Managing Serviceguard 12th Edition, March 2006

Understanding Serviceguard Hardware Configurations
Redundant Network Components
Chapter 2 41
Using Dual Attach FDDI Stations
Another way of obtaining redundant FDDI connections is to configure
dual attach stations on each node to create an FDDI ring, shown in
Figure 2-3. An advantage of this configuration is that only one slot is
used in the system card cage. In Figure 2-3, note that nodes 3 and 4 also
use Ethernet to provide connectivity outside the cluster.
Figure 2-3 Configuration with Dual Attach FDDI Stations
The use of dual attach cards gives protection against failures in both
cables and connectors, but does not protect against card failures. LAN
card failure would result in a package switching to another node.
Using a Serial (RS232) Heartbeat Line
Serviceguard supports a two-node configuration using serial (RS232)
communication for heartbeats only. You select this as an alternate
heartbeat interface to provide redundant heartbeat data.