How often should the 6509's and 3750's switches be rebooted?
Does Cisco have a best practice document on this and recommendation how long the switch should be up before it gets rebooted?
Why is a reboot needed if there are no indications of issues on the log?
Not sure if there is a recommended time for how long a switch or router should be up before a reboot. Seen several routers that have been up for more than 2 years.
My recommendation would be to only reboot when needed.
I'd agree with Larry here.
If you're not seeing any issues with your IOS revision and there are no relevant PSIRTs (security notices applicalble to features and or exposure of your device requiring an IOS upgrade) then you can go a very long time without rebooting, if ever.
I'm sure it's far from a record, but our corporate distribution router that supports >1000 downstream devices day in and day out has never been rebooted since installation just over 5 years ago. I have a top of rack Layer 2 switch (2900 series running CatOS) that's almost at 10 years.
That said, you should have some monitoring scheme that assures you everything is healthy. But as long as memory and cpu are happy, the device will run forever.
I had some problem about switches unspected reboot after some time because it had a memory problem or something like that.
Another problem about some switches to not reboot in a periodic time is about patch management. I think if we have one switch working for 2 or 3 years - probably it is vunerable because it never received any update from Cisco or your brand.
Since the device is working properly not causing any problem, I can't find a reason reboot is needed.
I had been running a 3750 core switch on a full production environment for more than 3 years without any particular problem.