stacking 3850 24t

[Predrag]

Hello guys, 

I have to make stack of two switches 3850 24t. I have one switch in the production and I want to add another one. 
First switch, the one in production is:

1 32    WS-C3850-24T       03.03.00SE        cat3k_caa-universalk9 INSTALL

cisco WS-C3850-24T (MIPS) processor with 4194304K bytes of physical memory.
Processor board ID FOC1752U03B
15 Virtual Ethernet interfaces
28 Gigabit Ethernet interfaces
4 Ten Gigabit Ethernet interfaces
2048K bytes of non-volatile configuration memory.
4194304K bytes of physical memory.
250456K bytes of Crash Files at crashinfo:.
1609272K bytes of Flash at flash:.

License Level: Ipbase

and new one is:

1 32    WS-C3850-24T       16.3.5b           CAT3K_CAA-UNIVERSALK9 INSTALL

cisco WS-C3850-24T (MIPS) processor (revision AC0) with 865070K/6147K bytes of memory.
Processor board ID FCW2202D0X2
1 Virtual Ethernet interface
28 Gigabit Ethernet interfaces
4 Ten Gigabit Ethernet interfaces
2048K bytes of non-volatile configuration memory.
4194304K bytes of physical memory.
250456K bytes of Crash Files at crashinfo:.
1609272K bytes of Flash at flash:.

echnology-package Technology-package
Current Type Next reboot
------------------------------------------------------------------
ipbasek9 Permanent ipbasek9

I will first update production switch to 16.3.5b  and than connect second switch and THAN turn it on.

I would like your opinion, should I manually update ios or will they sync automatically. And for what I should prepare my self. I will download ios of production switch to my laptop and save config, is that good enough and what is worst case scenario that I can expect.

P.S. Diffrence between ipbase and ipbasek9 is there any? 

Thanks. 

[Reza Sharifi · Accepted solution]

Hi,

Before you do anything, first make sure you have a good copy of your config in case something goes wrong during the upgrade.

Make sure the new switch has the exact IOS before adding it to the stack as the IOS will not sync from one switch to another. Only the config will sync from one switch to another.

The 3850 series comes with a USB port. You can simply load the IOS onto it and then copy from usb to flash, set the booth variable and reboot.  Remember if you are doing this in production, there will be downtime until the switch reboots. Do the same thing before adding the second switch to the stack.

Now, once the IOS is the same for both switches, make sure the productions switch (master) has higher priority and also prevision the new switch and give it a lower priority. Turn off the new switch, add the stacking cable and then turn on the new switch. It should come up as a member switch.

Diffrence between ipbase and ipbasek9 is there any

ipbasek9 support security features like SSH and the other one does not.

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3850/software/release/3se/ha_stack_manager/configuration_guide/b_hastck_3se_3850_cg/b_hastck_3se_3850_cg_chapter_010.html

HTH

[Predrag]

Hello Reza,

Thanks for quick reply. I will do it on weekend that was the plan. First I am going to download to usb current ios of production switch and save config. than upgrade ios to 16.3.5b and set priority to 15, new switches comes with priority 1 I think.
I've red this link this morning, but they don't say what can go wrong :)

So if I do it like this am safe?
(I will have backup ios and config and if something goes wrong at least I can set it to beginning state?

Thanks again.

[Reza Sharifi]

Hi,

It's very hard to tell and to know for sure at 100% everything is going to go fine and Cisco or their documentation will not say that.  With upgrades, you never know what can go wrong add that is why you need a good copy of the config and also a maintenance window to do this. If the new switch's priority is the default (1) than it should come up as a member. Also, make sure that both switches have the same license level. You can view that with sh ver and/or "sh license right-to-use" command. Don't forget to prevision the new switch in the existing production switch. 

Also, as you noted, you can always go back to the old IOS if something goes wrong with the upgrade.

Good Luck!

[Joseph W. Doherty]

"Diffrence between ipbase and ipbasek9 is there any?"

K9 support crypto stuff.

"I would like your opinion, should I manually update ios or will they sync automatically."

". . . what is worst case scenario that I can expect."

You end up with an expensive boat anchor. (Generally unlikely.) Saving a copy of IOS and config, other than on the switch, is good, in fact, would recommend it at all times. (Saving license stuff, if possible. elsewhere is good too.)

I've no experience with the 3650/3850, but with the prior 3750s, I always felt insuring devices to be added to a stack had the same IOS version, avoided any auto update issues. I would lean that way for the newer switches too unless I knew the auto upgrade was pretty much flawless.