Specifications

When you attach FICON products to switches or directors, you cannot use cascade
switches. You cannot configure a fabric of multiple interconnected directors and
have a FICON channel attached to one director communicate to a FICON control
unit that is attached to another director. The FICON architecture prohibits this
capability. The reason for the restriction is because the base S/390 and zSeries I/O
architecture uses a single byte for addressing the I/O devices. This one-byte I/O
address is not compatible with the fibre-channel, 3-byte port address. The FICON
solution to this problem is to disallow switch cascading.
Chapter 7. Attaching to an IBM S/390 or IBM eServer zSeries host 81
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