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3850 Boot Mode


So I ran into an interesting problem the other day. It was my first install of a pair of 3850's stacked together. If you've read other posts you know that I always format flash and put whatever IOS I need on there. So I formated flash and FTP'd cat3k_caa-universalk9.SPA.03.02.02.SE.150-1.EX2.bin to flash. I rebooted the stack and everything was fine. I like to reboot them a couple of times as I configure just to make sure everything is cool, part of the burn-in process. My second reboot only booted to rommon. I was able to boot the switches using the boot [ios image] command. Weird. I know of the bug that was in the earlier release, but I looked it up just to make sure it was fixedin 3.2.2 which it was. After the boot I noticed an "error"

The System is using a non-recommended Boot mode.

Not all features may be available in this boot mode.

Please check the product configuration guide.

After watching another reboot I saw that the switch was trying to load flash:packages.conf. After some more digging I found that you can expand the IOS-XE image to separate the pkg files.


Directory of flash:/

15490  -rwx   223734376  Jul 29 2013 11:50:23 +00:00  cat3k_caa-universalk9.SPA.03.02.02.SE.150-1.EX2.bin

15497  -rwx     2097152  Jul 29 2013 12:22:18 +00:00  nvram_config

1621966848 bytes total (1393471488 bytes free)

Switch#expand file flash:cat3k_caa-universalk9.SPA.03.02.02.SE.150-1.EX2.bin

Preparing expand operation ...

[1]: Expanding bundle flash:cat3k_caa-universalk9.SPA.03.02.02.SE.150-1.EX2.bin

[1]: Copying package files

[1]: Package files copied

[1]: Finished expanding bundle flash:cat3k_caa-universalk9.SPA.03.02.02.SE.150-1.EX2.bin


Directory of flash:/

15490  -rwx   223734376  Jul 29 2013 11:50:23 +00:00  cat3k_caa-universalk9.SPA.03.02.02.SE.150-1.EX2.bin

15497  -rwx     2097152  Jul 29 2013 12:22:18 +00:00  nvram_config

23235  -rw-    74369252  Jul 29 2013 12:23:35 +00:00  cat3k_caa-base.SPA.03.02.02.SE.pkg

23236  -rw-     5808828  Jul 29 2013 12:23:43 +00:00  cat3k_caa-drivers.SPA.03.02.02.SE.pkg

23237  -rw-    32488292  Jul 29 2013 12:23:37 +00:00  cat3k_caa-infra.SPA.03.02.02.SE.pkg

23238  -rw-    30403764  Jul 29 2013 12:23:39 +00:00  cat3k_caa-iosd-universalk9.SPA.150-1.EX2.pkg

46466  -rw-    16079584  Jul 29 2013 12:23:38 +00:00  cat3k_caa-platform.SPA.03.02.02.SE.pkg

46467  -rw-    64580300  Jul 29 2013 12:23:43 +00:00  cat3k_caa-wcm.SPA.

23234  -rw-        1224  Jul 29 2013 12:23:56 +00:00  packages.conf

1621966848 bytes total (1169473536 bytes free)

Switch(config)#no boot system switch all flash:cat3k_caa-universalk9.SPA.03.02.02.SE.150-1.EX2.bin        

Switch(config)#boot system switch all flash:packages.conf

After expanding the pkg files the reboots are working flawlessly. I found there are some caveats to the boot structure:

Installed Boot Mode

You can boot your switch in installed mode by booting the software package provisioning file that resides in


switch: boot flash:packages.conf

The provisioning file contains a list of software packages to boot, mount, and run.

Bundle Boot Mode

You can boot your switch in bundle boot mode by booting the bundle (.bin) file:


boot flash:cat3850-universalk9.SSA.03.08.83.EMD.150-8.83.EMD.bin

The provisioning file contained in a bundle is used to decide which packages to boot, mount, and run. Packages

are extracted from the bundle and copied to RAM. The ISO file system in each package is mounted to the

root file system. Unlike install boot mode, additional memory that is equivalent to the size of the bundle is used when booting

in bundle mode.

I've always installed ASR's in Bundle Boot Mode and never had a problem but it appears as of right now it's not working working or suggested on the 3850's


Excellent write-up. I just had to do this on several 3650's. The command is slightly different, but end result is the same.