Switches in operation in 3850 stack configuration

[JUNHOLEE95720]

Hello.

I'm using three 3850 Stack units.

We're going to use an additional 3850 this time.

1. I will need the Stack Data cable and the Stack Power Cable recabling. Do I have to turn off the power and work on the old switch as well as the new one? Or is it OK to keep the old switch running?

2. The new switch you are trying to add is in use as a trunk connection because the stack cable hasn't arrived yet.
When I try to construct a stack, is it recommended that I fully reset and connect these configs? Or is it okay to try it as it is?

Is there anything else I need to be extra careful about?

Thank you.Switches in operation in 3850 stack configuration

[balaji.bandi · Accepted solution]

1. I will need the Stack Data cable and the Stack Power Cable recabling. Do I have to turn off the power and work on the old

switch as well as the new one? Or is it OK to keep the old switch running?

BB- No not required to turn off old switch, while the switch running, you can add new switch to stack member

make sure all the IOS are same as running one, make new switch number next to running one , with stack switch priority.

2. The new switch you are trying to add is in use as a trunk connection because the stack cable hasn't arrived yet.
When I try to construct a stack, is it recommended that I fully reset and connect these configs? Or is it okay to try it as it is?

BB - yes configure new switch qas standalone  and connect to old witch as trunk - yes reset the config and follow above mentioned steps to join to MAster stack as stack member

Good stacking document  for reference here :

https://community.cisco.com/t5/networking-documents/how-to-form-a-catalyst-3850-data-stack-and-power-stack/ta-p/3156083

[JUNHOLEE95720]

Changes to Switch Stack Membership

If you replace a stack member with an identical model, the new switch functions with exactly the same configuration as the replaced switch, assuming that the new switch (referred to as the provisioned switch) is using the same member number as the replaced switch.

The operation of the switch stack continues uninterrupted during membership changes unless you remove the active switch or you add powered-on standalone switches or switch stacks.

• Adding powered-on switches (merging) causes all switches to reload and elect a new active switch from among themselves. The newly elected active switch retains its role and configuration. All other switches retain their stack member numbers and use the stack configuration of the newly elected active switch.

  Note	In Cisco IOS XE 3.6.4E and later versions, when a new switch is powered-on as a standalone switch before it is added as part of the switch stack, only this switch is reloaded and not the whole switch stack.

Thank you for your answer.

Based on the above information,
If I add a stack member as I told you, will the existing switches reboot? It is unlikely to happen, but the reference to NOTE would suggest that it could happen because it is not after 3.6.4E version.

What's right?

[balaji.bandi]

ased on the above information,
If I add a stack member as I told you, will the existing switches reboot? It is unlikely to happen, but the reference to NOTE would suggest that it could happen because it is not after 3.6.4E version.

What's right?

As per my experience, the exiting Live Switch act as Master and it will not reboot. the new switch join as slave or member depends on the switches in the stack already.

If you doing the first time, take some additional measures ( and do it in maintenance window)

[JUNHOLEE95720]

Hi

Thank you so much for the answer.

Finally, I want to ask you something.

1. Set the same OS and installation mode

2. Enter Provision 4 command on Master switch
3. The new switch is set to Priority 1 with the Renumber 4 command and then powered off.
4. Mounted in the rack, Stack Cable Stack Power Cable Connection then Power On

Can I do it in this order?

Thank you!

[paul driver · Accepted solution]

Hello

Just like to say the 3850 can be in two kinds of boot mode - Install - Bundle (installpreferred ) and they are incompatible with each other - so if you try to attach a new switch to an exiting stack and the boot modes differ then it will fail to join unless you have the auto upgrade feature active on the stack otherwise you need to make sure of this boot mode prior to attaching the new switch and you can do that by

show version

If then the boot mode is different then you need to change it prior to it joining the new stack

The procedure to change from bundle to install can be found on Cisco web site which will basically tell you to expand the bin file of the iOS and then change the boot system variable to boot from the conf file 

I have limited access to the internet at present  to post the actual url link but I’m sure you should be able to find it.