Managing Serviceguard A.11.20, March 2013

IMPORTANT: Every subnet configured as a monitored_subnet in a package configuration
file must be configured into the cluster via NETWORK_INTERFACE and either STATIONARY_IP
or HEARTBEAT_IP in the cluster configuration file. See “Cluster Configuration Parameters ”
(page 114) and “Package Parameter Explanations” (page 237) for more information.
In addition to the stationary IP address, you normally assign one or more unique IP addresses to
each failover package. The package IP address is assigned to the primary LAN interface card by
the cmmodnet command in the package control script when the package starts up.
The IP addresses associated with a package are called relocatable IP addresses (also known as
package IP addresses or floating IP addresses) because the addresses can actually move from
one cluster node to another on the same subnet. You can use up to 200 relocatable IP addresses
in a cluster. These addresses can be IPv4, IPv6, or a combination of both address families.
Because system multi-node and multi-node packages do not fail over, they do not have relocatable
IP address.
A relocatable IP address is like a virtual host IP address that is assigned to a package. HP
recommends that you configure names for each package through DNS (Domain Name Service).
A program can then use the package’s name like a host name as the input to gethostbyname,
which will return the package's relocatable IP address.
Both stationary IP addresses, and relocatable IP addresses on subnets that are configured into the
cluster, will switch to a standby LAN interface in the event of a NIC failure.
In addition, relocatable addresses (but not stationary addresses) can be taken over by an adoptive
node on the same subnet if control of the package is transferred. This means that applications can
access the package via its relocatable address without knowing which node the package currently
resides on.
IMPORTANT: Any subnet that is used by a package for relocatable addresses should be
configured into the cluster via NETWORK_INTERFACE and either STATIONARY_IP or
HEARTBEAT_IP in the cluster configuration file. For more information about those parameters,
see “Cluster Configuration Parameters ” (page 114). For more information about configuring
relocatable addresses, see the descriptions of the package ip_ parameters (page 246).
NOTE: It is possible to configure a cluster that spans subnets joined by a router, with some nodes
using one subnet and some another. This is called a cross-subnet configuration. In this context, you
can configure packages to fail over from a node on one subnet to a node on another, and you
will need to configure a relocatable address for each subnet the package is configured to start on;
see “About Cross-Subnet Failover” (page 160), and in particular the subsection “Implications for
Application Deployment” (page 161).
Types of IP Addresses
Both IPv4 and IPv6 address types are supported in Serviceguard. IPv4 addresses are the traditional
addresses of the form n.n.n.n where n is a decimal digit between 0 and 255. IPv6 addresses
have the form x:x:x:x:x:x:x:x where x is the hexadecimal value of each of eight 16-bit pieces
of the 128-bit address. You can define heartbeat IPs, stationary IPs, and relocatable (package) IPs
as IPv4 or IPv6 addresses (or certain combinations of both).
Adding and Deleting Relocatable IP Addresses
When a package is started, a relocatable IP address can be added to a specified IP subnet. When
the package is stopped, the relocatable IP address is deleted from the specified subnet. These
functions are performed by the cmmodnet command in the package master control script (package
control script for legacy packages).
How the Network Manager Works 69