"

3. change the kernel parameters on network in /etc/sysctl.conf

   net.ipv4.ip_forward = 0

   net.ipv4.conf.all.send_redirects = 1

   net.ipv4.conf.eth0.send_redirects = 1

   net.ipv4.conf.default.send_redirects = 1

   sysctl -p   #生效

   sysctl -a   #检测参数值

4. 配置VIP和路由

   ifconfig eth0:0 192.168.1.111 broadcast 192.168.1.111 netmask 255.255.255.255 up

   route add -host 192.168.1.111 dev eth0:0

5. 配置lvs（通过ipvsadm配置，就像netfilter是通过iptables配置的一样）

   ipvsadm -C

   ipvsadm -A -t 192.168.1.111:80 -s rr #add a vitual ip and port,and use round-robin

   ipvsadm -a -t 192.168.1.111:80 -r 192.168.1.102:80 -g

   ipvsadm -a -t 192.168.1.111:80 -r 192.168.1.104:80 -g

6. 启动lvs

   ipvsadm

   ipvsadm -ln  #check lvs状态

   ====================================================================================

   work on real server 1 and 2, the same setup on both 1 and 2

7. change kernel parmater on network in /etc/sysctl.conf

   net.ipv4.ip_forward = 0

   net.ipv4.conf.lo.arp_ignore = 1

   net.ipv4.conf.lo.arp_announce = 2

   net.ipv4.conf.all.arp_ignore = 1

   net.ipv4.conf.all.arp_announce = 2

   
   

   sysctl -p  #生效

   sysctl -a  #confirm

8. 配置VIP&路由

   ifconfig lo:0 192.168.1.111 broadcast 192.168.1.111 netmask 255.255.255.255 up

   route add -host 192.168.1.111 dev lo:0

9. start web server

   nginx

   =====================================================================================

   work on client end to test

   open 10 tabs to access http://192.168.1.111

   =====================================================================================

   work on director server

10. stop lvs

    ipvsadm -C

    ifconfig eth0:0 down

11. caution: in prd env, use script to configure LVS's start and stop