Brocade FICON Administrator’s Guide (Supporting Fabric OS v7.3.0) - Manual (Page 83)

Triangular topology
The triangular topology shown in the figure below is a common FICON deployment for managing data
center recovery functions. In this topology, a switch is located in each of three sites and connected to
the other two forming a triangle. In most environments, the purpose of this configuration is to give the
host application the ability to connect to storage media at the other two sites, which allows it to recover
from an outage at either site. Meanwhile, the storage systems constantly synchronize between the two
storage sites.
FIGURE 21 Typical triangular setup
During normal operation, the routes from any device on one switch are a one-hop path to either of the
other two switches. However, if the path between any pair of switches fails, then a two-hop path is
available. Multi-hop paths are not certified for FICON configurations.
To get around the multiple-hop issue, use Enhanced TI Zoning to prohibit the connection between
E_Ports on the switches. For this setup you must define a device in two zones with failover disabled.
Triangular topology
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