一、常用的負載均衡軟件：
Nginx 應用層負載
LVS 網絡層負載
HAProxy 應用層負載
常用的負載均衡硬件：
F5 、Netscale
二、LVS的四種工作模式
1）VS/NAT模式（Network address translation）
通過NAT轉換表進行負載，收包和回包都需要查表
2）VS/TUN模式（tunneling）
給數據包打上IP頭
3）DR模式（Direct routing）
給數據包打上MAC頭
4）fulnat
雙重NAT轉換
三、LVS的配置（NAT模式）
三臺主機，一臺作爲負載轉發（dir），兩臺作爲業務（rs）
hostname dir
loginout
hostname rs1
loginout
hostname rs2
loginout
===============dir配置
yum install ipvsadm -y #dir上安裝ipvsadm包 vim /usr/local/sbin/lvs_nat.sh #! /bin/bash# director 服務器上開啓路由轉發功能: echo 1 > /proc/sys/net/ipv4/ip_forward # 關閉icmp的重定向echo 0 > /proc/sys/net/ipv4/conf/all/send_redirectsecho 0 > /proc/sys/net/ipv4/conf/default/send_redirectsecho 0 > /proc/sys/net/ipv4/conf/eth0/send_redirectsecho 0 > /proc/sys/net/ipv4/conf/eth1/send_redirects # director 設置nat防火牆 iptables -t nat -F iptables -t nat -X iptables -t nat -A POSTROUTING -s 192.168.2.0/24 -j MASQUERADE #設置內網網段 # director設置ipvsadm IPVSADM='/sbin/ipvsadm' $IPVSADM -C $IPVSADM -A -t 192.168.1.200:80 -s rr $IPVSADM -a -t 192.168.1.200:80 -r 192.168.2.1:80 -m $IPVSADM -a -t 192.168.1.200:80 -r 192.168.2.2:80 -m /bin/bash /usr/local/sbin/lvs_nat.sh #執行腳本 ipvsadm -ln #查看虛擬轉發表 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 -> 192.168.2.1:80 Masq 1 0 0 -> 192.168.2.2:80 Masq 1 0 0
====================rs配置
yum install nginx -y #rs服務器上都安裝nginx作爲測試 echo "111master" > /usr/share/nginx/html/index.html yum install nginx -y echo "222slave" > /usr/share/nginx/html/index.html [root@dir ~]# curl 192.168.1.200:80 111master [root@dir ~]# curl 192.168.1.200:80 222slave [root@dir ~]# curl 192.168.1.200:80 111master [root@dir ~]# curl 192.168.1.200:80 222slave
測試成功
四、LVS的配置（DR模式）
ipvsadm -C ipvsadm -ln iptables -t nat -F #清空規則 rs網關不指向dir，三臺主機在同一網段，比較浪費公網IP，四個IP vim /usr/local/sbin/lvs_dr.sh #! /bin/bash echo 1 > /proc/sys/net/ipv4/ip_forward ipv=/sbin/ipvsadm vip=192.168.1.205 rs1=192.168.1.201 rs2=192.168.1.202 ifconfig eth0:0 $vip broadcast $vip netmask 255.255.255.255 up route add -host $vip dev eth0:0 $ipv -C $ipv -A -t $vip:80 -s rr $ipv -a -t $vip:80 -r $rs1:80 -g -w 1 $ipv -a -t $vip:80 -r $rs2:80 -g -w 1 /bin/bash /usr/local/sbin/lvs_dr.sh #執行腳本 ipvsadm -ln #查看規則
====================兩臺上rs配置
#! /bin/bash vip=192.168.1.205 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 /bin/bash /usr/local/sbin/lvs_dr_rs.sh
測試：最好再開一臺Linux，瀏覽器有緩存
五、LVS+keepalived
兩臺作爲keepalived，一主一從，dir和rs2做主從keepalive
[root@dir ~]# ipvsadm -C
#清空規則
yum install -y keepalived ipvsadm
#dir和rs2安裝
cp /etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf.bak
> /etc/keepalived/keepalived.conf
vim /etc/keepalived/keepalived.conf
#dir上編譯配置文件
vrrp_instance VI_1 {
state MASTER #備用服務器上爲 BACKUP
interface eth0
virtual_router_id 51
priority 100 #備用服務器上爲90
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.1.205
}
}
virtual_server 192.168.1.205 80 {
delay_loop 6 #(每隔10秒查詢realserver狀態)
lb_algo wlc #(lvs 算法)
lb_kind DR #(Direct Route)
persistence_timeout 60 #(同一IP的連接60秒內被分配到同一臺realserver)
protocol TCP #(用TCP協議檢查realserver狀態)
real_server 192.168.1.201 80 {
weight 100 #(權重)
TCP_CHECK {
connect_timeout 10 #(10秒無響應超時)
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
real_server 192.168.1.202 80 {
weight 100
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
}
/etc/init.d/keepalived start #啓動
正在啓動 keepalived： [確定]
ip add #查看虛擬IP是否啓動
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:e2:dc:da brd ff:ff:ff:ff:ff:ff
inet 192.168.1.200/24 brd 192.168.1.255 scope global eth0
inet 192.168.1.205/32 scope global eth0
inet6 fe80::20c:29ff:fee2:dcda/64 scope link
valid_lft forever preferred_lft forever===================從keeplived配置
cp /etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf.bak
> /etc/keepalived/keepalived.conf
vim /etc/keepalived/keepalived.conf
vrrp_instance VI_1 {
state BACKUP #備用服務器上爲 BACKUP
interface eth0
virtual_router_id 51
priority 90 #備用服務器上爲90
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.1.205
}
}
virtual_server 192.168.1.205 80 {
delay_loop 6 #(每隔10秒查詢realserver狀態)
lb_algo wlc #(lvs 算法)
lb_kind DR #(Direct Route)
persistence_timeout 60 #(同一IP的連接60秒內被分配到同一臺realserver)
protocol TCP #(用TCP協議檢查realserver狀態)
real_server 192.168.1.201 80 {
weight 100 #(權重)
TCP_CHECK {
connect_timeout 10 #(10秒無響應超時)
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
real_server 192.168.1.202 80 {
weight 100
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
}
/etc/init.d/keepalived start
/etc/init.d/ipvsadm start
=====================
啓動兩臺rs的Nginx服務，若下面規則缺少，查看Iptables是否關閉
[root@dir ~]# ipvsadm -ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
TCP 192.168.1.205:80 wlc persistent 60
-> 192.168.1.201:80 Route 100 0 0
-> 192.168.1.202:80 Route 100 0 0
成功
宕機測試：
關閉rs1的業務網卡
[root@dir ~]# ipvsadm -ln IP Virtual Server version 1.2.1 (size=4096) Prot LocalAddress:Port Scheduler Flags -> RemoteAddress:Port Forward Weight ActiveConn InActConn TCP 192.168.1.205:80 wlc persistent 60 -> 192.168.1.202:80 Route 100 0 0 再開啓 [root@dir ~]# ipvsadm -ln IP Virtual Server version 1.2.1 (size=4096) Prot LocalAddress:Port Scheduler Flags -> RemoteAddress:Port Forward Weight ActiveConn InActConn TCP 192.168.1.205:80 wlc persistent 60 -> 192.168.1.201:80 Route 100 0 0 -> 192.168.1.202:80 Route 100 0 0
keeplived高可用測試
/etc/init.d/keepalived stop #關閉主 [root@rs2 ~]# ipvsadm -ln IP Virtual Server version 1.2.1 (size=4096) Prot LocalAddress:Port Scheduler Flags -> RemoteAddress:Port Forward Weight ActiveConn InActConn TCP 192.168.1.205:80 wlc persistent 60 -> 192.168.1.201:80 Route 100 0 0 -> 192.168.1.202:80 Local 100 0 0
成功