I have a C6504 with dual sup32-pisa's. I need to upgrade the IOS on the sups and want to do the upgrade without any down time. In a test environment I have tried to do the upgrade according to the documentation but I loose connectivity to the switch and the switch disconnects from the network during the process. When I perform the 'hw-module module 2 reset' command the standby sup is loaded with the new IOS just fine but when I perform the 'redundancy force-switchover' command things don't work that well. The switch to the standby sup is performed and the primary sup is reloaded but all the line cards are reset(not standby sup). During the process I loose connectivity(ospf) to the standby sup causing a 2 to 3 minute downtime.
I am trying to upgrade from 12.2(18)ZY2 to 12.2(18)ZYA.
Can you upgrade the IOS without any downtime? If so is there another method to perform the upgrade?