Upgrade procedure for multiple WLCs without N+1

Answered Question
Jan 25th, 2012
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Hello, I would like to discuss another method of a bulk controller upgrade and see what other engineers take on this upgrade path would be.


Say I have an instance of 8 4404s with 50 APs each, In this case I have N+1 redundancy where I can follow the normal proceedure

Normal Proceedure

  1. Move all APs to controllers 1-4
  2. Preload all APs with the new code version
  3. Upgrade and reboot empty controllers 5-8  to new code version
  4. Move all APs to 5-8 with new code versoin
  5. Upgrade empty 1-4
  6. Move all APs back home



Now take the same scenario only chage it to 80 APs per controller. I've now lost my N+1 and cannot do it quite as smoothly.

As opposed to trying to follow the normal proceedure and have an extended window of "brown outs" How about doing it all at once.

Black-out accelerated proceedure:

  1. Preload new code on all controllers
  2. Preload new image on all APs on all controllers
  3. Reboot all 8 controllers at the same time.
  4. Allow time for APs to connect back and load the new image


I assume with this proceedure that I might see around 15-30 minutes of actual downtime to the site but it seems like that could be preferable to two-three hours of brown outs.


What are your thoughts, and do you feel that 15-30 minutes is

Correct Answer by George Stefanick about 5 years 2 months ago

Michael,


Welcome to CSC!


I have 40+ WLCs and like you looked at this very closely. In my environment I do a predowload and reboot them all. Ive tried the surgical approach and in my case if you get aps bouncing back and forth on WLCs they will upgrade then downgrade etc.


Also note -- If you are on 7.0.98.0 code, predownload "may" have a bug. I noticed an issue during a recent upgrade in mu network and later someone commented about the same issue here on CSC.

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Stephen Rodriguez Wed, 01/25/2012 - 14:57
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if you do the pre-download to the AP, then you would have like 5 minutes, while the AP and the WLC reboot.


But prior to the 5508, the 4404 could upgrade 10 AP at a time.  So the formula went:


(ap/10 * 3) +5 = upgrade time, per controller.  Sof if you couldn't pre-download you would be looking at like 30 minutes.


If you can predownload, you only have to deal with the reboot time.



Steve

George Stefanick Wed, 01/25/2012 - 16:02
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Steve congrats on the red star !

Stephen Rodriguez Wed, 01/25/2012 - 16:14
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@george thanks man! Lot of work to catch up with you, Scott and Leo


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Correct Answer
George Stefanick Wed, 01/25/2012 - 16:01
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Michael,


Welcome to CSC!


I have 40+ WLCs and like you looked at this very closely. In my environment I do a predowload and reboot them all. Ive tried the surgical approach and in my case if you get aps bouncing back and forth on WLCs they will upgrade then downgrade etc.


Also note -- If you are on 7.0.98.0 code, predownload "may" have a bug. I noticed an issue during a recent upgrade in mu network and later someone commented about the same issue here on CSC.

Michael Burk Wed, 01/25/2012 - 22:53
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Thank you all for the good advice. I'm going from 6.0.202.0 to 7.0.116.0


The site in question is 24/7 and very concerned with uptime so I think I'm going to just require them to purchase some 5508s and reach N+1. Or I will just install some extra 4404s. Either way it's nice to know that I have the option of the black out upgrade. It seems alot more reliable with the N+1.

Leo Laohoo Wed, 01/25/2012 - 23:06
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If you had HREAP the WAPs it wouldn've been better.  When the controllers reboot, the WAPs operate normally.

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