A fully redundant Cisco Unified Computing System consists of two independent fabric planes: Fabric A and Fabric B. Each plane consists of a central fabric interconnect connected to an I/O module (Fabric Extender) in each blade chassis. The two fabric interconnects are completely independent from the perspective of the data plane; the Cisco UCS can function with a single fabric interconnect if the other fabric is offline or not provisioned (see Figure 12-24).

Figure 12-24 UCS Fabric Interconnect (FI) Status

The following steps show how to determine the primary fabric interconnect:

Step 1. In the Navigation pane, click Equipment.

Step 2. Expand Equipment > Fabric Interconnects.

Step 3. Click the fabric interconnect for which you want to identify the role.

Step 4. In the Work pane, click the General tab.

Step 5. In the General tab, click the down arrows on the High Availability Details bar to expand that area.

Step 6. View the Leadership field to determine whether the fabric interconnect is primary or subordinate.

Note

If the admin password is lost, you can determine the primary and secondary roles of the fabric interconnects in a cluster by opening the Cisco UCS Manager GUI from the IP addresses of both fabric interconnects. The subordinate fabric interconnect fails with the following message: “UCSM GUI is not available on secondary node.”

The fabric interconnect is the core component of the Cisco UCS. Cisco UCS Fabric Interconnects provide uplink access to LAN, SAN, and out-of-band management segments, as shown in Figure 12-25. Cisco UCS infrastructure management is handled through the embedded management software, the Cisco UCS Manager, for both hardware and software management. The Cisco UCS Fabric Interconnects are top-of-rack devices and provide unified access to the Cisco UCS domain.

Figure 12-25 Cisco UCS Components Logical Connectivity

All network endpoints, such as host bus adapters (HBAs) and management entities such as Cisco Integrated Management Controllers (CIMCs), are dual-connected to both fabric planes and thus can work in an active-active configuration.

Virtual port channels (vPCs) are not supported on the fabric interconnects, although the upstream LAN switches to which they connect can be vPC or Virtual Switching System (VSS) peers.

Cisco UCS Fabric Interconnects provide network connectivity and management for the connected servers. They run the Cisco UCS Manager control software and consist of expansion modules for the Cisco UCS Manager software.