What happens when two different stacks are connnected together?

[mcgiga]

Hi,

what happens when you connect two different stacks (turned off) incorrectly together with stacking cables and then turn both on?

Unfortunately I can‘t test it myself currently and have not found anything on google.

[Joseph W. Doherty]

First there's a stack election for master and winner will be stack's config.

Stack members with differ config than master's may conflict with stack member with same member number or loose their config.

[Flavio Miranda]

@mcgiga 

 It will depend. First we need to understand what do you mean by incorrectly. Usually if you do anything incorrectly it will not work.

In order to work in stack, there will be some requirements that all the switch on the stack must be in compliance . Are they?

If they are not, does not matter if you connect them corrently or not, they will not form a stack.

Now, if you take a stack of switch that was working before and connect to another stack that was working before, you are going to end up having a bigger stack, that´s it.

[mcgiga]

Let‘s say we have stack A and B. Each stack has is‘s own working configuration. All switches are the same modell and firmware version.

Then you connect each stack together but you make the mistake and connect it as if it‘s one big stack together.

[Flavio Miranda · Accepted solution]

If you plugged the right cables in the right place, there will be a new election and it will be formed a new stack.

[mcgiga]

So either config of stack A or B will get lost?

[Flavio Miranda]

It may depend on which switch Will be the master. If one switch from Stack A Win the election, the config from Stack A Will be the config for the whole stack

[mcgiga]

I would have assumed that if a switch already has a different startup configuration, the switch cannot simply be integrated into another stack.

[Flavio Miranda]

Well, of course there Will chance of failing but any Stack need to start somehow, right?

 Ideally, we erase the config and start from Scratch or we use a Brand New device, but, It is not Impossible that an used switch gets in a Stack and successfully Join and accecpt the master config. 

[mcgiga]

Sure that‘s right. I mean kind of a security feature that prevents that as long as there is not default config when it‘s brand new.

I will have a look tomorrow and see how the situation is onsite.

[Flavio Miranda]

let us know