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NOTE: CentOS Enterprise Linux is built from the Red Hat Enterprise Linux source code. Other than logo and name changes CentOS Enterprise Linux is compatible with the equivalent Red Hat version. This document applies equally to both Red Hat and CentOS Enterprise Linux.

9.2. Putting the Cluster Together

After determining which of the above routing methods to use, the hardware for the LVS cluster should be linked together on the network.

Important Important

The adapter devices on the LVS routers must be configured to access the same networks. For instance if eth0 connects to public network and eth1 connects to the private network, then these same devices on the backup LVS router must connect to the same networks.

Also the gateway listed in the first interface to come up at boot time is added to the routing table and subsequent gateways listed in other interfaces are ignored. This is especially important to consider when configuring the real servers.

After physically connecting together the cluster hardware, configure the network interfaces on the primary and backup LVS routers. This can be done using a graphical application such as system-config-network or by editing the network scripts manually. For more information about adding devices using system-config-network, see the chapter titled Network Configuration in the Red Hat Enterprise Linux System Administration Guide. For more information on editing network scripts by hand, see the chapter titled Network Scripts in the Red Hat Enterprise Linux Reference Guide. For the remainder of the chapter, example alterations to network interfaces are made either manually or through the Piranha Configuration Tool.

9.2.1. General LVS Networking Tips

Configure the real IP addresses for both the public and private networks on the LVS routers before attempting to configure the cluster using the Piranha Configuration Tool. The sections on each topography give example network addresses, but the actual network addresses are needed. Below are some useful commands for bringing up network interfaces or checking their status.

Bringing Up Real Network Interfaces

The best way to bring up any real network interface is to use the following commands as root replacing N with the number corresponding to the interface (eth0 and eth1):

/sbin/ifup ethN
Warning Warning

Do not use the ifup scripts to bring up any floating IP addresses you may configure using Piranha Configuration Tool (eth0:1 or eth1:1). Use the service command to start pulse instead (see Section 10.8 Starting the Cluster for details).

To bring a network interface down, type the following command:

/sbin/ifdown ethN

Again, replace N in the above command with the number corresponding to the interface you wish to bring down.

Checking the Status of Network Interfaces

If you need to check which network interfaces are up at any given time, type the following:


To view the routing table for a machine, issue the following command:


  Published under the terms of the GNU General Public License Design by Interspire