How to upgrade the software images on redundant Supervisor Engines

[TCC_2]

Resolution

In some scenarios, it is found that the Cisco IOS  on Active and Standby Supervisor does not match hence it affects redundancy.

Catalyst 6500 Series Switches allow a redundant Supervisor Engine to take over if the primary Supervisor Engine fails in order to support fault resistance. The fast software upgrade (FSU) procedure supported by route processor redundancy (RPR) allows you to upgrade the Cisco IOS image on the Supervisor Engines without the need to reload the system.

Refer to the Performing a Fast Software Upgrade section of Configuring RPR and RPR+ Supervisor Engine Redundancy for more information and step-by-step upgrade procedures in Catalyst 6500 Series Switches.

Catalyst 4500 Series Switches allow a redundant Supervisor Engine to take over if the active Supervisor Engine fails. In software, Supervisor Engine redundancy is enabled if you run the redundant Supervisor Engine in RPR or Stateful Switchover (SSO) operating mode.

Refer to the Performing a Software Upgrade section of Configuring Supervisor Engine Redundancy Using RPR and SSO for more information and step-by-step upgrade procedures in Catalyst 4500 Series Switches.

Refer to articleHow to copy the image to the standby bootflash in Catalyst 6000 / 6500 series switches with redundant supervisors for more information on how to copy an image to standby bootflash.

[lluis.hernandez]

According to the document Configuring Supervisor Engine Redundancy Using RPR and SSO for the Catalyst 4500 Series Switches, I understand that switching from SSO redundancy mode to RPR redundancy mode is mandatory before proceeding to an IOS Update (comment to step 9 of the procedure suggests so).

Would then ISSU (which, as far as I know, requires additional feature licensing) be the only way of performing an IOS Update in SSO redundancy mode for the C4500 Series Switches?

Thanks and best regards