Managing Serviceguard Sixteenth Edition, March 2009

IP addresses are configured only on each primary network interface card; standby
cards are not configured with an IP address. Multiple IPv4 addresses on the same
network card must belong to the same IP subnet.
CAUTION: HP strongly recommends that you add relocatable addresses to packages
only by editing ip_address (page 273) in the package configuration file (or IP [] entries in
the control script of a legacy package) and running cmapplyconf (1m).
Load Sharing
Serviceguard allows you to configure several services into a single package, sharing a
single IP address; in that case all those services will fail over when the package does.
If you want to be able to load-balance services (that is, move a specific service to a less
loaded system when necessary) you can do so by putting each service in its own package
and giving it a unique IP address.
Monitoring LAN Interfaces and Detecting Failure: Link Level
At regular intervals, Serviceguard polls all the network interface cards specified in the
cluster configuration file. Network failures are detected within each single node in the
following manner. One interface on the node is assigned to be the poller. The poller
will poll the other primary and standby interfaces in the same bridged net on that node
to see whether they are still healthy. Normally, the poller is a standby interface; if there
are no standby interfaces in a bridged net, the primary interface is assigned the polling
task. (Bridged nets are explained in “Redundant Network Components ” (page 38) in
Chapter 2.)
The polling interface sends LAN packets to all other interfaces in the node that are on
the same bridged net and receives packets back from them.
Whenever a LAN driver reports an error, Serviceguard immediately declares that the
card is bad and performs a local switch, if applicable. For example, when the card fails
to send, Serviceguard will immediately receive an error notification and it will mark
the card as down.
Serviceguard Network Manager also looks at the numerical counts of packets sent and
received on an interface to determine if a card is having a problem. There are two ways
Serviceguard can handle the counts of packets sent and received. In the cluster
configuration file, choose one of the following values for the
NETWORK_FAILURE_DETECTION parameter:
NOTE: For a full discussion, see the white paper Serviceguard Network Manager: Inbound
Failure Detection Enhancement at http://docs.hp.com -> High Availability
-> Serviceguard -> White Papers.
• INOUT: When both the inbound and outbound counts stop incrementing for a
certain amount of time, Serviceguard will declare the card as bad. (Serviceguard
How the Network Manager Works 93