Understanding Access Point IOS Images

on July 30th, 2013 by Hades | No Comments »

All Cisco Aironet wireless access points and bridges currently being shipped run IOS.  The only exception is the OEAP602.

Note:– Some older Cisco access points did not run IOS, such as the Aironet 340 which ran only VxWorks, and the 1000 series lightweight APs.  Access Point IOS is distributed as a tar file. These tar files can be downloaded from cisco.com SDS; lightweight IOS images (k9w8) are also bundled in the WLC software images (.aes.)  The IOS image names include the following components:-

platform-featureset-tar.version.tar

  • platform- the access point hardware model or family supported by the image
    • ap1g1 – 700 series
    • ap1g2 – 1600 series
    • ap3g2 – 3600/2600 series
    • ap3g1 – 3500/1260 series
    • ap802 – AP embedded in 819, 812, 886VA-W/887VA-W, C88x and C88x routers
    • ap801 – AP embedded in 861W, most 88xW, and 1911W routers
    • c1520 – 1550 and 1520 series mesh APs
    • c1310 – BR1310
    • c1250 – 1250 series APs
    • c1240 – 1240 series APs
    • c1200 – 1200 series (1200/1210/1220/1230)
    • c1140 – 1140 and 1040 series APs
    • c1130 – 1130 series APs
    • c1100 – 1100 series APs (i.e. the AP1121)
    • c520 – 521 AP
    • c350 – 350 series APs
  • featureset- the set of software features supported by the image – one of:
    • k9w7 – autonomous (or “site survey”) IOS
    • k9w8 – full lightweight IOS (this is what is bundled in the WLC .aes image, and is factory installed on “mesh” APs)
    • rcvk9w8 – lightweight recovery image – this is factory installed on lightweight APs, unless a “mesh” image is specified; it lacks radio firmware
    • boot – bootloader image (not IOS) – normally installed by manufacturing and not updated in the field
  • version- the IOS version

Example:

c1240-k9w7-tar.124-25d.JA1.tar

  • Platform: c1240: 1240 series AP
  • Featureset: k9w7: autonomous IOS
  • Version: 124-25d.JA1: 12.4(25d)JA1

 
As AP IOS is always distributed as a tar file, the AP cannot directly execute such a file (thus, if you were to copy c1240-k9w7-tar.124-25d.JA1.tar directly onto AP flash, and then try to boot it, this could not work.)  The tar file contains, in addition to the IOS image proper, the radio firmware files, the HTML GUI files (if present), and various other files.

 

The AP IOS tar file must be unbundled into AP flash using the archive exec command (this is done in an automated fashion when a lightweight AP is upgraded after joining a WLC.)

 

Example:

 

 

After unbundling, the IOS image itself be in a file called flash:/platform-featureset-mx.version/platform-featureset-mx.version – for example, flash:/c1240-k9w7-mx.124-25d.JA1/c1240-k9w7-mx.124-25d.JA1.  The AP is configured to boot this image if the bootloader BOOT environmental variable is set accordingly.

 

To see what IOS image the AP is configured to boot, examine the BOOT variable.

 

Example:

 

AP3502i#more flash:/env_vars | include BOOT

BOOT=flash:/ap3g1-k9w8-mx.152-2.JA/ap3g1-k9w8-mx.152-2.JA

 

To change the BOOT variable, use the IOS config mode boot system command.

 

Example:

 

AP3502i(config)#boot system flash:/ap3g1-k9w8-mx.124-25e.JA2/ap3g1-k9w8-mx.124-25e.JA2