World Wide Names
The world wide name (WWN) in the switch is equivalent to the Ethernet MAC address. As with the MAC
address, you must uniquely associate the WWN to a single device. The principal switch selection and the
allocation of domain IDs rely on the WWN.
Cisco SAN switches support three network address authority (NAA) address formats. (see the following table).
Table 29: Standardized NAA WWN Formats
WWN FormatNAA TypeNAA Address
48-bit MAC address000 0000 0000bType 1 = 0001bIEEE 48-bit
address
48-bit MAC addressLocally assignedType 2 = 0010bIEEE
extended
VSID: 36 bitsIEEE company ID: 24 bitsType 5 = 0101bIEEE
registered
Changes to the world-wide names should be made by an administrator or individual who is completely
familiar with switch operations.
Caution
Verifying the WWN Configuration
Use the show wwn commands to display the status of the WWN configuration. This example shows how to
display the status of all WWNs:
switch# show wwn status
Type Configured Available Resvd. Alarm State
---- ---------- -------------- ------ -----------
1 64 48 ( 75%) 16 NONE
2,5 524288 442368 ( 84%) 73728 NONE
This example shows how to display the information for block ID 51:
switch# show wwn status block-id 51
WWNs in this block: 21:00:ac:16:5e:52:00:03 to 21:ff:ac:16:5e:52:00:03
Num. of WWNs:: Configured: 256 Allocated: 0 Available: 256
Block Allocation Status: FREE
This example shows how to display the WWN for a specific switch:
switch# show wwn switch
Switch WWN is 20:00:ac:16:5e:52:00:00
Link Initialization WWN Usage
Exchange Link Protocol (ELP) and Exchange Fabric Protocol (EFP) use WWNs during link initialization.
ELPs and EFPs both use the VSAN WWN by default during link initialization. However, the ELP usage
changes based on the peer switch’s usage:
Cisco Nexus 5500 Series NX-OS SAN Switching Configuration Guide, Release 7.x
218 OL-30895-01
Advanced Fibre Channel Features
World Wide Names
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