adding a new 3750 using a stack cable.

Unanswered Question
Jul 16th, 2009

I have an existing 3750 on the network and want to add another 3750. If I use a stack cable would I just plug it into the new switch and turn it on?

They are both the same model and IOS. From what I read I believe that the switch that has the config would be the primary and the new one would get its config from the primary.

I have this problem too.
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Jason Fraioli Thu, 07/16/2009 - 08:48

That's correct. Go from stack 1 on the existing switch to stack 2 on the new 3750.

You can pre-stage the switch using the "switch" commands, otherwise when you turn on the new switch, you'll need to configure the switchports to reflect your environment.

In other words, the new switch won't automatically inherit any port settings from the master, unless you pre-stage it.

Even if you choose not to pre-stage the new switch, you'll be ok to connect it as you've described.

ekuvinka Thu, 07/16/2009 - 09:54

Thank you Jason.

Another question I have is, If the new switch I'm adding came from a pre-existing stack does that matter?

I noticed how the switch has the interfaces as FastEthernet4/0/1 instead of FastEthernet1/0/1. I have done a wr erase and installed a new IOS and it's still the same.

Rick Morris Thu, 07/16/2009 - 11:40

When you add the switch to existing switch stack it will become a new member of that stack you cabled it into. So it will assume being a member and be configurable as the next inline.

So if this is switch number 2 then it will be fa0/2/0 whereas the master is fa0/1/0

r.robins Thu, 07/16/2009 - 23:37

Also worth noting that the vlan database may differ. This is held in flash with the file vlan.dat. As a precaution I would carry out a write erase, delete the vlan.dat. Ensure that the IOS revision is the same as the current switch and use the "switch" commands to provision the new member in to the stack.

15 minutes work may save you a lot of time later.

Leo Laohoo Fri, 07/17/2009 - 15:57

I've been adding new 3750 switches to an existing stacks and here's some of my "check-list":

1. Make sure the new switch has the same IOS, feature and license as the switch master.

2. (Optional) Specify who is the switch master by envoking the command "switch priority <1-15>. Priority 1 is default but priority 15 means "no election needed and I am the master".

3. Before adding the new switch, I always "provision" the new switch to the stack using the "switch 2 provision " and configure the new ports.

4. Put the stack cable together AND THEN power up the new switch.

Hope this helps.


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