5.2. Tunneling Cluster Nodes

The tunnel forwarding method can be used only with cluster nodes running a UNIX or Linux operating system. The kernel on the node will need to be configured with IP-IP tunneling. On a Linux kernel using modules, the module may need to be loaded, using the command:

# modprobe ipip

Once the IP-IP support has been enabled, you can bring up the IP-IP tunnel interface, which is named tunl0. Simply use the ifconfig command, specifying the virtual IP address of the cluster:

# ifconfig tunl0 10.0.0.99 netmask 255.255.255.255 up

Either add the -arp option if it works, or write to the hidden files in /proc:

# echo 1 > /proc/sys/net/ipv4/conf/all/hidden

# echo 1 > /proc/sys/net/ipv4/conf/tunl0/hidden

Once this tunnel interface is set up and the ATM is configured to forward traffic to the node using the tunneling method, the cluster node is ready to go.

There is no need to load ipip module manually on the ATM that is also configured as a service node.

Keeping ARP replies turned off on the service node's loopback interface is recommended even after service nodes are restarted. For example, you may want to put these lines into /etc/rc.d/rc.local script to make it effective every time after system is booted. You may also use turbonetcfg tool to configure your alias.