Brocade FICON Administrator’s Guide (Supporting Fabric OS v7.3.0) - Manual (Page 47)

• The default switch is being used for FICON and no 48 or 64 port blades are installed in the chassis.
The default switch address mode 0 will be 8-bit area mode with zero based addressing (which
supports FICON) instead of 10-bit addressing.
• The chassis is not enabled for virtual fabrics and 48 or 64 port blades are not installed in the
chassis.
Mode 1 (zero-based addressing)
Mode 1 is the recommended mode for FICON. In this addressing mode, port numbers are assigned
starting with 00 as the ports are moved into the logical switch. Typically, several ports are moved at
once. The bottom port in the left-most port column on the blade has the lowest slot number and is
assigned 00. Addresses increment by one as ports progress up the blade from 00 and to the next
column on the right. Addresses continue to increment by one as they move to the next blade. This is
different than how port addresses are assigned in a chassis that is not enabled for Virtual Fabrics.
The ALPA is always 0x00. Therefore, Mode 1 addressing limits the maximum switch size to 256 ports.
Mode 1 does not use any of the ALPA bits and may be preferred for native FCP with zVM to allow up to
256 (255 practical) NPIV logins.
NOTE
Although port addresses are assigned when moved to a logical switch, the address is not bound to the
port. To ensure that the link address for a control unit attached to a port does not change, the
portAddress command must be used to bind the address to the port even if you are not changing the
port address assignments. Refer to
Sequential address binding on page 107 for a list of commands
that will bind ports on DCX or DCX 8510-8 Backbones fully populated with 32-port blades.
Mode 2 (port-based addressing)
Port-based addressing follows a default port numbering scheme that starts with 00 for the port on the
bottom leftmost column of the blade in slot 1 and increments for each port going up the blade. For a
DCX and DCX 8510-8 Backbone, the rightmost port column on the blade starts with 0x80, and port
numbering increments going up the blade. Subsequent blade slots follow the same port numbering
scheme with an offset of 0x80. The ALPA is always 0x00 except on the 48-port blades. The 48-port
blades use bits in the ALPA for the upper 16 ports on bladed switches that support more than 256 ports.
This is why the 48-port blade in the DCX and DCX 8510-8 Backbones is only supported with zero-
based addressing. The DCX-4S and DCX 8510-4 Backbones do not use the ALPA bits with the 48-port
blades. Port-based addressing is used in a Brocade switch or Backbone not enabled for Virtual Fabrics.
Refer to Port-Based Address Binding on page 112 for a list of commands that will allow DCX or DCX
8510-8 Backbones fully populated with 32-port blades that are configured for zero-based addressing to
use port-based addresses.
Changing the addressing mode
Changing the addressing mode can have serious implications. After changing the addressing mode, the
following actions occur:
• Physical ports can receive new area assignments.
• Port addresses that are referenced in an Input/Output Configuration Data Set (IOCDS) generation
can be associated with entirely new physical ports.
To change the addressing mode, use the following procedure.
Mode 1 (zero-based addressing)
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