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Need help to upgrade WLC 9800-CL


Hi Experts , 


We have a cluster of WLC 9800-CL , We are planning to upgrade to 17.3.4c.Could you please share me the good document on upgrade and also suggest the pre and post check which I have to do during the upgrade activity . 




VIP Guru VIP Guru
VIP Guru

what is the current version ? make sure you check the matrix of AP support after upgrade.


read the release notes :


follow steps to upgrade :


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VIP Mentor VIP Mentor
VIP Mentor



  -  For pre and post check  inspect  configuration with the CLI command : show  tech wireless , have the output analyzed by  , please note do not use classical show tech-support (short version) , use the command denoted in green for Wireless Analyzer (for upgrade procedure  check Release Notes and installation guidelines as being mentioned in the document)



So we have to manually upgrade both Active and standby WLC right ... ? Can someone please explain the steps ..Like first which device we have to upgrade and after upgrade do we need to switchover and test the access points? 

@balaji.bandi wrote:

Follow below video : good upgrade steps if you looking issu :

Anyone interested in doing ISSU must make sure they have physical access to the appliances because someone will need to power down the offending unit(s) quickly.

Leo Laohoo
VIP Community Legend VIP Community Legend
VIP Community Legend

@aci_network_test wrote:

Could you please share me the good document on upgrade and also suggest the pre and post check which I have to do during the upgrade activity . 

  1. Do you want to upgrade in GUI or CLI. 
  2. Do you want to upgrade in multiple steps or "one shot"?

safer and better one ....May be GUI ?


 - I advice , CLI : benefits  . 1) you can keep an operator trail (when logging the session) 2) Sometimes in GUI information or errors get cloaked, CLI gives the 'full view' on the updating process.


@aci_network_test wrote:

safer and better one ....May be GUI ?

If GUI, what is the preference: 

  • Multi-step
  • One-shot

Let me explain:  The CLI command to upgrade the IOS-XE of a 9800 is exactly the same for the 9200 and 9500 High-Performance.  The step is convoluted and can be confusing.  

The Cisco "recommended" practice is to perform a multi-step of Install and Activate.  But the most "important" part of the step is the Commit option or the platform will roll-back.  This "recommendation" extremely time consuming and requires three (3) separate commands.  

Personally, I am not a big fan of this option and I prefer to do a one-shot command and this requires ONE (1) command to do the entire lot.  

In the GUI, it is the same thing.  Older firmware (like 17.3.X and earlier) only offers the multi-step upgrade GUI.  On newer firmware (like 17.6.X), the One-Shot GUI upgrade is offered.  

In CLI, both the multi-step and the one-shot upgrade supported in every version.  

Arshad Safrulla
VIP Advocate VIP Advocate
VIP Advocate

You can follow the below document which covers most of the important parts. Please note downgrades are not officially supported by Cisco, so keep a configuration backup before the upgrade. 

Upgrade and Downgrade of Catalyst 9800 Controllers : Tips and Tricks - Cisco


Cisco recommends that you use GUI for the upgrade. Please note that if you are running 16.12.X codes that storage needs to be upgraded from 8GB to 16GB. "From Cisco IOS XE Amsterdam 17.3.1 onwards, Cisco Catalyst 9800-CL Wireless Controller requires 16 GB of disk for new deployments"


If that's the case I recommend to create a new VM with correct compute resources assigned and use the configuration backup to restore your configuration. Please keep in mind some feature behavior might change when you upgrade, so read the release notes carefully and plan it properly.


Arshad Safrulla
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