HP StorageWorks P9000 Mainframe Host Attachment and Operations Guide: P9500 Disk Array (AV400-96332, January 2011)

Figure 8 Example of a point-to-point topology
Switched point-to-point topology
A FICON channel in FICON native mode connects one or more processor images to a Fibre
Channel link, which connects to a Fibre Channel switch, and then dynamically to one or more FC
switch ports (internally within the switch). From the switch ports, another Fibre Channel link to
FICON CU ports interconnects with one or more control units and/or images (logical control units).
This forms a switched point-to-point configuration, as shown in Figure 9 (page 16).
Multiple channel images and multiple control unit images can share the resources of the Fibre
Channel link and Fibre Channel switch, permitting multiplexed I/O operations. Channels and
control unit links can be attached to the Fibre Channel switch in any combination, depending on
configuration requirements and available Fibre Channel switch resources.
Sharing a control unit through a Fibre Channel switch allows communication between a number
of channels and the control unit to occur either:
• Over one switch-to-CU link, such as when a control unit has only one link to the Fibre Channel
switch, or
• Over multiple-link interfaces, such as when a control unit has more than one link to the Fibre
Channel switch.
In a FICON switched point-to-point topology, one Fibre Channel link is attached to the FICON
channel. From the switch, the FICON channel communicates with a number of FICON CUs on
different switch ports. At the control unit, the control unit and device-addressing capability is the
same as the point-to-point topology. However, communication and addressing capabilities are
increased for the channel when it is connected to a Fibre Channel switch, and can use the domain
and port address portion of the 24-bit N_Port address to access multiple control units.
The communication path between a channel and a control unit consists of the physical channel
path and the logical path. In a FICON switched point-to-point topology with a single switch, the
physical paths are the Fibre Channel links (interconnection of two Fibre Channel links connected
by a Fibre Channel switch) that provide the physical transmission path between a channel and a
control unit.
Attaching FICON/zHPF CHAs 15