Construction of LVS DR Model

Dead work

• Three machines
  Distributor, also known as dispatcher (abbreviated as dir)
  The gateway of the previous rs machine needs to be changed back
  85.132
  rs1
  85.129
  rs2
  85.128
  vip
  85.200

DR Model Building

• Write the script vim/usr/local/sbin/lvs_dr.sh on dir
  The contents are as follows

#! /bin/bash
echo 1 > /proc/sys/net/ipv4/ip_forward
ipv=/usr/sbin/ipvsadm
vip=192.168.85.200
rs1=192.168.85.129
rs2=192.168.85.128
#Notice the name of the network card here.
ifdown ens37 #Intranet NIC
ifup ens37
ifconfig ens37:2 $vip broadcast $vip netmask 255.255.255.255 up
route add -host $vip dev ens37:2
$ipv -C
$ipv -A -t $vip:80 -s wrr
$ipv -a -t $vip:80 -r $rs1:80 -g -w 1
$ipv -a -t $vip:80 -r $rs2:80 -g -w 1

• The script vim/usr/local/sbin/lvs_rs.sh is also written on both rs.
  The contents are as follows

#/bin/bash
vip=192.168.85.200
#The purpose of binding vip to lo is to implement rs to return the result directly to the client
ifconfig lo:0 $vip broadcast $vip netmask 255.255.255.255 up
route add -host $vip lo:0
#The following is to change the arp kernel parameters in order to enable rs to smoothly send mac addresses to the client
#Reference document www.cnblogs.com/lgfeng/archive/2012/10/16/2726308.html
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

Execute these scripts on dir and two rs respectively

• The intranet card ens37 on dir binds VIP 192.168.85.200, and lo on rs binds VIP.
  
  Visiting VIP through browser can play the same role of load balancing as NAT mode.

keepalived lvs

• The complete architecture requires two servers (role dir) to install keepalived software separately in order to achieve high availability, but keepalived itself also has the function of load balancing, so only one keepalived software can be installed in this experiment.
  keepalived has built-in ipvsadm functionality, so there is no need to install the ipvsadm package, nor to write and execute the lvs_dir script
  The three machines are:
  dir (installation keepalived) 85.132
  rs1 85.129
  rs2 85.128
  vip 85.200

• Edit the keepalived configuration file vim/etc/keepalived/keepalived.conf
  content

vrrp_instance VI_1 {
    #BACKUP on the standby server
    state MASTER
    #The network card bound to vip is ens37
    interface ens37
    virtual_router_id 51
    #90 on standby server
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass aminglinux
    }
    virtual_ipaddress { #Address of VIP
        192.168.85.200
    }
}
virtual_server 192.168.85.200 80 { #Address of VIP
    #(Query realserver status every 10 seconds)
    delay_loop 10  
    #(lvs algorithm)
    lb_algo wlc
    #(DR mode)
    lb_kind DR
    #(The same IP connection is assigned to the same RealServer within 60 seconds)
    persistence_timeout 60
    #(Check realserver status with TCP protocol)
    protocol TCP
    real_server 192.168.85.129 80 { #IP of rs
        #(weight)
        weight 100
        TCP_CHECK {
        #(10 seconds no response timeout)
        connect_timeout 10
        nb_get_retry 3
        delay_before_retry 3
        connect_port 80
        }
    }
    real_server 192.168.85.128 80 { #IP of rs
        weight 100
        TCP_CHECK {
        connect_timeout 10
        nb_get_retry 3
        delay_before_retry 3
        connect_port 80
        }
     }
}

• Execute ipvsadm-C to clear previous ipvsadm rules

• System CTL restart network can empty the previous vip

• On both rs, the / usr/local/sbin/lvs_rs.sh script still needs to be executed

• The dir does not need to execute scripts, but it needs to execute the command of forwarding routing:
  echo 1 > /proc/sys/net/ipv4/ip_forward

• Keeping alived has a better function that can stop forwarding requests when an rs downtime occurs.
  test
  Start keepalived on dir, system CTL start keepalived
  Ipvsadm-ln checks which rs are connected and if any Nginx is turned off, it will be rejected
  

extend
haproxy+keepalived http://blog.csdn.net/xrt95050/article/details/40926255
Comparison of nginx, lvs and haproxy http://www.csdn.net/article/2014-07-24/2820837
Custom script vrrp_script in keepalived http://my.oschina.net/hncscwc/blog/158746
Implementation of lvs dr mode using only one public network ip http://storysky.blog.51cto.com/628458/338726