Specifications

8 Getting Started with the McDATA Intrepid FICON Director
1.3.2 Cascaded FICON Director configuration
In a cascaded FICON Director connection, at least three Fibre Channel (FC) links are needed
in the channel-control unit path. One is between the FICON channel card (N_Port) and the
FICON Director port (F_Port), then internally within the switch (through the backplane) to
another port (E_Port) that connects to the second FICON Director E_Port via the second FC
link, and then to a FICON adapter card in the control unit (N_Port) via the third FC link. With
this configuration, the connection between sites can consist of multiple FC links.
An example of cascaded FICON Directors is shown in Figure 1-4.
Multiple channel images and multiple control unit images can share resources of the Fibre
Channel link and Fibre Channel switches, such that multiplexed I/O operations can be
performed.
Channels and control unit links can be attached to the Fibre Channel switches in any
combination, depending on configuration requirements and on available switch ports.
Sharing a control unit through a Fibre Channel switch means that communication from a
number of channels to the control unit can take place either over one switch-to-CU link (in the
case where a control unit has only one link to the Fibre Channel switch), or over multiple link
interfaces in the case where a control unit has more than one link to the Fibre Channel switch.
Just one Fibre Channel link is attached to a FICON channel in a cascaded FICON Director
configuration. However, from the FC switch (FICON Director) the FICON channel can
communicate with a number of FICON CUs on different ports of the second FC switch. Once
at the control unit, the same control unit and device addressing capability exists as for a
point-to-point configuration. However, the communication and addressing capability is greatly
increased for the channel when connected to a FC switch with the ability to use the domain
and port address portion of the 24-bit N_Port address (8 bits for the domain and 8 bits for the
port) to access multiple control units. Note the domain address portion of the FC 24-bit port
address is different since there are two FC switches in the channel-to-control unit path.
Figure 1-4 Cascaded FICON Directors configuration
FICON
Channel
Control Unit
FICON Port
F i b r e C h a n n e l
FC Links
FC Links
Server
Fabric
Storage
FICON
Channel
Control Unit
FICON Port
Fabric Login (FLOGI)
Determine fabric connection
(Point-to-Point or Switched)
Processor
Channel Image
Channel N_Port
zSeries Configuration Definition - Path Addressing
Storage Unit
CU Image
CU N_Port
Link (Switch@ Port@)
2-Byte Link Address
FC
Switch
FC
Switch
Switch (entry Switch@)
Site A
Site B
FC
Links