FEX Pre-provisioning

Today, in the highlight: FEX pre-provisioning.

What is a FEX? It is Fabric Extender, a “remote line card” used in Cisco Nexus series switches. It is managed through its parent switch (like Nexus 5000 or Nexus 7000) but looks externally like a traditional data center access switch.

In some cases you would like to configure the FEX interfaces before the FEX is actually online. For example, when enabling NPV mode the configuration is deleted and you would maybe like to configure the ports before the links go up on the FEXes.

First, let’s try to show the configuration of the not-yet-existing FEX port:

nexus5596(config)# sh run int e101/1/1
Invalid range at '^' marker.

The configuration does not exist, and you cannot enter the interface configuration mode for the FEX ports because they don’t exist yet as the FEX is not yet connected. Let’s pre-provision the FEX 101:

nexus5596(config)# slot 101
nexus5596(config-slot)# provision model ?
  N2K-B22HP      Fabric Extender 16x10G Module
  N2K-C2148T     Fabric Extender 48x1G 4x10G Module
  N2K-C2232P     Fabric Extender 32x10G Module
  N2K-C2232TM    Fabric Extender 32x10G Module - Zephyr
  N2K-C2248GV+P  Fabric Extender 48x1G 4x10G POE Module
  N2K-C2248T     Fabric Extender 48x1G 4x10G Module
  N2K-N2224TP    Fabric Extender 24x1G 2x10G SFP+ Module
  N55-M16FP      Cisco 16 port Port Fiber Channel Expansion Module 16 x SFP
  N55-M16P       Cisco 16x10G Ethernet Expansion Module
  N55-M16UP      Cisco 16x10G Flexible Ethernet Expansion Module
  N55-M8P8FP     Cisco 8 Port 1/2/4/8G FC + 8 Port 10G Ethernet Expansion Module
  N5K-M1008      Cisco 8 Port Fiber Channel Expansion Module 8 x SFP
  N5K-M1060      Cisco 6 Port Fiber Channel Expansion Module 6 x SFP
  N5K-M1404      Expansion Module 4 x 10GBase-T LAN, 4 x Fiber Channel
  N5K-M1600      Cisco 6-port 10 Gigabit Ethernet SFP Module 6 x SFP

nexus5596(config-slot)# provision model n2k-n2224TP
nexus5596(config-slot)# exit
nexus5596(config)# sh run int e101/1/1

!Command: show running-config interface Ethernet101/1/1
!Time: Wed Nov  9 17:02:57 2011

version 5.0(3)N2(2a)

interface Ethernet101/1/1


As you can see, after pre-provisioning the FEX with the “slot” and “provision model” commands the interface appears in the configuration (empty interface configuration) and you can start configuring the port.

As a side note, the model list above also includes a FEX that has not yet been officially announced: “N2K-C2248GV+P  Fabric Extender 48x1G 4x10G POE Module”.


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  1. this will be very useful to us. thanks for posting!

  2. Thanks Miguel! Fixed the link.

  3. Not available on N7k ?

  4. Not available on Nexus 7k ?

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