Managing Serviceguard Fifteenth Edition, reprinted May 2008

Understanding Serviceguard Hardware Configurations
Redundant Network Components
Chapter 2 41
NOTE You should verify that network traffic is not too heavy on the heartbeat/
data LAN. If traffic is too heavy, this LAN might not perform adequately
in transmitting heartbeats if the dedicated heartbeat LAN fails.
Cross-Subnet Configurations
As of Serviceguard A.11.18 it is possible to configure multiple subnets,
joined by a router, both for the cluster heartbeat and for data, with some
nodes using one subnet and some another.
A cross-subnet configuration allows:
• Automatic package failover from a node on one subnet to a node on
another
• A cluster heartbeat that spans subnets.
Configuration Tasks
Cluster and package configuration tasks are affected as follows:
• You must use the -w full option to cmquerycl to discover actual or
potential nodes and subnets across routers.
• You must configure two new parameters in the package
configuration file to allow packages to fail over across subnets:
— ip_subnet_node - to indicate which nodes the subnet is
configured on
— monitored_subnet_access - to indicate whether the subnet is
configured on all nodes (FULL) or only some (PARTIAL)
(For legacy packages, see “Configuring Cross-Subnet Failover” on
page 390.)
• You should not use the wildcard (*) for node_name in the package
configuration file, as this could allow the package to fail over across
subnets when a node on the same subnet is eligible. Instead, list the
nodes in order of preference.