Managing Serviceguard Eighteenth Edition, September 2010

Figure 3-18 Local Switching After Cable Failure
Local network switching will work with a cluster containing one or more nodes. You
may wish to design a single-node cluster in order to take advantage of this local network
switching feature in situations where you need only one node and do not wish to set
up a more complex cluster.
Switching Back to Primary LAN Interfaces after Local Switching
If a primary interface fails, the IP address will be switched to a standby. You can use
the NETWORK_AUTO_FAILBACK parameter in the cluster configuration file to
configure what Serviceguard does if the primary interface is later restored.
• Default behavior: NETWORK_AUTO_FAILBACK = YES. Serviceguard will detect
and log the recovery of the interface, and will switch the IP address back to its
primary interface.
In addition, when a node is halted, the cluster daemon (cmcld) will attempt to
switch any Serviceguard-configured IP addresses on standby interfaces back to
their primary interfaces, regardless of the link state of the primary interfaces. The
intent of this switchback is to preserve the original network configuration as it
was before the cluster started. Switching back occurs on the specified node if a
96 Understanding Serviceguard Software Components