Cisco has had Fabric Extenders in their Nexus datacenter switch portfolio since 2009. Since there are various models and they all are still appearing in the datacenters here is a summary of all the different FEX models.
Updated on 12-Oct-2014: Added Nexus 2348TQ.
Updated on 22-Apr-2015: Added Nexus 2332TQ.
Nexus 2148T was the first FEX for the Nexus line, announced in 2009. It has 48 host ports and four 10G SFP+ fabric ports. The host ports are 1G only, they don’t support 10 or 100 Mbps at all. The host ports don’t support port-channel configurations, meaning that you cannot bundle two or more ports on the same FEX towards the same host. Host vPC is supported however when using two single-homed FEXes. It means a maximum of two links for one host because there cannot be two links on the same FEX for the port-channel.
The low cost fabric port optical module is called a FET (Fabric Extender Transceiver, product code FET-10G). It is basically a short-range transceiver for multimode OM3 and OM4 fibers for up to 100 meters. It is not available separately, it must be purchased with the FEX in a bundle. The bundle then contains all the necessary FETs for full fabric capacity and connectivity. The FET concept is universal over all the FEX modules.
The oversubscription rate (when all ports are in use) is 1.2:1 (48G for hosts, 40G for fabric). The actual oversubscription rate between the host and fabric ports for all FEXes depend on the actual port usage. The capacity is not statically pinned between the host and fabric ports unless specifically configured on some models.
Nexus 2148T has been end-of-sale since November 2012.
Nexus 2248TP is the successor for 2148T, available since 2010. They are very similar with each other but the host ports now support also 100 Mbps and port-channeling as well.
The model naming now follows the convention that the letters indicate the connectivity types: TP = host ports are copper (T) and fabric ports are using 10G pluggable modules (P).
Nexus 2224TP is basically a 2248TP cut in half: 24 host ports and 2 fabric ports. The usual use case is to provide low-density 1G management connectivity to disk arrays and blade implementations where the data path is implemented with some other method like 10G/40G connectivity directly to the switches or other FEXes.
Nexus 2248TP-E is an enhanced version of the 2248TP FEX, available since 2011. It features bigger buffers and some features associated with the buffer handling and monitoring.
Nexus 2232PP was the first FEX with 10G host connectivity, available since 2010. It has 32 SFP+ host ports and 8 SFP+ fabric ports. It also supports FCoE for the 10G host ports. Host ports are 1G-capable with appropriate SFP modules.
A usual use case is blade chassis with pass-through modules or rack server installation: with two 2232PP FEXes you can provide 32 servers (like 2 chassis with 16 blades) with redundant 10G ethernet and FCoE connectivity.
The oversubscription rate is 4:1 (320G for hosts, 80G for fabric).
Nexus 2232TM (available since 2011) has 32 host ports which are 1/10G copper RJ-45 ports. It does not support FCoE. The fabric ports are implemented in a 8-port SFP+ module, thus the “M” designation. I’m not aware of any other module options here however.
The use case for 2232TM FEX is a 10Gbase-T server deployment.
Nexus 2232TM-E is an enhanced version of 2232TM, available since 2012. It supports FCoE on 10Gbase-T with Cat6a/7 cabling for up to 30 meters.
Nexus 2248PQ (available since 2013) is not to be confused with other previous 2248 variants. This has 48 host ports which are all SFP+ ports, supporting 1G and 10G pluggable modules. FCoE is supported with 10G.
The 4 fabric ports are QSFP+ ports (thus the “Q” designation). The QSFP+ ports can be used in either 40G or 4x10G mode. In addition to the usual QSFP+ pluggables (including the 40G-to-4x10G splitters) there is also a Cisco-specific FET-40G module, which is similar to the FET-10G (low-cost, limited-range, limited-use) but for 40G fabric connectivity.
The oversubscription rate is 3:1 (480G for hosts, 160G for fabric).
Nexus 2348UPQ was announced in August 2014. It has 48 SFP+ host ports and 6 QSFP+ fabric ports. The “U” in the designation comes from “Unified”, meaning that the host ports also support 2G/4G/8G/16G Fibre Channel with appropriate optics. At the moment it is hardware support only, the NX-OS software support will come later. 16G FC can only be used on 24 ports. FCoE is supported as usual with the 10G FEXes.
4 of the QSFP+ fabric ports can also be used for host connectivity using either 40G connectivity or splitting them to 4x10G ports. Software support for this is also yet coming.
The use case for 2348UPQ FEX may include situation where you have a mixed Ethernet/FCoE/FC server implementation, or if you have otherwise need to distribute some of your native FC ports farther from your Nexus parent switch.
The oversubscription rate is 2:1 (480G for hosts, 240G for fabric).
Nexus 2348TQ was announced in October 2014 and is similar to the Nexus 2348UPQ above. The major difference is that it has 48 10GBase-T (1G/10G) copper host ports instead of SFP+. FCoE is supported for Cat6a/7 cables up to 30 meters.
Minimum required NX-OS version is 7.1(0)N1(1) for Nexus 5500/5600/6000 series switches.
Nexus 2332TQ was announced in January 2015 and is in turn similar to the Nexus 2348TQ above. The major difference is the number of ports: there are 32 10GBase-T host ports and 4 QSFP+ fabric ports (two of which can be used for hosts when software is available), giving the same 2:1 oversubscription rate (320G for hosts, 160G for fabric).
Minimum required NX-OS version is 7.1(1)N1(1) for Nexus 5500/5600/6000 series switches.
Nexus B22 is the blade FEX family for Nexus switches. It consists of four different models that are used in the blade chassis:
- Nexus B22HP for HP c-Series
- Nexus B22IBM for IBM
- Nexus B22F for Fujitsu
- Nexus B22DELL for Dell
They have 14 or 16 1G/10G host ports (depending on the brand-specific model) and 8 SFP+ fabric ports. FCoE is supported. Nexus B22 is used to replace the usual Cisco or manufacturer-specific blade chassis switches and pass-through modules. The B22 FEXes are connected to the Nexus parent switches like the other FEXes. The form factor is just different between the Nexus 2000 series and B22 FEXes.
The oversubscription rate is 2:1 or 1.75:1 (160G or 140G for hosts, 80G for fabric).
For more information about all the FEXes above, see the Support home for the Fabric Extenders: http://www.cisco.com/c/en/us/support/switches/nexus-2000-series-fabric-extenders/tsd-products-support-series-home.html
For more information about the pluggable SFP+/QSFP+ modules, see Cisco 10GBASE SFP Modules Data Sheet and Cisco 40 Gigabit Modules QSFP Data Sheet.