What is Fabric Extenders

-->  Cisco launched the Nexus 2000 Fabric Extender series in 2009.

--> Fabric Extender Switch can't be used as a standalone Ethernet switch, it should be used as remote line card for parent switch.

--> An FEX has no management interface, but instead has to be connected to a Nexus 5000 or 7000, after which it becomes a logical part of that parent switch.

--> All management operations should be performed on Parent Switch. Parent switch can be Nexus 9K/7K/5K for the Fabric Extender.

--> Fabric Extenders does not have any console or vty ports.

--> NX-OS automatically downloaded to Fabrix Extender from the Parent Switch.

--> Connection from FEX to parent switch is done via an SFP module with fiber, or a Cisco Twinax cable, which is an ethernet-like copper cable with the SFP already attached to it on both sides.

-->  Depending on the FEX model, there are two or four SFP uplinks possible, just like most Catalyst switches.

--> Fabric Extender does not have or store Mac address table because of that there is no local switching in Fabric Extender.

--> Traffic between local ports of Fabric Extender must flow via an uplink to parent switch then back to Fabric Extender.

--> It is not recommended to configure FEX for East to West traffic ( Server -- Server) because of no local switching feature available in Fabric Extender.

--> Fabric Extenders does not support Private vlans.

--> There are two types of interfaces are used when we are working with fabric extenders,

1) Fabric Interface 

--> A fabric interface is the corresponding interface that is connected on the parent switch.

--> This interface is enabled when you enter the switchport mode fex-fabric command on the parent switch.

2) Host Interface

--> Host interface is an Ethernet host interface for connection to a server or host system.

--> This interface is present on Fabric Extender.


Configuration:

Step1: Enable the FEX feature in the parent switch.

N5K(config)# feature fex


Step 2: Create a FEX instance 

N5k(config)#fex 150

Note: Number can range from 100 to 199.

Step3: Configure the interface on the Parent switch ( In this case Nexus 5k) that are used for connecting the FEX.

N5K(config)# int ethernet range 1/1-2
N5k(config-if)#switchport
N5k(config-if)#switchport mode fex-fabric
N5k(config-if)#channel-group 150

Step4: Create the port-channel and associate the FEX with it. 

N5k(config)#interface port-channel 150
N5k(config-if)#fex associate 150

Verification: N5K# show fex

Ref: Cisco.com

Md.Kareemoddin

CCIE# 54759