Cisco Catalyst 6880-X VSS ISSU Upgrade Steps

This is a short version without comments and explanations for those that need to get things done quickly without reading through my extensive waffle.

For detailed update procedure with all the explanations check extended article: ISSU Upgrade of Cisco Catalyst 6880-X VSS cluster and its four 6800ia FEX extenders

Let’s start!

1. Get the info on which IOS version is supported to be upgraded with ISSU

Google for ISSU or EFSU IOS upgrade support or use this Cisco doc “SX_SY_EFSU_Compatibility_Matrix1” to select supported IOS for ISSU upgrade from your current version.

2. Upload IOS to both Chassis

copy ftp://admin:[email protected]/c6880x-adventerprisek9-mz.SPA.151-2.SY7.bin bootdisk:

and same for slavebootdisk:

copy ftp://admin:[email protected]/c6880x-adventerprisek9-mz.SPA.151-2.SY7.bin slavebootdisk:

Check if you have this new image on both chassis (dir bootdisk, dir slavebootdisk)

C-6880X#dir bootdisk:
Directory of bootdisk:/

    1  -rw-    33554432  Aug 18 2015 00:11:24 +02:00  sea_console.dat
    2  -rw-   102771080  Aug 18 2015 00:16:36 +02:00  c6880x-adventerprisek9-mz.SPA.151-2.SY4a.bin
    3  -rw-    33554432  Aug 18 2015 00:12:02 +02:00  sea_log.dat
    4  -rw-        8577  Oct 13 2015 11:14:10 +02:00  startup-config.converted_vs
    5  -rw-   102843784  Aug 24 2016 13:36:12 +02:00  c6880x-adventerprisek9-mz.SPA.151-2.SY7.bin

3. Start ISSU Upgrade (issu loadversion)

C-6880X#issu loadversion 1/5 bootdisk:c6880x-adventerprisek9-mz.SPA.151-2.SY7.bin 2/5 slavebootdisk:c6880x-adventerprisek9-mz.SPA.151-2.SY7.bin

3.1. Possible Issue

C-6880X#issu loadversion 1/5 bootdisk:c6880x-adventerprisek9-mz.$
 % CV [ bootdisk:/c6880x-adventerprisek9-mz.SPA.151-2.SY4a.bin ] must be named first in BOOT [ bootdisk: ]

You can check the config of boot system image like this:

C-6880X#sh runn | i boot
 boot system bootdisk:

If you have similar boot system bootdisk: without the image name c6880x-adventerprisek9-mz.SPA.151-2.SY4a.bin or similar in it you should delete that row and enter it with old IOS image mentioned in it:

C-6880X#conf t
Enter configuration commands, one per line. End with CNTL/Z.
C-6880(config)#no boot system bootdisk:
C-6880(config)#no boot system bootdisk:/c6880x-adventerprisek9-mz.SPA.151-2.SY4a.bin
C-6880(config)#do wr
Building configuration...


4. Switchover to upgraded chassis (issu runversion)

C-6880X#issu runversion

With issu runversion we initiate the switchover to upgraded VSS standby chassis. Other chassis, which is still not upgraded, goes into reload and boots with the old IOS image. This is done so that you have the chance to revert to upgrade process and get back to old IOS if something goes wrong with your upgrade.

5. ISSU Upgrade Accept new IOS on upgraded chassis (issu acceptversion)

You need to accept upgraded IOS version on Upgraded standby chassis because if you don’t chassis will assume that something went wrong and it will reboot one more time loading back old IOS version.

C-6880X#issu acceptversion
   % Rollback timer stopped. Please issue the 'issu commitversion' command..

6880 will tell you to execute “issu commitversion” now but don’t do that if you have FEX extenders. They need to be upgraded before “issu commitversion”.

6. Upgrade FEX extenders (issu runversion fex all)

Command can be executed to upgrade all FEX at once (issu runversion fex all) which will bring them all down for about 15-20 minutes. Other option is to initiate upgrade of each FEX separately (issu runversion fex 1) which can be helpful if you have something connected to more that one FEX and it should not experience complete network outage.

C-6880X#issu runversion fex all

With command show issu state you can follow the upgrade procedure and see when all FEX extenders are upgraded. Just wait that FEX_UPGRADE_IN_PROGRESS goes away from all FEX status lines.

C-6880X#show issu state
Slot = 2/5
RP State = Active
ISSU State = Run Version
Boot Variable = bootdisk:c6880x-adventerprisek9-mz.SPA.151-2.SY7.bin,12;bootdisk:/c6880x-adventerprisek9-mz.SPA.151-2.SY4a.bin,12

Slot = 1/5
 RP State = Standby
 ISSU State = Run Version
 Boot Variable = bootdisk:/c6880x-adventerprisek9-mz.SPA.151-2.SY4a.bin,12

This system is Fex-capable
 Fex-ID ISSU Status


When you see something like this:

This system is Fex-capable
 Fex-ID ISSU Status


You can go to the final step of commiting the new IOS version on active chassis.

7. ISSU Upgrade of Standby Chassis (issu commitversion)

C21-03-MER-11-C-6880X#issu commitversion

ISSU commitversion will initiate Standby Chassis reboot. Standby chassis, which is still not upgraded, will boot back up with new IOS image effectively finishing our Upgrade process without none or just few lost pings during this last switchover.

After approximately 12-15 minutes you should see that chassis booted back up and joined VSS cluster which is now running new IOS on all its members.


To verify that you succeeded with the upgrade check the output of:

show issu state detail

show redundancy

show module switch all

They should show both chassis online and joined in VSS cluster with same new IOS image.

For more details and explanation of every step in this document you can read: ISSU Upgrade of Cisco Catalyst 6880-X VSS cluster and its four 6800ia FEX extenders


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