Specifications

Switch Considerations for FICON
McDATA UMD Switch (Firmware Revision 1.5 or above)
C-5
McDATA UMD Switch (Firmware Revision 1.5 or above)
The McDATA UMD has a feature called "flow groups" that must be enabled in cascaded
configurations in order for Ultranet FICON emulation support to operate correctly. In the case of
XRC operations in UMD cascaded configurations that have multiple extended ISLs, channel
detected errors will occur when the "flow groups" feature is not enabled or defined correctly. In the
case of FICON tape pipelining configurations in UMD cascaded configurations with multiple
extended ISLs, pipelining will not be entered if this feature is not enabled or if it is incorrectly
configured.
To configure flow groups, the ISL and associated devices (ports) should be added to separately
defined flow groups. Your ISLs should be set as exclusive. You should then remove any alternate
paths and disable failover and failback in your ISL Path Groups.
Note: The UMD has a default setting of 100 bb_credits on all FICON extended ports.
Cisco MDS 9000 Switch
The Cisco switch "VSAN" feature must be utilized in ISL configurations in order for Ultranet
FICON emulation support to operate correctly. The VSAN must be configured such that all
elements (devices) within the VSAN exchange data over a single ISL
McDATA recommends Cisco MDS Firmware Revision: 2.1.2e or above. 2.0.2b maybe used with
a minimum Edge level of 3.1.3.2.2 or 3.1.5 and above. The Cisco 2.0.2b version has known
problems with recovery from power failures.
Note: The MDS 9000, by default, will be allowed the maximum of 120 bb_credits on all FICON
extended ports. That is the limit for the Ultranet Edge platforms.
FICON Emulation Requirements for Switches
For MCDATA Emulation processing to function correctly, the responses to Host I/O (channel I/O)
must be received on the same on the same ISL as the commands. This is contrary to a normal
cascaded FICON switch configuration in that the switches treat the ISLs as just a path to the peer
switch with no consideration for the CHPIDs that are using the paths. Switches will normally route
inbound ports to a remote switch over the least used operational ISL to that remote switch. In those
configurations, the ISL used for commands or data frames from a Channel to a CU on a CHPID
may not be the same ISL used by the switch to route responses back to the Channel FICON
interface.