HP Serviceguard A.11.20- Managing Serviceguard Twentieth Edition, August 2011

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” (page 309).)
• 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,
and failing over across subnets can take longer.
List the nodes in order of preference rather than using the wildcard.
• You should configure IP monitoring for each subnet; see “Monitoring LAN Interfaces and
Detecting Failure: IP Level” (page 73).
Restrictions
The following restrictions apply:
• All nodes in the cluster must belong to the same network domain (that is, the domain portion
of the fully-qualified domain name must be the same).
• The nodes must be fully connected at the IP level.
• A minimum of two heartbeat paths must be configured for each cluster node.
• There must be less than 200 milliseconds of latency in the heartbeat network.
• Each heartbeat subnet on each node must be physically routed separately to the heartbeat
subnet on another node; that is, each heartbeat path must be physically separate:
◦ The heartbeats must be statically routed; static route entries must be configured on each
node to route the heartbeats through different paths.
◦ Failure of a single router must not affect both heartbeats at the same time.
• IPv6 heartbeat subnets are not supported in a cross-subnet configuration.
• IPv6–only and mixed modes are not supported in a cross-subnet configuration. For more
information about these modes, see “About Hostname Address Families: IPv4-Only, IPv6-Only,
and Mixed Mode” (page 106).
30 Understanding Serviceguard Hardware Configurations