• 01/28/2013
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How to Set Up Cisco Nexus Fabric Extender

Cisco Nexus Fabric Extenders (FEXs) provide ToR connectivity for Nexus 5000 and 7000 series switches. This 9-step plan shows you how to bring a FEX online, and includes configuration tips and code examples.

5. Power up the FEX. Connect the power cables. Ensure that the redundant power supplies are uplinked to two different power sources.

6. Review console messages. With the FEX powering up, you should see console messages scrolling by on the 5Ks that indicate a FEX has been discovered, ports are coming up (and probably going back down, then back up) and so on.

The first time the FEX boots, it will probably require a firmware upgrade. The Nexus switches to which the FEX is uplinked will upgrade the firmware automatically. The upgrade takes about 10 to 15 minutes. When this process is complete, the FEX will be online and ready for you to document and sanity check.

7. Set the FEX description. This should be simply the name of the FEX. This name shows up in other CLI output, and is helpful in determining just which FEX you're working on.

fex 101
 description FEX-01

8. Verify the FEX is uplinked and ready for use. Here are some commands to help you verify the FEX is uplinked correctly:

(click image for larger view)
Fabric Extender

9. Provision the FEX access ports. Once the FEX is up and running to your satisfaction, you can provision the access ports according to your procedures. I ensure that all new ports are disabled and described as "AVAILABLE". This makes it easy for operators to see what ports can be used when required, and prevents server admins from plugging into a port at random.

Concluding Thoughts

Note that on dual-homed FEXs, the FEX-related configuration commands on the Nexus switches must be identical. You can do this manually by configuring each switch in turn. Cisco also offers a configuration synchronization service to perform this task automatically, but setting up that service is beyond the scope of this article.

While the output of “show fex detail” shows that all FEX access ports are mapped to the virtual port channel, it is possible to map specific access ports to specific uplink ports using static-pinning.

Finally, Cisco offers a Nexus 5K/2K access layer design guide. I recommend you read it carefully to understand the options and caveats when deploying a Nexus infrastructure.

For more instruction on the Cisco Nexus, see How to Configure Cisco Nexus 5500 Virtual Port Channel

Ethan Banks is CCIE #20655, a host of the Packet Pushers podcast, and IT practitioner since 1995. He can be reached at @ecbanks.

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