Designing Disaster Tolerant High Availability Clusters, 10th Edition, March 2003 (B7660-90013)

Disaster Tolerance and Recovery in an MC/ServiceGuard Cluster
Disaster Tolerant Architecture Guidelines
Chapter 140
These FDDI options are shown in Figure 1-11.
Figure 1-11 Highly Available FDDI Network: Two Options
Ethernet networks can also be used to connect nodes in a disaster
tolerant architecture within the following guidelines:
• Each node is connected to redundant hubs and bridges using two
10BaseT or 100BaseT host adapters. Bridges, repeaters, or other
components that convert from copper to fiber cable may be used to
span longer distances.
• Redundant Ethernet links must be routed in the opposite directions,
otherwise a data center failure can cause a failure of both networks.
Figure 1-12 shows one Ethernet link routed from data center A, to B,
to C. The other is routed from A, to C, to B. If both links were routed
Data Center A
node 1
node 2
Data Center B
node 3
node 4
Data Center C
node 5 node 6
S
S
S
S
C
C
C
C
FDDI SAS (Single Attach)
with concentrator
C
FDDI DAS (Dual Attach)
=
S
=
with bypass switch