McDATA StorageWorks 2/140 - Director Switch Planning Manual page 109

If two operational fabrics join, they determine if any Domain_ID
conflicts exist between the fabrics. If one or more conflicts exist,
the interconnecting ISL E_Ports segment to prevent the fabrics
from joining. To prevent this problem, it is recommended that all
directors and switches be assigned a unique preferred
Domain_ID. This is important if zoning is implemented through
port number (and by default Domain_ID) rather that WWN.
When assigning preferred Domain_IDs in an open fabric with
directors and switches supplied by multiple OEMs, be aware of
the following:
— For Intrepid 6000-series directors and Sphereon-series fabric
switches, the firmware adds a base offset of 96 (hexadecimal
60) to the numerically-assigned preferred Domain_ID.
Therefore, if a user assigns a director or switch a numerical
preferred Domain_ID of 1, the firmware assigns a hexadecimal
Domain_ID of 61.
— For the Intrepid 10000 Director and Eclipse-series SAN
routers, the firmware does not add a base offset to the
numerically-assigned preferred Domain_ID.
— For non-McDATA directors and switches, the product
firmware may not add a base offset to the numerical preferred
Domain_ID or may add a different hexadecimal base offset
(not 60).
As a consequence of this variable base offset and hexadecimal
conversion, Domain_ID conflicts may exist in an open fabric,
even if each participating director and switch is assigned a unique
numerical Domain_ID. To determine the method of preferred
Domain_ID assignment for a product, refer to the supporting
OEM publications for the product or contact McDATA.
NOTE: Do not assign Domain_ID 30 or Domain_ID 31 to a fabric
element. In a routed SAN, these proxy Domain_IDs are assigned to
routing domains.
• Path selection - Directors and fabric switches are not manually
configured with data transmission paths to each other.
Participating fabric elements automatically exchange information
to determine the fabric topology and resulting minimum-hop
data transfer paths through the fabric. These paths route Fibre
Planning Considerations for Fibre Channel Topologies
Planning Considerations for Fibre Channel Topologies
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