To minimize network outages, you can download an upgrade image to the access point from the controller without resetting the
access point or losing network connectivity. Previously, you would download an upgrade image to the controller and reset it,
which causes the access point to go into discovery mode. After the access point discovers the controller with the new image,
the access point downloads the new image, resets, goes into discovery mode, and rejoins the controller.
You can now download the upgrade image to the controller and then download the image to the access point while the network
is still operational. You can also schedule a reboot of the controller and access points, either after a specified amount
of time or at a specific date and time. When both devices are up, the access point discovers and rejoins the controller.
Concurrent Controller to AP Image Upgrade
This table lists the controllers and their maximum concurrent AP image download support.
Controller
|
Maximum Number of Concurrent AP Image Download Supported
|
Cisco 5520 Wireless Controller
|
1000
|
Cisco 8540 Wireless Controller
|
1000
|
Cisco vWLC
|
1000
|
Flash Memory Requirements on Access Points
This table lists the Cisco AP models and the minimum amount of free flash memory required for the predownload process to work:
Cisco AP
|
Minimum Free Flash Memory Required
|
3700(I/E)
|
16 MB
|
2700(I/E)
|
16 MB
|
1700(I/E)
|
16 MB
|
 Note |
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The required flash memory can vary based on the radio type and the number of antennas used.
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During the predownloading of image to APs, some APs do not have enough memory to keep the current radio firmware available.
After the image has been predownloaded, these APs have the image only on flash memory and no other memory is available to
host the current image or version radio firmware. The APs that have this limitation are as follows: Cisco Aironet 700, 1520,
1530, 1550, 1600, 3500, and 3600 Series APs.
For more information about this limitation, see CSCvg41698.
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As part of the fix for CSCvb75682, if the flash memory of Cisco Aironet 1700, 2700, and 3700 Series APs is less than 10 Mb and a recovery image is present,
the backup images in these APs are deleted.
|