S e n d d o c u m e n t a t i o n c o m m e n t s t o m d s f e e d b a c k - d o c @ c i s c o . c o m
About Contiguous Domain ID Assignments
By default, the contiguous domain assignment is disabled. When a subordinate switch requests the
principal switch for two or more domains and the domains are not contiguous, the following cases apply:
Enabling Contiguous Domain ID Assignments
To enable contiguous domains in a specific VSAN (or a range of VSANs), follow these steps:
switch# config t
switch(config)# fcdomain contiguous-allocation
switch(config)# no fcdomain
contiguous-allocation vsan 1030
When an N or NL port logs into a Cisco MDS 9000 Family switch, it is assigned an FC ID. By default,
the persistent FC ID feature is enabled. If this feature is disabled, the following consequences apply:
This section describes configuring FC IDs and includes the following topics:
Cisco MDS 9000 Family CLI Configuration Guide
If the contiguous domain assignment is enabled in the principal switch, the principal switch locates
contiguous domains and assigns them to the subordinate switches. If contiguous domains are not
available, the SAN-OS software rejects this request.
If the contiguous domain assignment is disabled in the principal switch, the principal switch assigns
the available domains to the subordinate switch.
An N or NL port logs into a Cisco MDS 9000 Family switch. The WWN of the requesting N or NL
port and the assigned FC ID are retained and stored in a volatile cache. The contents of this volatile
cache are not saved across reboots.
The switch is designed to preserve the binding FC ID to the WWN on a best-effort basis. For
example, if one N port disconnects from the switch and its FC ID is requested by another device,
this request is granted and the WWN with the initial FC ID association is released.
The volatile cache stores up to 4000 entries of WWN to FC ID binding. If this cache is full, a new
(more recent) entry overwrites the oldest entry in the cache. In this case, the corresponding WWN
to FC ID association for the oldest entry is lost.
The switch connection behavior differs between N ports and NL ports:
N ports receive the same FC IDs if disconnected and reconnected to any port within the same
switch (as long as it belongs to the same VSAN).
NL ports receive the same FC IDs only if connected back to the same port on the switch to which
they were originally connected.
Configuring Domain Parameters
Enters configuration mode.
Enables the contiguous allocation option in
VSAN 81 through 83.
The contiguous-allocation option
takes immediate effect at runtime. You
do not need to restart the fcdomain.
Disables the contiguous allocation option and
reverts it to the factory default in VSAN 1030.
OL-16184-01, Cisco MDS SAN-OS Release 3.x