Managing Serviceguard 11th Edition, Version A.11.16, Second Printing June 2004

Understanding Serviceguard Software Components
How the Network Manager Works
Chapter 396
How the Network Manager Works
The purpose of the network manager is to detect and recover from
network card and cable failures so that network services remain highly
available to clients. In practice, this means assigning IP addresses for
each package to the primary LAN interface card on the node where the
package is running and monitoring the health of all interfaces, switching
them when necessary.
Stationary and Relocatable IP Addresses
Each node (host system) should have at least one IP address for each
active network interface. This address, known as a stationary IP
address, is configured in the node's /etc/rc.config.d/netconf file or
in the node’s /etc/rc.config.d/netconf-ipv6 file. A stationary IP
address is not transferable to another node, but may be transferable to a
standby LAN interface card. The stationary IP address is not associated
with packages. Stationary IP addresses are used to transmit heartbeat
messages (described earlier in the section “How the Cluster Manager
Works”) and other data.
In addition to the stationary IP address, you normally assign one or more
unique IP addresses to each 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. You
can use up to 200 relocatable IP addresses in a cluster, spread over as
many as 150 packages. This can be a combination of IPv4 and IPv6
addresses.
A relocatable IP address is like a virtual host IP address that is assigned
to a package. It is recommended that you configure names for each
package through DNS (Domain Name System). A program then can 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 and relocatable IP addresses will switch to a standby
LAN interface in the event of a LAN card failure. In addition, relocatable
addresses (but not stationary addresses) can be taken over by an