HP StorageWorks 2/140 FW 08.01.00 McDATA Products in a SAN Environment Plannin - Page 108

Fabric WWN assignment, Domain_ID assignment, A Domain_ID

Page 108 highlights

Planning Considerations for Fibre Channel Topologies 3 - If you have three fabric elements and set two to Principal and one to Default, the element with the Principal setting that has the lowest WWN becomes the principal switch. - If you have three fabric elements and set two to Default and one to Never Principal, the element with the Default setting and the lowest WWN becomes the principal switch. Note that at least one director or switch in a multiswitch fabric needs to be set as Principal or Default. If all the fabric elements are set to Never Principal, all ISLs will segment. If all but one element is set to Never Principal and the element that was Principal goes offline, then all of the other ISLs will segment. NOTE: It is recommended to configure the switch priority as Default. In the audit log, note the Principal setting maps to a number code of 1, Default maps to a number code of 254, and Never Principal maps to a number code of 255. Number codes 2 through 253 are not used. • Fabric WWN assignment - The Fabric Manager application identifies fabrics using a fabric WWN. The fabric WWN is the same as the WWN of the fabric's principal switch. If a new principal switch is selected because of a change to the fabric topology, the fabric WWN changes to the WWN of the newly selected principal switch. • Domain_ID assignment - Each director or switch in a multiswitch fabric is identified by a unique Domain_ID that ranges between 1 and 31. A Domain_ID of 0 is invalid. Numerical Domain_IDs specified by a user are converted to hexadecimal format and used in 24-bit Fibre Channel addresses that uniquely identify source and destination ports in a fabric. Each fabric element is configured through the Element Manager application with a preferred Domain_ID. When a director or switch powers on and comes online, it requests a Domain_ID from the fabric's principal switch (indicating its preferred value as part of the request). If the requested Domain_ID is not allocated to the fabric, the Domain_ID is assigned to the requesting director or switch. If the requested Domain_ID is already allocated, an unused Domain_ID is assigned. 3-24 McDATA Products in a SAN Environment - Planning Manual

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3
3-24
McDATA Products in a SAN Environment - Planning Manual
Planning Considerations for Fibre Channel Topologies
If you have three fabric elements and set two to
Principal
and
one to
Default
, the element with the
Principal
setting that has
the lowest WWN becomes the principal switch.
If you have three fabric elements and set two to
Default
and
one to
Never Principal
, the element with the
Default
setting and
the lowest WWN becomes the principal switch.
Note that at least one director or switch in a multiswitch fabric
needs to be set as
Principal
or
Default
. If all the fabric elements are
set to
Never Principal
, all ISLs will segment. If all but one element
is set to
Never
Principal
and the element that was
Principal
goes
offline, then all of the other ISLs will segment.
NOTE:
It is recommended to configure the switch priority as
Default
.
In the audit log, note the
Principal
setting maps to a number code
of
1
,
Default
maps to a number code of
254
, and
Never Principal
maps to a number code of
255
. Number codes
2
through
253
are
not used.
Fabric WWN assignment -
The Fabric Manager application
identifies fabrics using a fabric WWN. The fabric WWN is the
same as the WWN of the fabric’s principal switch. If a new
principal switch is selected because of a change to the fabric
topology, the fabric WWN changes to the WWN of the newly
selected principal switch.
Domain_ID assignment -
Each director or switch in a
multiswitch fabric is identified by a unique Domain_ID that
ranges between
1
and
31
. A Domain_ID of
0
is invalid. Numerical
Domain_IDs specified by a user are converted to hexadecimal
format and used in 24-bit Fibre Channel addresses that uniquely
identify source and destination ports in a fabric.
Each fabric element is configured through the Element Manager
application with a preferred Domain_ID. When a director or
switch powers on and comes online, it requests a Domain_ID
from the fabric’s principal switch (indicating its preferred value
as part of the request). If the requested Domain_ID is not
allocated to the fabric, the Domain_ID is assigned to the
requesting director or switch. If the requested Domain_ID is
already allocated, an unused Domain_ID is assigned.