Help with stack cables on 3 switches

[Andy White]

Hi,

I have 2 Cisco 3750 switches stacked using the 2 stack cables, I now need to add a third switch and was going to stack like the below image and wondered does it matter what switch the master switch is as my master is switch A and B and C are members:

Thanks

[francisco_1]

The master is decided on the higher priority. see below for help adding a switch to stack

To add a switch, as a slave, to a stack, complete these steps:

Note: Make sure the switch that you add into the stack has the same IOS version as the switches in the stack. Refer to Catalyst 3750 Software Upgrade in a Stack Configuration with Use of the Command-Line Interface to upgrade the IOS in a catalyst 3750 switch.

1. Change the switch priority of the switch to be added to "1".

   switch stack-member-number priority new-priority-value

   Note: This step is optional, but it will make sure that the switch has fewer chances to become a stackmaster in the future.

2. Power off the switch that is to be added.

3. Make sure that the stack is fully connected so that, when you connect the new switch, the stack will be at least in half connectivity and does not partition.

4. Connect the new switch to the stack with the StackWise ports.

5. Power on the newly added switch.

6. After the new switch comes up, issue the command show switch to verify stack membership.

Tips to add a switch as a Master to the stack

To add a switch, as a master, to a stack, complete these steps:

Note: Make sure the switch you add into the stack has the same IOS version as the switches in the stack. Refer to Catalyst 3750 Software Upgrade in a Stack Configuration with Use of the Command-Line Interface to upgrade the IOS in a catalyst 3750 switch.

1. Issue the show switch command.to get the priority value of the members of the stack.

   3750-Stk>show switch
                                                  Current
   Switch#  Role      Mac Address     Priority     State
   --------------------------------------------------------
    1       Slave     0016.4748.dc80     1         Ready
   *2       Master    0016.9d59.db00     5         Ready

2. Change the priority value of the switch to be added to a value greater than the highest priority of the stack. In the illustration, the priority value has to be a value of more than "5.".

   switch stack-member-number priority new-priority-value

3. Make sure that the stack is fully connected so that, when you connect the new switch, the stack will be at least in half connectivity, and do not partition.

4. With the new switch powered on, connect the StackWise ports of the switch to the stack.

5. The election for the stack master occurs, and the new switch will be elected as the master since it has the highest priority value.

6. The members of the previous stack will reboot themselves to join the new stack. After all the members come up, issue the command show switch to verify stack membership.