Fabric Extenders (FEX) modules are also known as IO Modules (IOMs). These modules serve as line cards to the Fabric Interconnects, in the same way as the Nexus series switches' remote line cards. IOMs also provide interface connections to blade servers. IOMs multiplex data from blade servers and provide this data to Fabric Interconnects and do the same in the reverse direction. In production environments, IOMs are always used in pairs to provide redundancy and failover.
Apart from data transfer between chassis and Fabric Interconnects, IOMs provide two other functions:
- Chassis Management Controller (CMC): This monitors chassis components, such as fan units, power supplies, and chassis temperature. It also reads chassis components' identification data and detects the insertion and removal of blade servers.
- Chassis Management Switch (CMS): This provides fast Ethernet links to embedded Cisco Integrated Management Controller (CIMC) instances on blade servers for KVM access, serial over LAN (SoL) access, and Intelligent Platform Management Interface (IPMI) data to travel from individual blades to FIs for monitoring and management purposes.
The following is a diagram of the Cisco UCS Fabric Extender (IO Module):
The Cisco UCS 2304 Fabric Extender is third-generation hardware and provides native 40 Gig Ethernet/FCoE uplinks to the Fabric Interconnect 6300 series. It includes 4x40 Gig Network Interfaces (NIFs) and 32x10 Gig backend ports to blade servers.
The specifications of the 2304XP are as follows:
- 4x40 Gbps fabric ports for connecting to the Fabric Interconnect
- 32x10 Gbps server-facing ports with FCoE
- 160 Gbps throughput
The Cisco UCS 2208XP Fabric Extender is second-generation hardware and provides 10 Gig Ethernet/FCoE uplinks to the Fabric Interconnect 6200/6300 series. It includes 8x10 Gig network interfaces and 32x10 Gig backend ports to blade servers.
Its specifications are as follows:
- 8x10 Gbps fabric ports for connecting to the Fabric Interconnect
- 32x10 Gbps server-facing ports with FCoE
- 80 Gbps throughput
The Cisco UCS 2204 Fabric Extender is second-generation hardware and provides 10 Gig Ethernet/FCoE uplinks to the Fabric Interconnect 6200/6300 series. It includes 4x10 Gig network interfaces and 32x10 Gig backend ports to blade servers.
The specifications of the 2204XP are as follows:
- 4x10 Gbps fabric ports for connecting to the Fabric Interconnect
- 16x10 Gbps server-facing ports with FCoE
- 40 Gbps throughput
The Cisco Nexus 2348UPQ 10GE Fabric Extender is third-generation hardware and provides native 40 Gig Ethernet upstream to the Fabric Interconnect 6200/6300 series and 1/10 Gig downstream connectivity to rack servers and other appliances.
The specifications of the N2248UPQ are as follows:
- 6x40 Gbps fabric ports for connecting to the Fabric Interconnect
- 48x10 Gbps server-facing ports
- 240 Gbps throughput