HP Cisco Nexus 5000 Cisco MDS 9000 Family CLI Configuration Guide - Release 4. - Page 494

FC IDs Chapter 18 Configuring Domain Parameters Send documentation comments to [email protected] 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: • 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 NX-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. Enabling Contiguous Domain ID Assignments To enable contiguous domains in a specific VSAN (or a range of VSANs), follow these steps: Step 1 Step 2 Command Purpose switch# config t switch(config)# Enters configuration mode. switch(config)# fcdomain contiguous-allocation Enables the contiguous allocation option in vsan 81-83 VSAN 81 through 83. Note The contiguous-allocation option takes immediate effect at runtime. You do not need to restart the fcdomain. switch(config)# no fcdomain contiguous-allocation vsan 1030 Disables the contiguous allocation option and reverts it to the factory default in VSAN 1030. FC IDs 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: • 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. This section describes configuring FC IDs and includes the following topics: 18-14 Cisco MDS 9000 Family CLI Configuration Guide OL-18084-01, Cisco MDS NX-OS Release 4.x