You want to ensure the uniqueness of the Cisco UCS WWNNs and WWPNs in the SAN for a FlexPod solution. In this situation, Cisco recommends using which…

Cisco UCS Manager automatically generates World Wide Names (WWNs) for server vHBAs from pools. To guarantee uniqueness and prevent conflicts with physical devices in the SAN, Cisco was allocated a specific Organizationally Unique Identifier (OUI) for this purpose. The recommended and default prefix for all WWN pools (both WWNN and WWPN) is 20:00:00:25:B5:XX:XX:XX. The 00:25:B5 is the Cisco OUI, and the 20: prefix indicates it is a virtualized address. Using this standard prefix is a critical best practice in FlexPod deployments to ensure stable and predictable SAN operations.

A. 30:00:00:25:B5:XX:XX:XX: This is not the Cisco-recommended prefix for virtual WWNs and would not conform to established best practices.

B. 40:00:00:25:B5:XX:XX:XX: This prefix is not the standard used by Cisco UCS for generating unique virtual WWNs.

D. 60:00:00:25:B5:XX:XX:XX: This is an incorrect prefix; the standard prefix for Cisco virtual WWNs begins with 20:.

1. Cisco UCS Manager GUI Configuration Guide, Release 4.0: In the "Creating a WWN Pool" section, the guide states, "The WWN prefix must be in the 20:00:00:00:00:00:00:00 to 20:FF:FF:FF:FF:FF:FF or 50:00:00:00:00:00:00:00 to 5F:FF:FF:FF:FF:FF:FF range. We recommend that you use the prefix 20:00:00:25:B5:00:00:00." (See Chapter: LAN and SAN Connectivity, Section: SAN Pools, Subsection: Creating a WWN Pool).

2. FlexPod Datacenter with VMware vSphere 7.0, Cisco UCS 4th Generation, and NetApp ONTAP 9.8 (Cisco Validated Design): In the "Cisco UCS Configuration" chapter, under the "Configure WWNN Pool" and "Configure WWPN Pool" sections, the step-by-step instructions explicitly show the creation of pools using the prefix 20:00:00:25:B5:00:00:00. (See Figures 37 and 39 in the "Configure Pools" section).

3. Cisco UCS Best Practices for NetApp Storage (White Paper): This document reinforces the use of the standard Cisco prefix. In the section on "WWN Pools," it states, "The default WWN prefix is 20:00:00:25:B5:00:00:00. This prefix is derived from the Cisco OUI 00:25:B5 and ensures that the WWNs assigned to the vHBAs are unique." (See Section: Cisco UCS Configuration Best Practices, Subsection: WWN Pools).