HP Serviceguard Extended Distance Cluster for Linux A.12.00.00 Deployment Guide, March 2014

be configured. If the DWDM box supports multiple active DWDM links, that feature can be
used instead of the redundant standby feature.
• At least two dark fiber optic links are required between each Primary data center, each fibre
link routed differently to prevent the “backhoe problem.” It is allowable to have only a single
fibre link routed from each Primary data center to the third location, however in order to survive
the loss of a link between a Primary data center and the third data center, the network routing
should be configured so that a Primary data center can also reach the Arbitrator via a route
passing through the other Primary data center.
• Fibre Channel switches must be used in a DWDM configuration; Fibre Channel hubs are not
supported. Direct Fabric Attach mode must be used for the ports connected to the DWDM
link.
See the HP Configuration Guide, available through your HP representative, for more information
on supported devices.
2.5 Guidelines on DWDM Links for Network and Data 19