Managing HP Serviceguard for Linux Ninth Edition, April 2009

NOTE: This is not the default. If cmquerycl does not detect a gateway for the subnet
in question, it sets IP_MONITOR to OFF, disabling IP-level polling for this subnet; if it
does detect a gateway, it populates POLLING_TARGET, enabling target polling. See
SUBNET under “Cluster Configuration Parameters ” (page 100) for more information.
The IP Monitor section of the cluster configuration file will look similar to the following
in the case of a subnet on which IP monitoring is disabled:
SUBNET 192.168.3.0
IP_MONITOR OFF
NOTE: This is the default if cmquerycl does not detect a gateway for the subnet in
question; it is equivalent to having no SUBNET entry for the subnet. See SUBNET under
“Cluster Configuration Parameters ” (page 100) for more information.
Failure and Recovery Detection Times
With the default NETWORK_POLLING_INTERVAL of 2 seconds (see “Cluster
Configuration Parameters ” (page 100)), the IP monitor will detect IP failures typically
within 8–10 seconds for Ethernet and within 16–18 seconds for InfiniBand. Similarly,
with the default NETWORK_POLLING_INTERVAL, the IP monitor will detect the
recovery of an IP address typically within 8–10 seconds for Ethernet and with 16–18
seconds for InfiniBand.
IMPORTANT: HP strongly recommends that you do not to change the default
NETWORK_POLLING_INTERVAL value of 2 seconds.
See also “Reporting Link-Level and IP-Level Failures” (page 82).
Constraints and Limitations
• A subnet must be configured into the cluster in order to be monitored.
• Polling targets are not detected beyond the first-level router.
• Polling targets must accept and respond to ICMP (or ICMPv6) ECHO messages.
• A peer IP on the same subnet should not be a polling target because a node can
always ping itself.
The following constraints apply to peer polling when there are only two interfaces on
a subnet:
• If one interface fails, both interfaces and the entire subnet will be marked down
on each node, unless bonding is configured and there is a working standby.
• If the node that has one of the interfaces goes down, the subnet on the other node
will be marked down.
How the Network Manager Works 81