The heartbeat program allows two machines to share a high availability address. Each machine has its own normal IP address used to administer the machine. There is then a third "service" IP address that SIP clients connect to. This normally runs on the primary machine as an IP alias eth0:0. The backup machine then monitors the health of the primary machine, and if it crashes the backup takes over the service IP address, again as eth0:0. The backup monitors the primary through the network and optionally through a null modem cable connected between the COM1 serial ports on each machine.

To configure heartbeat

Do the steps below on both machines. First, install the packages:

Debian / Ubuntu:

  • apt-get install heartbeat

Redhat Enterprise:

The heartbeat packages must be installed from CD.

Others:

  • yum -y install heartbeat
  • chkconfig heartbeat on

Then:

  • cd /etc/ha.d
  • cp /opt/enswitch/current/install/etc/ha.d/* /etc/ha.d
  • chmod 600 authkeys
  • vi authkeys ha.cf haresources
  • /etc/init.d/heartbeat start; tail -F /var/log/heartbeat.log &

When editing the configuration files, set the following:

  • The sha1 password in auth keys. The actual value can be anything, but must be the same on both machines and should be hard to guess. Random characters is a good option.
  • The udpport in ha.cf. This should not the same as any other heartbeat pairs (such as MySQL) on the same network. A suggested port is 696.
  • The other machine's IP address in ha.cf.
  • The gateway IP address in ha.cf.
  • The hostnames of both machines in the "node" lines. These must be exactly the same as the output of the "hostname" command on each machine.
  • If you are unable to connect a null modem cable between the machines, perhaps because they have no serial ports, remove the "baud" and "serial" lines.
  • Check that /usr/lib/heartbeat/ipfail exists. If using a 64 bit machine, it may be /usr/lib64/heartbeat/ipfail instead; if so adjust the respawn line.
  • The service IP address in haresources.
  • Check that /etc/ha.d/resource.d/opensips and /etc/ha.d/resource.d/enswitch_sipd both exist as symlinks. If not, run "/opt/enswitch/current/bin/enswitch_install opensips-ha" again.

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