LVS三种工作模式 、NAT模式和DR模式详细搭建过程

一、lvs三种工作模式
1.NAT模式：通过网络地址转换实现的虚拟服务器。Director Server将用户请求报文的目的地址改成选定的Real Server地址后，转发给Real Server，大并发访问时，Director Server的性能成为瓶颈
2.TUN模式：通过隧道模式实现虚拟服务器。Director Server采用隧道技术将请求发至Real Server后，Real Server直接相应客户端。
3.DR模式：直接使用路由技术是心啊虚拟服务器。通过改写请求报文的MAC地址，将请求发至Real Server，Real Server直接响应客户端。
最常用DR模式，其次nat模式。

二、lvs相关术语
1. DS：调度服务器 Director Server，指的是前端负载均衡器节点。
2. RS：真是服务器 Real Server。后端真实的工作服务器。
3. VIP：向外部直接面向用户请求，作为用户请求的目标的IP地址。
4. DIP：Director Server IP，调度器和真是服务器通讯的IP地址。
5. RIP：Real Server IP，后端真实服务器的IP地址。
6. CIP：Client IP，访问客户端的IP地址。

三、lvs十种调度算法
常用前四种
1.轮询（Round Robin）RR： 将客户端请求平均分发到Real Server。
2.加权轮询（Weighted Round Robin）WRR：根据Real Server 权重值进行轮询的调度。
3.最少连接（Least Connections）LC：选择连接最少的服务器。
4.加权最少连接（Weighted Least Connections）WLC：根据Real Server 权重值，选择连接数最少的服务器。
5.源地址散列（Source Hashing）SH：根据请求的源IP地址，作为散列键（Hash Key）从静态分配的散列表找出对应的服务器。
6.目标地址散列调度（Destination Hashing ） DH：与SH相反的是，DH根据请求的目标IP地址，作为散列键（Hash Key）从静态分配的散列表找出对应的服务器。
7.基于局部性的最少链接（Locality-Based Least Connections）LBLC：主要是针对请求报文的目标IP地址的负载均衡调度，目前主要使用Cache集群系统。LBLC调度算法先根据请求的目标IP地址找出该目标IP地址最近使用的服务器，若该服务器时可以用的且没有超载，将请求发送到该服务器，若服务器不存在，或者该服务器超载且有服务器处于一半的工作负载，则使用“LC最少连接”的原则选出一个可用的服务器，将请求发送到服务器。
8.带复制的基于局部性的最少连接（Locality-Based Least Connections with Replication）LBLCR：算法也是针对目标IP地址的负载均衡，目前也主要用于Cache集群系统。它与LBLC算法不通之处时它要维护从一个目标IP地址到一组服务器的映射，而LBLC算法维护从一个目标IP地址到一台服务器的映射。
9.最短的期望的延迟调度（Shortest Expected Delay） SED：SED基于WLC算法，将请求以最短的期望的延迟方式到服务器，计算当前realserver 的负载情况计算方法：（active+1）*256/weight=overhead。
10.最少队列调度（Never Queue）NQ：如果realserver的连接数等于0就直接分配到该服务器，但是此服务器并不一定是最快的那台，如果所有服务器都是繁忙状态，它采取最短的期望延迟分配请求。

四、部署LVS的NAT模式
方案
 

 IP地址主机名
客户端eth0(cip)  192.168.4.100vmctl5
调度器

eth0(vip)  192.168.4.5

eth1(dip)  192.168.2.5

vmctl1
后端服务器1

eth0(rip)  192.168.2.100

网关配置成 192.168.2.5

vmctl2
后端服务器2

etho(rip)  192.168.2.200

网关配置成 192.168.2.5

vmctl3

使用4台虚拟机，1台作为Director调度器、2台Real Server、1台客户端，结构如下图所示：

ipvsadm相关命令

ipvsadm -A  添加虚拟服务器   ipvsadm -a 添加真实服务器

ipvsadm -E 修改虚拟服务器    ipvsadm -e 修改真实服务器

ipvsadm -D 删除虚拟服务器    ipvsadm -d 删除真是服务器

ipvsadm -C 清空所有               ipvsadm -L 查看LVS规则表

-s [rr|wrr|lc|wlc]  指定集群算法

ipvsadm -a -t|u 192.168.4.5:8080 -r 192.168.2.100 [-g|i|m] [-w 权重] 添加真实服务器-g DR模式，-i 隧道模式，-m NAT模式

ipvsadm -e -t|u 192.168.4.5:8080 -r 192.168.2.100 [-g|i|m] [-w 权重] 修改真实服务器

ipvsadm -d -t|u 192.168.4.5:8080 -r 192.168.2.100  删除真实服务器

ipvsadm -Ln 查看LVS规则表

1、后端服务器1 vmctl2 部署

#1、配置网卡信息
[root@vmctl2 ~]# cat  /etc/sysconfig/network-scripts/ifcfg-eth0
NAME=eth0
DEVICE=TYPE=Ethernet
IPADDR=192.168.2.100
NATMASK=255.255.255.0
ONBOOT=yes
BOOTPROTO=static
GATEWAY=192.168.2.5 #网关配置成调度器的dip
#2、启动tomcat，并访问测试页面
[root@vmctl2 ~]# /mnt/apache-tomcat-8.0.30/bin/startup.sh  
[root@vmctl2 ~]# cat /mnt/apache-tomcat-8.0.30/webapps/ipvnat/index.html 
192.168.2.100
[root@vmctl2 ~]# curl http://192.168.2.100:8080/ipvnat/index.html
192.168.2.100
[root@vmctl2 ~]# cat /mnt/apache-tomcat-8.0.30/logs/localhost_access_log.2020-06-29.txt 
192.168.2.100 - - [29/Jun/2020:04:40:18 -0700] "GET /ipvnat/index.html HTTP/1.1" 200 14

2、后端服务器2  vmctl3 部署

#配置网卡信息
[root@vmctl3 ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth0
NAME=eth0
DEVICE=eth0
TYPE=Ethernet
IPADDR=192.168.2.200
NATMASK=255.255.255.0
ONBOOT=yes
BOOTPROTO=static
GATEWAY=192.168.2.5 #网关配置成调度器的dip

#启动tomcat，并测试
[root@vmctl3 ~]# /mnt/apache-tomcat-8.0.30/bin/startup.sh
[root@vmctl3 ~]# cat /mnt/apache-tomcat-8.0.30/webapps/ipvnat/index.html
192.168.2.200
[root@vmctl3 ~]# curl http://192.168.2.200:8080/ipvnat/index.html
192.168.2.200
[root@vmctl3 ~]# cat /mnt/apache-tomcat-8.0.30/logs/localhost_access_log.2020-06-29.txt 
192.168.2.200 - - [29/Jun/2020:19:42:44 +0800] "GET /ipvnat/index.html HTTP/1.1" 200 14

3、调度器 vmctl1 部署

确认调度器的路由转发功能是开启的(如果已开启，可以忽略)

[root@vmctl1 ~]$echo 1 > /proc/sys/net/ipv4/ip_forward
[root@vmctl1 ~]$cat /proc/sys/net/ipv4/ip_forward
1
#修改配置文件，设置永久规则
[root@vmctl1 ~]$echo "net.ipv4.ip_forward = 1" >> /etc/sysctl.conf 
[root@vmctl1 ~]$tail -1 /etc/sysctl.conf
net.ipv4.ip_forward = 1
[root@vmctl1 ~]$

#配置网卡信息
[root@vmctl1 ~]$ls /etc/sysconfig/network-scripts/
ifcfg-eth0   ifdown-ipv6      ifdown-tunnel  ifup-isdn    ifup-TeamPort
ifcfg-eth1   ifdown-isdn      ifup           ifup-plip    ifup-tunnel
ifcfg-lo     ifdown-post      ifup-aliases   ifup-plusb   ifup-wireless
ifdown       ifdown-ppp       ifup-bnep      ifup-post    init.ipv6-global
ifdown-bnep  ifdown-routes    ifup-eth       ifup-ppp     network-functions
ifdown-eth   ifdown-sit       ifup-ib        ifup-routes  network-functions-ipv6
ifdown-ib    ifdown-Team      ifup-ippp      ifup-sit
ifdown-ippp  ifdown-TeamPort  ifup-ipv6      ifup-Team

#网卡eth0
[root@vmctl1 ~]$cat  /etc/sysconfig/network-scripts/ifcfg-eth0
NAME=eth0
DEVICE=eth0
TYPE=Ethernet
IPADDR=192.168.4.5
NATMASK=255.255.255.0
ONBOOT=yes
BOOTPROTO=static

#网卡eth1
[root@vmctl1 ~]$cat  /etc/sysconfig/network-scripts/ifcfg-eth1
NAME=eth1
DEVICE=eth1
TYPE=Ethernet
IPADDR=192.168.2.5
NATMASK=255.255.255.0
ONBOOT=yes
BOOTPROTO=static

#安装ipvsadm软件包
[root@vmctl1 ~]$yum -y install ipvsadm

#创建集群服务，采用加权轮询算法 wrr
[root@vmctl1 ~]$ipvsadm -A -t 192.168.4.5:8080 -s wrr
[root@vmctl1 ~]$ipvsadm -Ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  192.168.4.5:8080 wrr
[root@vmctl1 ~]$

#添加真实服务器，参数-m代表nat模式，2，100权重是1， 2.200权重是2
[root@vmctl1 ~]$ipvsadm -a -t 192.168.4.5:8080 -r 192.168.2.100 -w 1 -m
[root@vmctl1 ~]$ipvsadm -a -t 192.168.4.5:8080 -r 192.168.2.200 -w 2 -m
[root@vmctl1 ~]$ipvsadm -Ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  192.168.4.5:8080 wrr
  -> 192.168.2.100:8080           Masq    1      0          0         
  -> 192.168.2.200:8080           Masq    2      0          0         
[root@vmctl1 ~]$

#保存永久规则
[root@vmctl1 ~]$ipvsadm-save -n > /etc/sysconfig/ipvsadm
[root@vmctl1 ~]$cat /etc/sysconfig/ipvsadm
-A -t 192.168.4.5:8080 -s wrr
-a -t 192.168.4.5:8080 -r 192.168.2.100:8080 -m -w 1
-a -t 192.168.4.5:8080 -r 192.168.2.200:8080 -m -w 2
[root@vmctl1 ~]$

4、客户端vmctl5，测试

经过测试会发现，后端真是服务器记录的调度器192.168.4.5的地址。

NAT模式下，一个请求的过程：客户端发出请求到调度器，调度器根据配置的算法，把请求分发给后端真实服务器，后端真实服务器处理后把结果返回给调度器，最后调度器再把请求返回给客户端。所以大并发访问时，调度器成为瓶颈。

[root@vmctl5 ~]# curl http://192.168.4.5:8080/ipvnat/index.html
192.168.2.100
[root@vmctl5 ~]# curl http://192.168.4.5:8080/ipvnat/index.html
192.168.2.200
[root@vmctl5 ~]# curl http://192.168.4.5:8080/ipvnat/index.html
192.168.2.200
[root@vmctl5 ~]# 
[root@vmctl5 ~]# curl http://192.168.4.5:8080/ipvnat/index.html
192.168.2.100
[root@vmctl5 ~]# curl http://192.168.4.5:8080/ipvnat/index.html
192.168.2.200
[root@vmctl5 ~]# curl http://192.168.4.5:8080/ipvnat/index.html
192.168.2.200
[root@vmctl5 ~]# 

#调度器上InActConn列显示真是服务器的访问次数
[root@vmctl1 ~]$ipvsadm -Ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  192.168.4.5:8080 wrr
  -> 192.168.2.100:8080           Masq    1      0          2         
  -> 192.168.2.200:8080           Masq    2      0          4         
[root@vmctl1 ~]$

#后端服务器1，上查看访问日志
[root@vmctl2 ~]# cat /mnt/apache-tomcat-8.0.30/logs/localhost_access_log.2020-06-29.txt 
192.168.2.100 - - [29/Jun/2020:19:42:18 -0700] "GET /ipvnat/index.html HTTP/1.1" 200 14
192.168.4.100 - - [29/Jun/2020:20:48:51 -0700] "GET /ipvnat/index.html HTTP/1.1" 200 14
192.168.4.100 - - [29/Jun/2020:20:48:56 -0700] "GET /ipvnat/index.html HTTP/1.1" 200 14
[root@vmctl2 ~]#

#后端服务器2，上查看访问日志
[root@vmctl3 ~]# cat /mnt/apache-tomcat-8.0.30/logs/localhost_access_log.2020-06-29.txt 
192.168.2.200 - - [29/Jun/2020:19:42:44 +0800] "GET /ipvnat/index.html HTTP/1.1" 200 14
192.168.4.100 - - [29/Jun/2020:20:48:52 +0800] "GET /ipvnat/index.html HTTP/1.1" 200 14
192.168.4.100 - - [29/Jun/2020:20:48:53 +0800] "GET /ipvnat/index.html HTTP/1.1" 200 14
192.168.4.100 - - [29/Jun/2020:20:48:57 +0800] "GET /ipvnat/index.html HTTP/1.1" 200 14
192.168.4.100 - - [29/Jun/2020:20:48:57 +0800] "GET /ipvnat/index.html HTTP/1.1" 200 14
[root@vmctl3 ~]#

5、部署LVS的DR模式

 IP地址主机名
客户端eth0(cip)  192.168.2.210vmctl6
调度器

eth0(dip) 192.168.2.160

eth0:0(vip) 192.168.2.150

vmctl4
真实服务器1

eth0(rip) 192.168.2.100

lo:0  192.168.2.150/32 注意掩码是32位

vmctl2
真实服务器2

eth0(rip) 192.168.2.200

lo:0 192.168.2.150/32 注意掩码是32位

vmctl3

说明：vip是对客户端提供服务的IP地址，rip是后端真实服务器的ip地址，dip是调度器和后端服务器通信的ip地址(vip必须配置在虚拟接口)

注意：为了防止冲突，vip必须配置在网卡的虚拟接口。调度器使用dip和rip通信，否则会出现192.168.2.150和192.168.2.150通信。

1、真实服务器1 vmctl2 详细操作如下，

#配置vmctl2的网络信息，记得关闭selinux和firewalld
[root@vmctl2 network-scripts]# cd /etc/sysconfig/network-scripts/
[root@vmctl2 network-scripts]# ls
ifcfg-eth0   ifdown-isdn      ifup          ifup-plip      ifup-tunnel
ifcfg-lo     ifdown-post      ifup-aliases  ifup-plusb     ifup-wireless
ifdown       ifdown-ppp       ifup-bnep     ifup-post      init.ipv6-global
ifdown-bnep  ifdown-routes    ifup-eth      ifup-ppp       network-functions
ifdown-eth   ifdown-sit       ifup-ib       ifup-routes    network-functions-ipv6
ifdown-ib    ifdown-Team      ifup-ippp     ifup-sit
ifdown-ippp  ifdown-TeamPort  ifup-ipv6     ifup-Team
ifdown-ipv6  ifdown-tunnel    ifup-isdn     ifup-TeamPort
[root@vmctl2 network-scripts]# cp ifcfg-lo{,:0}

[root@vmctl2 network-scripts]# vim ifcfg-lo:0
DEVICE=lo:0
IPADDR=192.168.2.150
NETMASK=255.255.255.255
NETWORK=192.168.2.150
BROADCAST=192.168.2.150
ONBOOT=yes
NAME=lo:0

[root@vmctl2 network-scripts]# vim ifcfg-eth0
NAME=eth0
DEVICE=eth0
TYPE=Ethernet
IPADDR=192.168.2.100
NATMASK=255.255.255.0
ONBOOT=yes
BOOTPROTO=static

注意：lo:0 也配置了和调度器的vip一样的ip地址，默认肯定会出现冲突
下面修改配置文件永久有效，主要目的就是实现访问 192.168.2.150的数据包，只有调度器会响应，其他主机不做任何响应
[root@vmctl2 network-scripts]# vim /etc/sysctl.conf
#添加如下4行内容
net.ipv4.conf.all.arp_ignore = 1
net.ipv4.conf.lo.arp_ignore = 1
net.ipv4.conf.all.arp_announce = 2
net.ipv4.conf.lo.arp_announce = 2
#当有arp广播问谁是192.168.2.150时，本机忽略该arp广播，不做任何回应
#本机不要向外宣告自己的lo回环地址是192.168.2.150

#重启网络生效
[root@vmctl2 ~]# systemctl restart network
[root@vmctl2 ~]# cat /proc/sys/net/ipv4/conf/all/arp_ignore 
1
[root@vmctl2 ~]# cat /proc/sys/net/ipv4/conf/all/arp_announce 
2

#查看网卡信息
[root@vmctl2 ~]# ifconfig 
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.2.100  netmask 255.255.255.0  broadcast 192.168.2.255
        inet6 fe80::20c:29ff:fee7:d43  prefixlen 64  scopeid 0x20<link>
        ether 00:0c:29:e7:0d:43  txqueuelen 1000  (Ethernet)
        RX packets 12655  bytes 1135581 (1.0 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 9003  bytes 956550 (934.1 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1  (Local Loopback)
        RX packets 928  bytes 74539 (72.7 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 928  bytes 74539 (72.7 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo:0: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 192.168.2.150  netmask 255.255.255.255
        loop  txqueuelen 1  (Local Loopback)

#安装tomcat就不写了
[root@vmctl2 ~]# curl http://192.168.2.100:8080/ipvnat/index.html
192.168.2.100
[root@vmctl2 ~]# tail -1 /mnt/apache-tomcat-8.0.30/logs/localhost_access_log.2020-06-29.txt 
192.168.2.100 - - [29/Jun/2020:09:23:21 -0700] "GET /ipvnat/index.html HTTP/1.1" 200 14
[root@vmctl2 ~]#

2、真实服务器2 vmctl3，详细操作如下，

[root@vmctl3 ~]# cd /etc/sysconfig/network-scripts/
[root@vmctl3 network-scripts]# ls
ifcfg-eth0   ifdown-isdn      ifdown-tunnel  ifup-isdn    ifup-Team
ifcfg-lo     ifdown-post      ifup           ifup-plip    ifup-TeamPort
ifdown       ifdown-ppp       ifup-aliases   ifup-plusb   ifup-tunnel
ifdown-bnep  ifdown-routes    ifup-bnep      ifup-post    ifup-wireless
ifdown-eth   ifdown-sit       ifup-eth       ifup-ppp     init.ipv6-global
ifdown-ippp  ifdown-Team      ifup-ippp      ifup-routes  network-functions
ifdown-ipv6  ifdown-TeamPort  ifup-ipv6      ifup-sit     network-functions-ipv6

[root@vmctl3 network-scripts]# cp ifcfg-lo{,:0}
DEVICE=lo:0
IPADDR=192.168.2.150
NETMASK=255.255.255.255
NETWORK=192.168.2.150
BROADCAST=192.168.2.150
ONBOOT=yes
NAME=lo:0

[root@vmctl3 network-scripts]# vim ifcfg-eth0 
NAME=eth0
DEVICE=eth0
TYPE=Ethernet
IPADDR=192.168.2.200
NATMASK=255.255.255.0
ONBOOT=yes
BOOTPROTO=static

[root@vmctl3 ~]# vim /etc/sysctl.conf
#添加下面的4行
net.ipv4.conf.all.arp_ignore = 1
net.ipv4.conf.lo.arp_ignore = 1
net.ipv4.conf.all.arp_announce = 2
net.ipv4.conf.lo.arp_announce = 2

#重启网络
[root@vmctl3 ~]# systemctl restart network
[root@vmctl3 ~]# cat /proc/sys/net/ipv4/conf/all/arp_ignore 
1
[root@vmctl3 ~]# cat /proc/sys/net/ipv4/conf/all/arp_announce 
2
[root@vmctl3 ~]# ifconfig 
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.2.200  netmask 255.255.255.0  broadcast 192.168.2.255
        inet6 fe80::20c:29ff:fecb:9c00  prefixlen 64  scopeid 0x20<link>
        ether 00:0c:29:cb:9c:00  txqueuelen 1000  (Ethernet)
        RX packets 11836  bytes 1482516 (1.4 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 14151  bytes 1319836 (1.2 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1  (Local Loopback)
        RX packets 57  bytes 4761 (4.6 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 57  bytes 4761 (4.6 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo:0: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 192.168.2.150  netmask 255.255.255.255
        loop  txqueuelen 1  (Local Loopback)


#安装启动tomcat，写测试页面
[root@vmctl3 ~]# curl http://192.168.2.200:8080/ipvnat/index.html
192.168.2.200
[root@vmctl3 ~]# tail -1 /mnt/apache-tomcat-8.0.30/logs/localhost_access_log.2020-06-29.txt 
192.168.2.200 - - [29/Jun/2020:09:41:39 +0800] "GET /ipvnat/index.html HTTP/1.1" 200 14
[root@vmctl3 ~]#

3、调度器vmctl4，详细操作如下，

#配置网络信息
[root@vmctl4 network-scripts]# cd /etc/sysconfig/network-scripts/
[root@vmctl4 network-scripts]# ls
ifcfg-eth0   ifdown-isdn      ifdown-tunnel  ifup-isdn    ifup-Team
ifcfg-lo     ifdown-post      ifup           ifup-plip    ifup-TeamPort
ifdown       ifdown-ppp       ifup-aliases   ifup-plusb   ifup-tunnel
ifdown-bnep  ifdown-routes    ifup-bnep      ifup-post    ifup-wireless
ifdown-eth   ifdown-sit       ifup-eth       ifup-ppp     init.ipv6-global
ifdown-ippp  ifdown-Team      ifup-ippp      ifup-routes  network-functions
ifdown-ipv6  ifdown-TeamPort  ifup-ipv6      ifup-sit     network-functions-ipv6
[root@vmctl4 network-scripts]# cp ifcfg-eth0{,:0}
[root@vmctl4 network-scripts]# vim ifcfg-eth0:0
NAME=eth0:0
DEVICE=eth0:0
TYPE=Ethernet
IPADDR=192.168.2.150
NATMASK=255.255.255.0
ONBOOT=yes
BOOTPROTO=static

#重启网络
[root@vmctl4 network-scripts]# systemctl restart network
[root@vmctl4 network-scripts]# ifconfig 
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.2.160  netmask 255.255.255.0  broadcast 192.168.2.255
        inet6 fe80::20c:29ff:fea4:3e43  prefixlen 64  scopeid 0x20<link>
        ether 00:0c:29:a4:3e:43  txqueuelen 1000  (Ethernet)
        RX packets 648  bytes 63967 (62.4 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 331  bytes 49241 (48.0 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

eth0:0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.2.150  netmask 255.255.255.0  broadcast 192.168.2.255
        ether 00:0c:29:a4:3e:43  txqueuelen 1000  (Ethernet)

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1  (Local Loopback)
        RX packets 8  bytes 528 (528.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 8  bytes 528 (528.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

#安装ipvsadm
[root@vmctl4 network-scripts]# yum -y install ipvsadm
#参数-g代表DR模式，采用wrr算法，2.100权重1，2，200权重2
[root@vmctl4 ~]# ipvsadm -A -t 192.168.2.150:8080 -s wrr
[root@vmctl4 ~]# ipvsadm -a -t 192.168.2.150:8080 -r 192.168.2.100 -g -w 1
[root@vmctl4 ~]# ipvsadm -a -t 192.168.2.150:8080 -r 192.168.2.200 -g -w 2
[root@vmctl4 ~]# ipvsadm -Ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  192.168.2.150:8080 wrr
  -> 192.168.2.100:8080           Route   1      0          0         
  -> 192.168.2.200:8080           Route   2      0          0

4、使用客户端测试

#客户端测试
[root@vmctl6 ~]# ifconfig eth0
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.2.210  netmask 255.255.255.0  broadcast 192.168.2.255
        inet6 fe80::20c:29ff:fe9b:e772  prefixlen 64  scopeid 0x20<link>
        ether 00:0c:29:9b:e7:72  txqueuelen 1000  (Ethernet)
        RX packets 240  bytes 26842 (26.2 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 84  bytes 12772 (12.4 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

[root@vmctl6 ~]# curl http://192.168.2.150:8080/ipvnat/index.html
192.168.2.200
[root@vmctl6 ~]# curl http://192.168.2.150:8080/ipvnat/index.html
192.168.2.100
[root@vmctl6 ~]# curl http://192.168.2.150:8080/ipvnat/index.html
192.168.2.200
[root@vmctl6 ~]# curl http://192.168.2.150:8080/ipvnat/index.html
192.168.2.200
[root@vmctl6 ~]# 
[root@vmctl6 ~]# curl http://192.168.2.150:8080/ipvnat/index.html
192.168.2.100
[root@vmctl6 ~]# curl http://192.168.2.150:8080/ipvnat/index.html
192.168.2.200
[root@vmctl6 ~]# curl http://192.168.2.150:8080/ipvnat/index.html
192.168.2.200
[root@vmctl6 ~]# 

#调度器查看规则表，InActConn列，显示访问次数
[root@vmctl4 ~]# ipvsadm -Ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  192.168.2.150:8080 wrr
  -> 192.168.2.100:8080           Route   1      0          2         
  -> 192.168.2.200:8080           Route   2      0          5         
[root@vmctl4 ~]#

#真实服务器行查看访问记录日志，记录的是客户端的IP，不是调度器的IP
[root@vmctl2 ~]# cat /mnt/apache-tomcat-8.0.30/logs/localhost_access_log.2020-06-29.txt 
192.168.2.100 - - [29/Jun/2020:09:23:21 -0700] "GET /ipvnat/index.html HTTP/1.1" 200 14
192.168.2.210 - - [29/Jun/2020:09:51:42 -0700] "GET /ipvnat/index.html HTTP/1.1" 200 14
192.168.2.210 - - [29/Jun/2020:09:51:54 -0700] "GET /ipvnat/index.html HTTP/1.1" 200 14
[root@vmctl2 ~]#

[root@vmctl3 ~]# cat /mnt/apache-tomcat-8.0.30/logs/localhost_access_log.2020-06-29.txt
192.168.2.200 - - [29/Jun/2020:09:41:39 +0800] "GET /ipvnat/index.html HTTP/1.1" 200 14
192.168.2.210 - - [29/Jun/2020:09:51:35 +0800] "GET /ipvnat/index.html HTTP/1.1" 200 14
192.168.2.210 - - [29/Jun/2020:09:51:38 +0800] "GET /ipvnat/index.html HTTP/1.1" 200 14
192.168.2.210 - - [29/Jun/2020:09:51:40 +0800] "GET /ipvnat/index.html HTTP/1.1" 200 14
192.168.2.210 - - [29/Jun/2020:09:51:51 +0800] "GET /ipvnat/index.html HTTP/1.1" 200 14
192.168.2.210 - - [29/Jun/2020:09:51:52 +0800] "GET /ipvnat/index.html HTTP/1.1" 200 14
[root@vmctl3 ~]#

DR模式，一个请求过程：客户端发出请求到调度器，调度器根据算法把请求分发给后端真实服务器，后端真实服务器处理完成后，直接把处理结果返回客户端，调度器只分发请求不做回应。

NAT模式，后端真实服务器记录的是调度器的地址，DR模式，后端真实服务器记录的是客户端的地址，LVS最常用DR模式。

------------------------------------------------------------------------------------------------------------------------------------------------------

扩展知识：默认LVS不带健康检查功能，需要自己写动态监测脚本(参考脚本如下，仅供参考)

[root@vmctl4 ~]#vim check.sh
#!/bin/bash
VIP=192.168.2.150
RIP1=192.168.2.100
RIP2=192.168.2.200
while:
do
    for IP in $RIP1 $RIP2
    do
        curl -s http://$IP:8080/ipvnat/index.html &>/dev/null
        web_status=$?
        ipvsadm -Ln | grep -q $IP
        web_in_lvs=$?
        if [ #web_status -ne 0 -a $web_in_lvs -eq 0 ];then
            ipvsadm -d -t $VIP -r $IP #web服务挂了，删除这条规则
        elif [ $web_status -eq 0 -a $web_in_lvs -ne 0 ];then
            ipvsadm -a -t $VIP -r $IP #web服务正常，没有这条规则，就添加
        fi
    done
    sleep 1
done

 

版权声明：本文为CSDN_xt_peng原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接和本声明。