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Upgrading Software Images on redundant SUP720 (CAT6509)


We would like to upgrade IOS software image on our Cisco WS-C6509.

We've got redundant Supervisor Engine 720/MSFC3:

5    2  Supervisor Engine 720 (Active)         WS-SUP720-3B       SAL11477LF5

6    2  Supervisor Engine 720 (Hot)            WS-SUP720-3B       SAL11477L4J

The device is operating so we'are creating low impact towards the environment.

We're thinking of using SSO mode but we read that when I reset the standby Supervisor Engine the version mismatch message brings about a reload all modules (Redundancy Mode changes from SSO to RPR).

Is It correct?

Is there another method to upgrade without loosing any data?

Thank you,

Best Regards


Everyone's tags (4)

Upgrading Software Images on redundant SUP720 (CAT6509)

I think you need to reload the chassis because the mismatch between the running one and the standby don't allow to run on redundancy.

VIP Expert

Upgrading Software Images on redundant SUP720 (CAT6509)


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You can reset or force a redundancy switch over for one supervisor.  This is "hitless" but supervisors will no longer be in redundancy.  It usually takes several minutes for inactive supervisor to reload.

When you reset or redundancy switch over the 2nd supervisor, the chassis will go off-line for several minutes.  (Note: switching over to the 2nd supervisor already running different IOS seems to be just a little quicker, but line cards are restarted which is what causes the "hit".)

Hall of Fame Expert

Upgrading Software Images on redundant SUP720 (CAT6509)

Hello Daniele,

depending on the initial SW image and the new SW image the chassis might support in service software upgrade.

read the following chapter from 12.2SX C6500 configuration guide

However, also ISSU is not hitless so you need a maintenance time window.

Hope to help



Upgrading Software Images on redundant SUP720 (CAT6509)


Many thanks for your time and help.

Best Regards


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