Technical Considerations for a Serviceguard Cluster that Spans Multiple IP Subnets, July 2009
11
Incorrect configuration of heartbeat routing
The following excerpts from the HP-UX file /etc/rc.config.d/netconf on Node A and Node C
show a routing configuration that does not meet the requirement for separately routed heartbeat
subnets. In these excerpts, green text indicates correct routing entries whereas red text indicates an
incorrect routing gateway.
Table 2 – Configuration file showing incorrect heartbeat routing
Configuration file: /etc/rc.config.d/netconf
Node A Node C
IP_ADDRESS[0]=5.1.1.1
SUBNET_MASK[0]=255.255.255.0
INTERFACE_NAME[0]=lan1
BROADCAST_ADDRESS[0]=5.1.1.255
INTERFACE_STATE[0]=up
#
ROUTE_DESTINATION[0]="net 5.2.1.0"
ROUTE_MASK[0]="255.255.255.0"
ROUTE_GATEWAY[0]="5.1.1.254"
ROUTE_COUNT[0]="1"
ROUTE_ARGS[0]=""
IP_ADDRESS[1]=5.1.2.0
SUBNET_MASK[1]=255.255.255.0
INTERFACE_NAME[1]=lan2
BROADCAST_ADDRESS[1]=5.1.2.255
INTERFACE_STATE[1]=up
#
ROUTE_DESTINATION[1]="net 5.2.2.0"
ROUTE_MASK[1]="255.255.255.0"
ROUTE_GATEWAY[1]="5.1.1.254"
ROUTE_COUNT[1]="1“
ROUTE_ARGS[1]=""
IP_ADDRESS[0]=5.2.1.1
SUBNET_MASK[0]=255.255.255.0
INTERFACE_NAME[0]=lan1
BROADCAST_ADDRESS[0]=5.2.1.255
INTERFACE_STATE[0]=up
#
ROUTE_DESTINATION[0]="net 5.1.1.0"
ROUTE_MASK[0]="255.255.255.0"
ROUTE_GATEWAY[0]="5.2.1.254"
ROUTE_COUNT[0]="1"
ROUTE_ARGS[0]=""
IP_ADDRESS[1]=5.2.2.1
SUBNET_MASK[1]=255.255.255.0
INTERFACE_NAME[1]=lan2
BROADCAST_ADDRESS[1]=5.2.2.255
INTERFACE_STATE[1]=up
#
ROUTE_DESTINATION[1]="net 5.1.2.0"
ROUTE_MASK[1]="255.255.255.0"
ROUTE_GATEWAY[1]="5.2.1.254"
ROUTE_COUNT[1]="1"
ROUTE_ARGS[1]=""
This shows that on node A, heartbeat packets from subnet 5.1.2.0 to subnet 5.2.2.0 are routed
through lan1 and the router gateway 5.1.1.254 (R1) of subnet 5.1.1.0. On node C, heartbeat
packets from subnet 5.2.2.0 to subnet 5.1.2.0 are also routed through lan1 and the router gateway
5.2.1.254 (R2) of subnet 5.2.1.0.
This configuration violates the requirement that the heartbeat subnets must be routed separately. If the
physical path through router R1 is broken, not only is the heartbeat between 5.1.1.0 and 5.2.1.0
disrupted but also the heartbeat between 5.1.2.0 and 5.2.2.0, even though the physical path through
router R2 is completely healthy. This configuration would compromise the heartbeat subnets’ high
availability.
Correct configuration of heartbeat routing
A correct routing configuration is shown in the below excerpt of /etc/rc.config.d/netconf.
The route and the gateway must be configured statically and added to