View source for Building Two-Node Directors/Real Servers using LVS and Keepalived

== Introduction ==
This guide is a brief explanation on getting a two node director/[[real server]] setup going using [[LVS]] and [[keepalived]].

This is an adaptation of the information at [http://www.ultramonkey.org/2.0.1/topologies/sl-ha-lb-eg.html Ultra Monkey: Streamline High Availablility and Load Balancing] to work with [[keepalived]].

It is primarily targeted at RHEL3/4 (RedHat Enterprise Linux).

== Goals ==
Setup a two node [[LVS]] cluster with Apache as the virtualised services, with both nodes operating as both directors and [[real server]]s.<br>
Setup healthchecking of services (httpd).<br>
Setup lvs-syncing of connections (ipvsadm sync daemon).<br>

== Knowledge Required ==

Understanding of Layer 3 [[load balancing]].<br>
Understanding of Linux LVS.<br>
Understanding of Apache configuration.<br>

== Components Required ==

Base installation of RHEL3/4.<br>
RPM Packages for httpd.<br>
RPM Packages for [[keepalived]].<br>
RPM Packages for [[ipvsadm]].<br>

== Instructions ==
Install keepalived and IPVSADM on both servers.

On the first server create the file /etc/keepalived/keepalived.conf :

 global_defs {
   router_id DEV 
 }
 vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 51
    priority 100
    advert_int 10
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
       192.168.6.240
   }
 }
 virtual_server 192.168.6.240 80 {
    delay_loop 10
    lb_algo rr
    lb_kind DR
    persistence_timeout 5
    protocol TCP
    real_server 192.168.6.4 80 {
        TCP_CHECK {
        }
    }
    real_server 192.168.6.5 80 {
        TCP_CHECK {
        }
    }
  }
 }

On the second server create the file /etc/keepalived/keepalived.conf :
 global_defs {
   router_id DEV
 }
 vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    virtual_router_id 51
    priority 99
    advert_int 10
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
       192.168.6.240
    }
 }
 virtual_server 192.168.6.240 80 {
    delay_loop 10
    lb_algo rr
    lb_kind DR
    persistence_timeout 5
    protocol TCP
    real_server 192.168.6.5 80 {
        TCP_CHECK {
        }
    }
 }

On both servers create the file /etc/sysconfig/network-scripts/ifcfg-lo:0
 DEVICE=lo:0
 IPADDR=192.168.6.240
 NETMASK=255.255.255.255
 ONBOOT=yes
 NAME=loopback

In order to avoid warning messages, we explicitly say that our gateway is on eth0.
Add in /etc/sysconfig/network
 GATEWAYDEV=eth0

Add in /etc/sysctl.conf :
 net.ipv4.conf.eth0.arp_ignore = 1
 net.ipv4.conf.eth0.arp_announce = 2
 # Enables packet forwarding
 net.ipv4.ip_forward = 1

 ifup lo
 sysctl -p

== Architecture ==
[[Image:sl-ha-lb-eg.jpg|center]]


{{lvs-example-stub}}


[[Category:LVS Examples|Keepalived]]