Managing Serviceguard Eighteenth Edition, September 2010

ip_subnet
Specifies an IP subnet used by the package for relocatable addresses; see also ip_address
(page 299) and “Stationary and Relocatable IP Addresses ” (page 90). Replaces SUBNET,
which is still supported in the package control script for legacy packages.
CAUTION: HP recommends that this subnet be configured into the cluster. You do
this in the cluster configuration file by specifying a HEARTBEAT_IP or STATIONARY_IP
under a NETWORK_INTERFACE on the same subnet, for each node in this package's
NODE_NAME list. For example, an entry such as the following in the cluster
configuration file configures subnet 192.10.25.0 (lan1) on node ftsys9:
NODE_NAME ftsys9
NETWORK_INTERFACE lan1
HEARTBEAT_IP 192.10.25.18
See “Cluster Configuration Parameters ” (page 143) for more information.
If the subnet is not configured into the cluster, Serviceguard cannot manage or monitor
it, and in fact cannot guarantee that it is available on all nodes in the package's node-name
list (page 289) . Such a subnet is referred to as an external subnet, and relocatable
addresses on that subnet are known as external addresses. If you use an external subnet,
you risk the following consequences:
• A failed interface on this subnet will not fail over to a local standby. See “Local
Switching ” (page 93) for more information about this type of failover.
• If the subnet fails, the package will not fail over to an alternate node.
• Even if the subnet remains intact, if the package needs to fail over because of some
other type of failure, it could fail to start on an adoptive node because the subnet
is not available on that node.
For these reasons, configure all ip_subnets into the cluster, unless you are using a
networking technology, such as HyperFabric, that does not support DLPI. In such
cases, follow instructions in the networking product's documentation to integrate the
product with Serviceguard.
For each subnet used, specify the subnet address on one line and, on the following
lines, the relocatable IP addresses that the package uses on that subnet. These will be
configured when the package starts and unconfigured when it halts.
For example, if this package uses subnet 192.10.25.0 and the relocatable IP addresses
192.10.25.12 and 192.10.25.13, enter:
ip_subnet 192.10.25.0
ip_address 192.10.25.12
ip_address 192.10.25.13
If you want the subnet to be monitored, specify it in the monitored_subnet parameter as
well.
298 Configuring Packages and Their Services