Is it correct that when upgrading a major IOS release on a 6509 with dual sup 720's that the chassis blades must be restarted? I was under the impression that it was possible to upgrade without any downtime.
Once image is upgraded on sup720s the are still in flash memory which can either be bootflash or external flash cards. But to make the sup run that image you still have to reload the supervisor engine so that the new upgraded image can be loaded into DRAM.
However if you have dual sups and you have already configured redundancy between them and you follow upgrade procedure you will achieve very les downtime.
Have a look at this link
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I just read the article and it looks like we're down for about 3 minutes. I just now stumbled across and article about ISSU (In Service Software Update) that allows you to do 0 time upgrades but I don't think that we have a recent enough code version to support it. Does anybody have any detail about ISSU and a 6509?