hesela.devWorld Wide Name (Fibre Channel)
In Fibre Channel, a World Wide Name is a persistent 64-bit name for an entity such as a node or port, distinct from a port's fabric address.
WWPN names a port and WWNN names a node. RFC 4338 distinguishes a nonvolatile port name from the volatile 24-bit N_Port_ID used for communication. These identify different aspects of the connection, not interchangeable representations of a logical volume. [1] [2]
Linux's NPIV documentation assigns responsibility for virtual-port WWN allocation and uniqueness to the managing administrative entity. The name is not evidence of hardware authenticity or permission to write; that is an engineering boundary, not a claimed security property of the identifier. [2]
Do not automatically equate an FC WWPN with a multipath WWID. The pinned multipath-tools manual groups paths by a selected WWID obtained through its configured identification method, including udev attributes. A port name by itself does not select which logical unit behind that port is intended. [3]
Relations
Citations
- RFC 4338 (January 2006), section 2.2: Fibre Channel identifiers and login
- Linux v6.12: SCSI FC transport documentation, virtual-port names and administrative uniqueness responsibility
- multipath-tools at d53932bdbee02f440518ea384e63d7c4d3f66685: multipath.conf(5), uid_attribute and WWID generation
Sources & caveats
- Primary documentation and pinned implementation review on 2026-11-03; no device interrogation, failover experiment or global-uniqueness measurement.