Red Hat Cluster Suite, Manual

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Chapter 9. Setting Up a Red Hat Enterprise Linux LVS Cluster 105
Important
Be sure each interface on the backup node services the same network as the interface on
primary node. For instance, if eth0 connects to the public network on the primary node, it
must also connect to the public network on the backup node as well.
9.1.2. Routing on the Real Servers
The most important thing to remember when configuring the real servers network inter-
faces in a NAT cluster is to set the gateway for the NAT floating IP address of the LVS
router. In this example, that address will be 10.11.12.10.
Note
Once the network interfaces are up on the real servers, the machines will be unable to
ping or connect in other ways to the public network. This is normal. You will, however, be
able to ping the real IP for the LVS router’s private interface, in this case 10.11.12.8.
So the real server’s
/etc/sysconfig/network-scripts/ifcfg-eth0
file could look
similar to this:
DEVICE=eth0
ONBOOT=yes
BOOTPROTO=static
IPADDR=10.11.12.1
NETMASK=255.255.255.0
GATEWAY=10.11.12.10
Warning
If a real server has more than one network interface configured with a
GATEWAY=
line, the
first one to come up will get the gateway. Therefore if both
eth0
and
eth1
are configured
and
eth1
is used for LVS clustering, the real servers may not route requests properly.
It is best to turn off extraneous network interfaces by setting
ONBOOT=
no in their network
scripts within the
/etc/sysconfig/network-scripts/
directory or by making sure the
gateway is correctly set in the interface which comes up first.