Fabric Extenders (FEs) are extensions of the fabric interconnects (FIs) and act as remote line cards to form a distributed modular fabric system. The fabric extension is accomplished through the FEX fabric link, which is the connection between the fabric interconnect and the FEX. A minimum of one connection between the FI and FEX is required to provide server connectivity. Depending on the FEX model, subsequent connections can be up to eight links, which provides added bandwidth to the servers.

The latest generation of the Cisco UCS Fabric extenders is the Cisco UCS 2408 FEX. It is used in the Cisco UCS 5108 chassis and allows for the connectivity to the Cisco 6454, 64108 and 6536 Fabric interconnects. The external connectivity is provided by 8x 25-Gbps FcoE SFP28 ports. This allows for up to 200-Gbps of bandwidth between the Cisco UCS 2408 FEX and the Cisco UCS 6400 and 6500 series fabric interconnect. As in a Cisco UCS 5108 blade chassis there are always two FEXs, one for the connectivity to each of the fabric interconnects, the combined bandwidth available to the chassis will be 400-Gbps.

The internal connectivity is supported by 32x 10-Gbps ports, which through the mid-plane provide 4x 10-Gbps bandwidth per server slot, per Cisco UCS 2408 FEX. Again, looking at the redundant connectivity of the Cisco UCS 5108, this secures a total of 80-Gbps of redundant bandwidth for each blade server in the chassis. The internal to external communication is delivered by the 1.04-Tbps of hardware forwarding capability of the FEX.

The Cisco UCS 2304 IOM (Fabric Extender) is an I/O module with 8x 40-Gigabit backplane ports and 4 40-Gigabit uplink ports (see Figure 12-11). It can be hot-plugged into the rear of a Cisco UCS 5108 blade server chassis. A maximum of two UCS 2304 IOMs can be installed in a chassis. The Cisco UCS 2304 IOM provides chassis management control and blade management control, including control of the chassis, fan trays, power supply units, and blades. It also multiplexes and forwards all traffic from the blade servers in the chassis to the 10-Gigabit Ethernet uplink network ports that connect to the fabric interconnect. The IOM can also connect to a peer IOM to form a cluster interconnect.

Figure 12-11 Cisco UCS 2300 IOM

Figure 12-12 shows how the FEX modules in the blade chassis connect to the FIs. The 5108 chassis accommodates the following FEXs:

Cisco UCS 2408

Cisco UCS 2304

Note

The Cisco UCS 2304 Fabric Extender is not compatible with the Cisco UCS 6200 Fabric Interconnect series.

Cisco UCS 2208XP

Cisco UCS 2204XP