Using Serviceguard Extension for RAC, 6th Edition, April 2008

Figure 2-2 SG-HB/RAC-IC Traffic Separation
Each primary and standby pair protects against a single failure. With the SG-HB on
more than one subnet, a single subnet failure will not trigger a Serviceguard
reconfiguration. If the subnet with CSS-HB fails, unless subnet monitoring is used, CSS
will resolve the interconnect subnet failure with a CSS cluster reconfiguration. It will
wait for the CSS misscount time interval before handling the CSS-HB subnet failure
(by bringing down the node on which the CSS-HB subnet has failed).
The default value of CSS misscount in SGeRAC configurations is 600 seconds.
As shown in Figure 2-2, CLUSTER_INTERCONNECT_SUBNET can be used in conjunction
with the NODE_FAIL_FAST_ENABLED package configuration parameter to monitor
the CSS-HB network. A failure of CSS-HB subnet on a node should be handled by
bringing down that node. Therefore, set NODE_FAIL_FAST_ENABLED to YES for the
package monitoring the CSS-HB subnet. When Oracle Clusterware is configured as a
multi-node package and CLUSTER_INTERCONNECT_SUBNET is used to monitor the
CSS-HB subnet, if the monitored subnet fails, the failure of the CSS-HB subnet on a
node will bring down the instance of the multi-node package and the node where the
subnet has failed.
A failure of CSS-HB subnet on all nodes will result in the multi-node package failing
on the nodes one by one (resulting in that node going down), and one instance of the
multi-node package and node will remain providing services to the clients.
Use a separate package to monitor only the CSS-HB subnet and have Oracle Clusterware
multi-node package depend on the package monitoring the CSS-HB subnet. The
Cluster Communication Network Monitoring 49