一、LVS負載均衡linux
實現LVS負載均衡轉發方式有三種,分別爲NAT、DR、TUN模式,LVS均衡算法包括:RR(round-robin)、LC(least_connection)、W(weight)RR、WLC模式等(RR爲輪詢模式,LC爲最少鏈接模式)。算法
LVS NAT原理:用戶請求LVS VIP到達director,director將請求的報文的目標IP地址改爲後端的realserver IP地址,同時將報文的目標端口也改爲後端選定的realserver相應端口,最後將報文發送到realserver,realserver將數據返給director,director再把數據發送給用戶。(兩次請求都通過director,因此訪問大的話,director會成爲瓶頸)shell
LVS DR原理:用戶請求LVS VIP到達director,director將請求的報文的目標MAC地址改爲後端的realserver MAC地址,目標IP爲VIP(不變),源IP爲用戶IP地址(保持不變),而後Director將報文發送到realserver,realserver檢測到目標爲本身本地VIP,若是在同一個網段,而後將請求直接返給用戶。若是用戶跟realserver不在一個網段,則經過網關返回用戶後端
LVS TUN原理:用戶請求LVS到達director,director經過IP-TUN加密技術將請求的報文的目標MAC地址改爲後端的realserver MAC地址,目標IP爲VIP(不變),源IP爲用戶IP地址(保持不變),而後Director將報文發送到realserver,realserver基於IP-TUN解密,而後檢測到目標爲本身本地VIP,若是在同一個網段,而後將請求直接返給用戶。若是用戶跟realserver不在一個網段,則經過網關返回用戶bash
二、LVS負載均衡配置服務器
1)Ipvsadm編譯安裝方法以下負載均衡
wget -c http://www.linuxvirtualserver.org/software/kernel-2.6/ipvsadm-1.24.tar.gz ln -s /usr/src/kernels/2.6.* /usr/src/linux yum install -y libnl* popt*
tar xzvf ipvsadm-1.24.tar.gz cd ipvsadm-1.24 make make install
2)Ipvsadm軟件安裝完畢後,須要進行配置,主要配置方法有三步:添加虛擬服務器IP,添加realserver後端服務及啓動LVS服務器VIP地址,配置代碼以下:tcp
ipvsadm -A -t 192.168.0.188:80 -s rr ipvsadm -a -t 192.168.0.188:80 -r 192.168.0.112 -g -w 2 ipvsadm -a -t 192.168.0.188:80 -r 192.168.0.113 -g -w 2
3)shell腳本部署LVS相關軟件加密
#!/bin/bash SNS_VIP=$2 SNS_RIP1=$3 SNS_RIP2=$4 if [ "$1" == "stop" -a -z "$2" ];then echo "------------------------------------------" echo -e "\033[32mPlease Enter $0 stop LVS_VIP\n\nEXample:$0 stop 192.168.1.111\033[0m" echo exit else if [ -z "$2" -a -z "$3" -a -z "$4" ];then echo "----------------------------------------" echo -e "\033[32mPlease Enter Input $0 start VIP REALSERVER1 REALSERVER2\n\nEXample:$0 start/stop 192.168.1.111 192.168.1.2 192.168.1.3\033[0m" echo exit 0 fi fi . /etc/rc.d/init.d/functions logger $0 called with $1 function IPVSADM(){ /sbin/ipvsadm --set 30 5 60 /sbin/ifconfig eth0:0 $SNS_VIP broadcast $SNS_VIP netmask 255.255.255.255 broadcast $SNS_VIP up /sbin/route add -host $SNS_VIP dev eth0:0 /sbin/ipvsadm -A -t $SNS_VIP:80 -s wlc -p 120 /sbin/ipvsadm -a -t $SNS_VIP:80 -r $SNS_RIP1:80 -g -w 1 /sbin/ipvsadm -a -t $SNS_VIP:80 -r $SNS_RIP2:80 -g -w 1 } case "$1" in start) IPVSADM echo "-----------------------------------------------------" /sbin/ipvsadm -Ln touch /var/lock/subsys/ipvsadm > /dev/null 2>&1 ;; stop) /sbin/ipvsadm -C /sbin/ipvsadm -Z ifconfig eth0:0 down >>/dev/null 2>&1 route del $SNS_VIP >>/dev/null 2>&1 rm -rf /var/lock/subsys/ipvsadm > /dev/null 2>&1 echo "ipvsadm stopped!" ;; status) if [ ! -e /var/lock/subsys/ipvsadm ] then echo "ipvsadm stopped!" exit 1 else echo "ipvsadm started!" fi ;; *) echo "Usage: $0 {start | stop | status}" exit 1 esac exit 0
4)LVS服務器綁定VIP地址,命令以下spa
VIP=192.168.0.190 ifconfig eth0:0 $VIP netmask 255.255.255.255 broadcast $VIP /sbin/route add -host $VIP dev eth0:0
5)LVS ipvsadm配置參數說明
-A 增長一臺虛擬服務器VIP地址; -t 虛擬服務器提供的是tcp服務; -s 使用的調度算法; -a 在虛擬服務器中增長一臺後端真實服務器; -r 指定真實服務器地址; -w 後端真實服務器的權重; -m 設置當前轉發方式爲NAT模式;-g爲直接路由模式;-i 模式爲隧道模式。
6)查看LVS轉發列表命令爲:ipvsadm -Ln
7)Nginx客戶端realserver配置VIP腳本
#!/bin/sh #LVS Client Server VIP=192.168.0.188 case $1 in start) ifconfig lo:0 $VIP netmask 255.255.255.255 broadcast $VIP /sbin/route add -host $VIP dev 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 sysctl -p >/dev/null 2>&1 echo "RealServer Start OK" exit 0 ;; stop) ifconfig lo:0 down route del $VIP >/dev/null 2>&1 echo "0">/proc/sys/net/ipv4/conf/lo/arp_ignore echo "0">/proc/sys/net/ipv4/conf/lo/arp_announce echo "0">/proc/sys/net/ipv4/conf/all/arp_ignore echo "0">/proc/sys/net/ipv4/conf/all/arp_announce echo "RealServer Stoped OK" exit 1 ;; *) echo "Usage: $0 {start|stop}" ;; esac