Managing HP Serviceguard for Linux Ninth Edition, April 2009

Figure 3-20 Bonded NICs Configured for Load Balancing
Monitoring LAN Interfaces and Detecting Failure: Link Level
At regular intervals, determined by the NETWORK_POLLING_INTERVAL (see “Cluster
Configuration Parameters ” (page 100)), Serviceguard polls all the network interface
cards specified in the cluster configuration file (both bonded and non-bonded). If the
link status of an interface is down, Serviceguard marks the interface, and all subnets
running on it, as down; this is shown in the output of cmviewcl (1m); see “Reporting
Link-Level and IP-Level Failures” (page 82). When the link comes back up, Serviceguard
marks the interface, and all subnets running on it, as up.
Monitoring LAN Interfaces and Detecting Failure: IP Level
Serviceguard can also monitor the IP level, checking Layer 3 health and connectivity
for both IPv4 and IPv6 subnets. This is done by the IP Monitor, which is configurable:
you can enable IP monitoring for any subnet configured into the cluster, but you do
not have to monitor any. You can configure IP monitoring for a subnet, or turn off
monitoring, while the cluster is running.
The IP Monitor:
• Detects when a network interface fails to send or receive IP messages, even though
it is still up at the link level.
• Handles the failure, failover, recovery, and failback.
78 Understanding Serviceguard Software Components