3750X/3850 Microcode Updates

[cbradt]

I have a number of 3750X and 3850 switches that I  need to upgrade.  I've been surprised in the past with microcode updates that take place at the reboot of the switch.  When working without console access it is a bit alarming when the switch doesn't come back online at all for 30-40 minutes.

How can I determine in advance if a microcode update will take place so that I assess and expect the correct outage period?

[glen.grant]

  Unless you have spare box to test it on you don't really know.  I have never seen the smaller boxes like you are stating take more than say 5-8 minutes to completely boot up .  Even bigger boxes like the 6509's should not take more than say 12 minutes or so .  You had something else going on if it took 30-40 minutes for the switch to be reachable again .  If you have big stacks of 3750's say 8 switches in a stack then it will take somewhat longer .

[cbradt]

Perhaps a minor exaggeration but anywhere from 15 to 25 is not at all uncommon.  In some of those cases I was on the console watching it so I knew it was the microcode.  Hard to believe that there is no way to anticipate this but if that is the case so be it.

Thanks  

[johnd2310]

Hi,

I have seen this on this on the 3750x and 3560x, where upgrades can take 20 minutes or more because of microcode update. The easiest solution is to upgrade the microcode when you upgrade the ios using the archive command. e.g.

archive download-sw /upgrade-ucode  tftp://x.x.x.x/yyyyy.tar

This way you will have less downtime because the microcode is upgrade while switch is running.

thanks

John