Brocade FICON Administrator’s Guide (Supporting Fabric OS v7.3.0) - Manual (Page 73)

• FICON networks with FCIP emulating and non-emulating tunnels do not support Dynamic Path
Selection (aptpolicy 3) configurations.
• When running FICON emulation features over an FCIP tunnel, it is highly recommended that both
switches providing the FCIP tunnel use the same Fabric OS release level.
High-integrity fabric requirements for cascaded configurations
You can use extended FICON connections between or through Brocade extension switches or blades
to create a cascaded FICON switched configuration. The fabric must be set up to provide a secure, or
high integrity, fabric to enable this configuration to operate in an IBM environment. Refer to
Meeting
high-integrity fabric requirements on page 33 for an explanation of these requirements.
FICON emulation requirement for a determinate path
FICON emulation processing creates FICON commands and responses on extended CHPIDs, and
intercepts all exchanges between a channel and a CU. For FICON emulation processing to function
correctly, all the exchanges between a channel and a CU must take a single tunnel path.
There are two ways to ensure a determinate path for FICON commands and responses:
• Define only one FCIP tunnel between sites.
• When multiple FICON emulation FCIP tunnels are required between a pair of chassis, define a new
logical switch pair (one logical switch in each chassis) for each tunnel. The logical switches and the
FCIP tunnel in those logical switches will provide a determinant path for all FICON sequences
between the host and device ports in that logical switch pair.
• When it is not possible to create logical switches, use Traffic Isolation Zones (TI Zones) to define
the host and device ports that traverse each required FCIP tunnel.
FCIP tunnel between sites
Brocade extension switches and blades use FCIP trunking features to overcome the limitation of one
Ethernet interface, one IP address, and one FCIP tunnel. In Fabric OS v6.3 and later, an FCIP tunnel is
created with multiple FCIP circuits over different IP interfaces to provide WAN load balancing and
failover recovery in the event of a limited WAN outage. This provides a highly redundant WAN
configuration for all FICON or FCP emulation technologies with Fabric OS. The figure below shows that
a tunnel can have up to four circuits per GbE port.
FIGURE 20 FCIP tunnel and circuits
High-integrity fabric requirements for cascaded configurations
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