Specifications

Switch Considerations for FICON
FICON Emulation Requirements for Switches
C-6 UltraNet Storage Router 3000 Version 3.2 Release Notes
There are features in all the McDATA switch products that can be used to define rules for ISL
usage. The switch specific rules are used to select the ISL that is used for a combination of inbound
ports referencing a remote switch domain. Rules can be defined within the Switch Configuration to
at least encourage the switch to route the traffic over a specific ISL.
McDATA i10k, 6140, 6064, 4700, and 3232 Switches - Preferred Path Feature
The McDATA switches have a feature that is called Preferred Path. The name is accurate in that the
switch will use that ISL if it is operational when frames are received from that port that are destined
for the remote domain. If that ISL is not operational, the switch will route via any available ISL to
that domain. When that happens, the FICON emulation processing will fail. To avoid that
situation, the allow\prohibit feature must also be used.
McDATA i10k, 6140, 6064, 4700, and 3232 Switches - Allow\Prohibit Feature
The allow/prohibit feature allows a McDATA user to configure the ISL ports that are allowed to be
routed to for all inbound ports. In order to avoid configurations that would not function in a
McDATA FICON emulation configuration, all other ISL ports should be prohibited for use for
traffic from that port. This feature, if configured, would remove automatic ISL failover, but would
also always ensure that McDATA emulation processing could function if the ISL was available.
In both switches, the combination of inbound port and destination domain (switch) are used to
define the ISL that should be used for the flow between the cascaded switches.
McDATA's emulation processing creates FICON commands and responses on extended FICON
CHPIDs, and must know exactly what exchanges are occurring between a Channel and a CU on a
CHPID to function correctly. Therefore, the same ISL is used for commands to a CU and for the
responses to those commands to the Channel.