Cisco WLC 7.2 FUS code release

Cisco recently released version 7.2 of their Wireless LAN Controller code. Along with this update came something new for several administrators in the form of an ‘FUS’ update. This update is available for the 5500 , WiSM 2, and the Flex 7500 platforms and contains a variety of firmware specific updates for each platform including:

  • For the 5500 and WiSM2
  • Field Recovery image update
  • Bootloader updates to 1.0.16
  • Offline Field Diagnostics to version 0.9.28
  • USB Console to 2.2
  • MCU image update too 1.8 (5500 only)
  • FPGA update to 1.7 (5500 only)

For the Flex 7500 controllers, there is a RAID firmware update. There is no FUS update for the 2500 controller or any of the legacy platforms (they’re not supported in release 7.2 in general anyway). Buried in the release notes are a variety of nuggets, but it is imperative that this update be installed by itself with a reboot between it and the main 7.2 code release. The order is not important, just the fact that there is a reboot in-between. Additionally, in order for the FUS image to actually update the various components, you need to have a serial attachment to the WLC during the reboot and you must interact with the image upgrades in order for them to execute. This means that if you’re used to doing the ER updates that you just ‘apply and forget’, this is going to be a deviation from that process. To add to this, each update requires you to answer ‘yes’ in order happen but they’re not quick. You will end up burning somewhere south of about a half an hour to pull off a complete upgrade and if you happen to miss one, you’ll have to reupload the image and step through it again. Cisco is nice enough to tell us during the update approximately how long each will take and these numbers are fairly close to what I’ve experienced in the field. The tally on a 5500 is:

Upgrade Bootloader from 1.0.1 to 1.0.16

  • Erasing Flash (estimated 6 seconds)
  • Writing to Flash (estimated 41 seconds)
  • Checking Boot loader integrity (estimated 2 seconds)
  • Total: 49 seconds

Upgrading FPGA from rev 1.3 to rev 1.7

  • Upgrade takes about 75 seconds to complete

Upgrading Env from rev 1.6 to rev 1.8

  • Upgrade takes about 4 seconds to complete

Upgrading USB from rev 1.27 to rev 2.2

  • Upgrade takes about 11 seconds to complete

Upgrade OFD from version WLCNG OFD 0.8.1 to WLCNG OFD 0.9.28

  • Erasing Flash (estimated 24 seconds)
  • Writing to flash (estimated 111 seconds)
  • Total: 135 seconds

Upgrade Field Recovery Image from version to

  • Erasing Flash (estimated 49 seconds)
  • Writing to flash (estimated 716 seconds)
  • Total: 765 seconds

Yes, you read that correctly – the Field Recovery Image takes a whopping 13 minutes to execute! Of interest to those of you that use the USB serial console built into the WLC is the fact that the USB update will flat out break your session. Once you kick off that particular update, you should suspend you session and wait for it to complete. The kicker of course is that you won’t know since you don’t have a console session. The lesson here is that while it is possible to perform these updates using the USB console, you’ll not regret preferring the good old fashioned RJ-45 console cable method.

If you happen to miss an update and have to reapply the image, you’ll notice that the FUS image will proactively check to see if the updates have been applied already:


Checking for Bootloader upgrade

Bootloader upgrade …

Bootloader 1.0.16 is up to date.


Checking for FPGA upgrade

FPGA upgrade …

FPGA image is up to date

It will perform this check for all components, but when it gets to the Field Recovery Image, it will actually ask you if you want to re-apply it:

Field Recovery Image upgrade …

        Field recovery image Current version is up-to-date.

        Answer “y” below will force upgrade to run again.

        Are you sure you want to proceed (y/N) ? n

Again, note that if you re-apply this particular update, you’re in for a thrilling 13 minutes of ‘edge of your seat’ thrills while it completes. There is no way to cancel it and as you’re warned numerous times throughout the FUS process in bad english:

      * Lost POWER will completely kill this unit and not recoverable. *

      * There may be multiple reboot. Please let the program run.      *

Once you’ve completed your updates, and you’re observing the production image boot, it will verbosely tell you what the version of all of these components are so you can tell that they’ve been successfully applied or not:

Cisco AireOS Version

Firmware Version FPGA 1.7, Env 1.6, USB console 2.2

Initializing OS Services: ok

Applying these updates is important and does resolve a variety of issues so it is recommended to go through whatever outage window you’re going to require to apply them or you may want to consider pulling a spare (+1) controller out of service, upgrading it and moving all of your Access Points over to free up your primary for upgrade. Either way, you should do this – just make sure the updates actually apply!

3 Responses to Cisco WLC 7.2 FUS code release

  1. John says:

    It seems this is just FPGA updates, and doesn’t really require you to upgrade to 7.2. Do you know if you can run 7.0.x with the 7.2 FUS?

    • scwifi says:

      You can indeed run the FUS 7.2 with the WLC release 7.0 code. Infact, you will be running in this state if you apply the FUS before the main release with a reboot in-between as advised by Cisco.

  2. Todd says:

    I ran this on two WLC’s last night. One of them worked fine and another did everything but I noticed the field recovery image was still

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