Remove member of a 3850 stack

[as00001111]

Hey guys,

I want to remove a member of a cisco 3850 stack (in total 3 switches that are stacked together)

They are also power-stacked.

What would be the best approach to do that?

Can I do that live?

[Mark Malone]

Once its not the master its fine , power it down and remove it , if its the master a re-election will reoccur

You can delete all configuration for the switch you removed with...no switch x provision (model)

[as00001111]

Okay, but what do I do with the stack cables and powerstack cables?

Can I do that hotplug?

[Mark Malone]

Yes those cables can be re-arranged and connected live but don't break the stack ring while doing it make sure each switch has at least one stack cable connected to another switch , it also depends on what way its cabled currently but not breaking the stack ring between the switches is the key to do it live , or else do a planned window and shut it all down and re-arrange it

[paul driver]

Hello

The removal of a stacked switch is not as important as its role in the powerstack setup, With this you have to be careful, as you can bring down the whole stack!

The process of removing a stacked switch WITHOUT it being power stack, is basically straight forward.

• Power off switch
• Disconnect the stackwise cabling from that switch
• Issue no switch xxxx provison xxx
• Reconnect remaining stackwise cables to close stack ring

Now with the same switch but it’s ALSO power stacked need to make sure of what stack power mode the stack it currently running.

The default is SHARING mode which doesn’t allow you to have redundancy if a switch fails, it may result in that all POE attached devices in the stack begin shutdown down and the way it does this depends on the LOAD SHEDDING mode selects due to the role the failed or removed switch was performing, And it switch priority in that stack.

The other mode is REDUNDANT mode which does provide resiliency in case of a failed active power stacked switch, this is due to having one switch (usually the highest powered) not to be included in the total power consumption allocation and as such if there is failure or removal of a switch then the attached poe devices can pull it power from this redundant switch.

I would suggest you review this link prior to any removal of stacked powered switch  - here

Due to personal experience and to not being aware of the above I did bring down a whole stack once-
Outch!!  - which I dont wont the repeat!

res
Paul

[as00001111]

That's not good!

My stack is in power sharing.

What happens when I remove the powerstack cables first?

Does this have the same effect?

[paul driver]

Hello
If you remove the power cable then that switch will still get power or try to draw power from the power stack to supply it own Poe devices

What switch priority does it have!
How much power is it supplying?
Is this a remove or replacement!?

If the former I would disconnect it Poe devices first

I would also review it role and switch priority

Res
Paul

[as00001111]

Paul,

I asked what happens if I remove the powerstack cables first, not the power supply cables.

Additionally, there aren't any devices connected to the switch I want to remove.

[paul driver]

Hello
You mean the stackwise cables?
Then you will isolate the switch from the rest of the stack and the switch stack ring bw will half as the stack ring won’t be complete

I guess the power stack would still be valid
Though I have never tested it that way to be totally sure

Res
Paul

[as00001111]

Paul,

I think we talk past each other.

The stackwise cable are supposed to form the data stack.

But I talk about the powerstack cables.

What happens when I remove the powerstack cables (not the data-stack-cables!) from the switch I want to remove?

[paul driver]

Hello
I have indeed stated in my two previous post what would happen regards removal of the stadkwise and power cabling

Regards
Paul