說明：本篇結合上一篇"linux-叢集介紹"而寫，當看完上一篇叢集介紹後做這個實驗思路将會很清晰！！！
負載均衡：LVS-NAT實作：
實驗環境：
1 三台RHEL5.4虛拟機，二台作安裝好web作為後端Realserver，另一台作為Director，Realserver的網關都指向Director，
2 Director上需要二個網卡，一個公網位址向外提供服務，一個内網位址可以是私有位址與Realserver通信。Director上開啟路由轉發功能。
3 Realserver ip 192.168.0.55/192.168.0.56，網關192.168.0.100
Director ip 外網卡：10.0.0.10，内網卡192.168.0.100
<a target="_blank" href="http://blog.51cto.com/attachment/201102/015352335.png"></a>
配置好Realserver上的ip和網關，開啟web服務，主要在Director上配置
ipvsadm -A -t 10.0.0.10:80 -s wlc
ipvsadm -a -t 10.0.0.10：80 -r 192.168.0.55 -m -w 2
ipvsadm -a -t 10.0.0.10：80 -r 192.168.0.56 -m -w 5
vim /etc/sysctl
net.ipv4.ip_forward = 1 #開啟路由轉發
LVM-nat的腳本
#!/bin/bash
# case “$1”in
start)
ipvsadm -A -t 192.168.0.83:80 -s wlc
ipvsadm -a -t 192.168.0.83:80 -r 192.168.10.6 -m -w 2
ipvsadm -a -t 192.168.0.83:80 -r 192.168.10.7 -m -w 5 ;;
stop)
ipvsadm –C ;;
status)
ipvadm -Ln ;;
esac
ipvsadm –Ln 檢視所有連接配接 ipvsadm –E 192.168.0.83::80 –s wrr (基于權重，權重大的連接配接将多)
負載均衡 LVS-DR server
1 三台RHEL5.4虛拟機，二台作安裝好web作為後端Realserver，另一台作為Director
2 Director上需要一個網卡，位址都為公網位址，VIP必須是公網位址，RIP可以是私網位址但要與Director通信時要進行解析。是以這裡全部使用公網位址，不需要指定網關
Director上開啟路由轉發功能。
3 Realserver ip 192.168.0.55/192.168.0.56，
Director ip 192.168.0.100 VIP 192.168.0.200
當用戶端送出請求時reserver都會響應，為避免realserver都響應可以：
1 通過防火牆不讓arp資料包進來
2 linux核心有二個參數，配置完後避免arp請求
<a target="_blank" href="http://blog.51cto.com/attachment/201102/015431236.png"></a>
配置過程：
在兩個Rserver上各配置vip
ifconfig lo:0 192.168.0.200 broadcast 192.168.0.200 netmask 255.255.255.255 up
在二個Rserver上配置路由資訊通過lo:0接口才出去
route add -host 192.168.0.200 dev lo:0
在二個web伺服器上做位址隐藏 vim /etc/sysctl.conf
vim /etc/sysctl.conf 位址隐藏
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 重新讀取配置檔案
Directory上配置
ifconfig eth0:0 192.168.0.100 broadcast 192.168.0.100 netmask 255.255.255.255 up
ipvsadm -A -t 192.168.0.200:80 -s wlc
ipvsadm -a -t 192.0.200:80 -r 192.168.0.55 -g -w 5
ipvsadm -a -t 192.0.200:80 -r 192.168.0.56 -g -w 8
server ipvsadm save
二個Realserver可以通過一個nfs伺服器共享網站資源，是二個Realserver的網站内容同步提供同樣的網站内容
Director腳本:
# LVS script for VS/DR
. /etc/rc.d/init.d/functions
VIP=192.168.0.200
RIP1=192.168.0.55
RIP2=192.168.0.56
PORT=80
case "$1" in
start)
/sbin/ifconfig eth0:1 $VIP broadcast $VIP netmask 255.255.255.255 up
/sbin/route add -host $VIP dev eth0:1
# Since this is the Director we must be able to forward packets
echo 1 > /proc/sys/net/ipv4/ip_forward
# Clear all iptables rules.
/sbin/iptables -F
# Reset iptables counters.
/sbin/iptables -Z
# Clear all ipvsadm rules/services.
/sbin/ipvsadm -C
# Add an IP virtual service for VIP 192.168.0.200 port 80
# In this recipe, we will use the round-robin scheduling method.
# In production, however, you should use a weighted, dynamic scheduling method.
/sbin/ipvsadm -A -t $VIP:80 -s wlc
# Now direct packets for this VIP to
# the real server IP (RIP) inside the cluster
/sbin/ipvsadm -a -t $VIP:80 -r $RIP1 -g -w 1
/sbin/ipvsadm -a -t $VIP:80 -r $RIP2 -g -w 2
/bin/touch /var/lock/subsys/ipvsadm &> /dev/null
;;
# Stop forwarding packets
echo 0 > /proc/sys/net/ipv4/ip_forward
# Reset ipvsadm
# Bring down the VIP interface
/sbin/ifconfig eth0:1 down
/sbin/route del $VIP
/bin/rm -f /var/lock/subsys/ipvsadm
echo "ipvs is stopped..."
if [ ! -e /var/lock/subsys/ipvsadm ]; then
echo "ipvsadm is stopped ..."
else
echo "ipvs is running ..."
ipvsadm -L -n
fi
*)
echo "Usage: $0 {start|stop|status}"
RealServer腳本:
# Script to start LVS DR real server.
# description: LVS DR real server
host=`/bin/hostname`
# Start LVS-DR real server on this machine.
/sbin/ifconfig lo down
/sbin/ifconfig lo up
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
/sbin/ifconfig lo:0 $VIP broadcast $VIP netmask 255.255.255.255 up
/sbin/route add -host $VIP dev lo:0
# Stop LVS-DR real server loopback device(s).
/sbin/ifconfig lo:0 down
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
# Status of LVS-DR real server.
islothere=`/sbin/ifconfig lo:0 | grep $VIP`
isrothere=`netstat -rn | grep "lo:0" | grep $VIP`
if [ ! "$islothere" -o ! "isrothere" ];then
# Either the route or the lo:0 device
# not found.
echo "LVS-DR real server Stopped."
else
echo "LVS-DR real server Running."
fi
# Invalid entry.
echo "$0: Usage: $0 {start|status|stop}"
exit 1
本文轉自 張玉坡 51CTO部落格，原文連結:http://blog.51cto.com/fighter/499181
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