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•
FICON port-to-port connectivity is hardware enforced, while
FCP port-to-port connectivity is software or hardware enforced
(depending on the director or switch firmware release level).
— FICON architecture controls connectivity through a
host-based HCD program, the CUP, and a director or
switch-resident PDCM array. The CUP and PDCM array
support hardware enforcement of connectivity control to all
port connections; therefore when a director or switch is set to
FICON management style, zoning information is restricted by
the hardware instead of by the name server.
— When a director or switch is set to open systems management
style, CUP support and the PDCM array are disabled. For
FICON devices attached to the director or switch, the user
must manage connectivity to match logical port addressing
established through the host-based HCD program. For
example if a FICON hosts expects connectivity through logical
port address 1C, the user must ensure the host is connected to
physical port number 24. Refer to
for physical port number and logical port address maps.
•
The FCP protocol supports multiple domains (multiswitch
fabrics). The FICON protocol may or may not be limited to a
single domain (single-switch fabric), depending on the director or
switch firmware release level as follows:
— For earlier versions of director or switch firmware (prior to
Enterprise Operating System (E/OS) Version 4.0), the FICON
protocol is limited to a single domain (single-switch fabric)
due to single-byte Fibre Channel link address limitations
inherited from ESCON. Consequently, when a director or
switch is set to FICON management style (FICON compliant),
E_Port connections (ISLs) are not allowed with another fabric
switch. The director or switch reports an attempted E_Port
connection as invalid and prevents the port from coming
online.
— For later versions of director or switch firmware (E/OS
Version 4.0 and later), the domain field of the destination ID is
added to the Fibre Channel link address, thus specifying the
link address on source and target fabric elements and enabling
E_Port (ISL) connectivity. This connectivity is called FICON
cascading. For additional information, refer to
Cascading.
Planning Considerations for Fibre Channel Topologies
Planning Considerations for Fibre Channel Topologies
Figure 3-17
and
Figure 3-18
FICON
3-45
3
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