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Community Member

Stack on 3750G Question

I have 2 switches running at the moment and I want to plug a 3rd in. Will I lose Network Connectivty with the Master and 2nd switch while it synchronizes with the new 3rd switch? or will it not affect anything ?


Re: Stack on 3750G Question


before adding another switch to the stack please read the following:

Powering Considerations

Managing Switch Stacks

When everything is done correctly to my knowledge user traffic should not be impacted.

Regards, Martin

Community Member

Re: Stack on 3750G Question


Before you add the switch make sure the current master stays master by setting the switch priority.

This can be done with the command:

swich priority 15 (highest numbers possible)

This will make absolutely sure your added switch won't become the master. (it shouldn't but just to be sure)

See as example this switch:

switch#sh switch


Switch# Role Mac Address Priority State


*1 Master 0011.bb26.1d80 3 Ready

2 Slave 0011.bb20.c280 2 Ready

3 Slave 0012.012b.e400 1 Ready

4 Slave 0012.0118.2f80 1 Ready

5 Slave 0012.014a.3300 1 Ready

6 Slave 0013.c35a.c180 1 Ready

7 Slave 0013.8098.a600 1 Ready

Switch one will stay master because it is set to 3.

You also can pre-configure the other switch by means of provisioning with the command:

switch 3 provision ws-c3750g-24t

Ofcourse replace your switch number and type.

When this is done you can allready configure the ports on the switch.

You can turn the synchronisation off but my experience is that you will not loose any connectivty and I have done a lot of these

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