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ASR9XX Rommon Upgrade


IOS upgrade on asr9xx mandates rommon upgrades sometimes while they can be optional at other times. You may land up in unwanted situation if proper procedure is not followed during upgrades.


This article will include complete details about rommon upgrades on asr9xx platforms b/w different IOS-XE releases


  • Old method of upgrading rommon  (Before 17.3.x) -


1. Check the RSP bootup ROMMON region (ROM0 or ROM1). The example, shows the RSP boots up from ROM0 region



System Bootstrap, Version 15.2(1r)S1, RELEASE SOFTWARE (fc1)
Technical Support:
Copyright (c) 2011 by cisco Systems, Inc.
Compiled Wed 07-Dec-11 07:33 by tinhuang
Current image running: Boot ROM0

2.Copy the ROMMON image to the bootflash on the active and standby RSP.


copy tftp://<path>/rsp2_15_6_18r_s_rommon.pkg bootflash:


3.Use the "upgrade rom-monitor filename bootflash:rsp2_15_6_18r_s_rommon.pkg R0" command to upgrade the version.

Note - R0 represents RSP in slot0 of the chassis. Step 3 upgrades the ROMMON region of the RSP that is not used (ROM1 region) as ROM 0 region is used (in this procedure) in Step 1 to boot up the RSP.


4. Reload the router.


5. Repeat Step 3 to Step 5 to update the other region on the RSP (ROM0) region in this procedure.

Note - We recommend that both region ROM0 andROM1 are upgraded.


Above mentioned steps will upgrade both the rommon regions on a single RSP. For upgrading dual RSP system follwing procedure can be utilized to minimize impact - 


  • Upgrade both the rommon regions on standby RSP (say R1)
  • Perform RPFO 
  • Upgrade both the rommon regions on (new standby) previous active RSP (say R0)



You can minimize downtime by upgrading only one region of rommon with currently running IOS on the router and reloading router with new (target) IOS. Second rommon region can be upgraded on new IOS and required router reload can be done any time later during a planned/unplanned MW. 


CCO doc for rommon upgrade -


  • Auto rommon upgrade - New method of upgrading rommon  (17.3.2 and beyond) -


  •        ISSU Based Upgrades - 


1. Starting 17.3.1 Primary rommon region gets automatically upgraded during IOS upgrade .however secondary region still needs to be upgraded manually (via procedure mentioned in old method above) …reload for the second region can be done later anytime (i.e. as part of any other MW)


2. Starting 17.4.1 ..both the rommon regions will automatically get upgraded with IOS upgrade when needed. User does not have to worry about upgrading rommon at all. 


Minimum required rommon version for auto rommon upgrade functionality to work is 33r. If the current rommon version on any device is lower than 33r then it will have to be first manually upgraded to 33r.


Note - If you are running an old IOS (prior to 16.11.1) having rommon version < 33r and would like to to software upgrade to 17.3.1 and beyond via ISSU then you will need to do step ISSU upgrade in two steps- 

               i) ISSU upgrade to 16.9.6 or 16.12.5

               ii) ISSU upgrade to 17.3.1 and beyond.


Note - For ASR920 upgrades please look at the following software advisory -



  • Non- ISSU Upgrades (Simplest)


1. Extract target image (17.3.2 and above) to bootflash:Image (Both RSP0 & RSP1)

2. Update boot system parameter to point to bootflash:Image/packages.conf in the running-config.

3. Reload