Installation guide

they contain the real IP of the server instead. The only node that should respond to ARP

requests for any of the VIPs is the current active LVS node.

2. Once this has been completed on each real server, save the ARP table entries by typing the

following commands on each real server:

service arptables_jf save

chkconfig --level 2345 arptables_jf on

The chkconfig command will cause the system to reload the arptables configuration on

bootup — before the network is started.

3. Configure the virtual IP address on all real servers using ifconfig to create an IP alias. For

example:

# ifconfig eth0:1 192.168.76.24 netmask 255.255.252.0 broadcast

192.168.79.255 up

Or using the iproute2 utility ip, for example:

# ip addr add 192.168.76.24 dev eth0

As previously noted, the virtual IP addresses can not be configured to start on boot using the

Red Hat system configuration tools. One way to work around this issue is to place these

commands in /etc/rc.d/rc.local.

4. Configure Piranha for Direct Routing. Refer to Chapter 4, Configuring the LVS Routers with

Piranha Configuration Tool for more information.

2.2. Direct Routing and iptables

You may also work around the ARP issue using the direct routing method by creating iptables

firewall rules. To configure direct routing using iptables, you must add rules that create a

transparent proxy so that a real server will service packets sent to the VIP address, even though

the VIP address does not exist on the system.

The iptables method is simpler to configure than the arptables_jf method. This method also

circumvents the LVS ARP issue entirely, because the virtual IP address(es) only exist on the

active LVS director.

However, there are performance issues using the iptables method compared to

arptables_jf, as there is overhead in forwarding/masquerading every packet.

You also cannot reuse ports using the iptables method. For example, it is not possible to run

Chapter 3. Setting Up LVS