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Catalyst 9300L - Stacking Process


Hi Experts,

Got a project where I'll have to stack 3 cisco Catalyst 9300L. I performed Switch stacking before, but in past projects switches were brand new, with no config at all, where I stack them, configure them, and then deploy them. This time I'll have to do it in 3 switches that are already configured and in production, and here's where I got  a little bit confusing. If I follow the same process of choosing one of them to be the active/primary switch in the stack by setting the priority and other 2 standby,  I guess after connecting the stack cables and power on the switches , the interface configs  and configs in general from switch 1 (active) will be kept , and switches 2 and 3 with inherit configs from switch 1 except by the interface configs, that will have to be redeployed, right ? I need to know what configs will be lost or changed after stacking those 3 switches I can re-configure it later, if necessary.

some relevant information about the switches:

- the 3 switches have the same ios version;

- The 3 switches perform L2 only, no routing

- the 3 switches have the same VLANs' configured and same spanning-tree mode/priority (RSTP, 32768);

- in general, the 3 switches have the same mgmt config (aaa, snmp, line vty) same defaut gateway- the only difference is their management IP


4 Replies 4

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If you looking to add new switch to exiting stack follow below rules (you mentioned some already)

1. Make sure models are compatible when you stacking (Cat 9300L only can be used here)

2. all IOS should be same

3. no config required new device to add in to stack - just change the switch number and priority

4. save config, turn off the device

5. rack the new switch same rack, connect stack and stackpower

6. switch on new switch, and if you have access in master switch connect console and check the logs

7. show switch give you device in stack or not, you will see any errors if not formed stack.

8. then config the ports based on the requirement, what VLAN to be part of ports.

Good reference :


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Thanks for replying @balaji.bandi. The Stack doesnt exist yet, I'll have to create it. I attached the as-is and the to-be pics to give a better context. So as I said they are already configured and in production.

If you check the to-be picture, I'll manipulate the priority value so SW1 will become the primary/active switch. My question is: After I do that, power off switches, connect stack modules and cables, power on them again...switches 2 and 3 will lose interface configs ? I know the slot numbers will change when renumbering the switches, but would switch 2 and 3 keep the interface configs in that scenario?

Ok got you ( i may be missed that bit, thank you for the Clarification)

Question here :

you looking to Build stack with out taking down ? or is the downtime acceptable ? (i prefer to have downtime)

1. i keep the switch as it is with the config. ( just add the switch number 1 and priority 15 (above provided guide help you)

2. Switch 2 - i will make it factory default and upgrade the IOS as same as SW1 or if you get chance upgrade to 17.6.4 latest stable - and switch number 2 and priority 14  - write the config (no other config required)

3. Switch 3 i will make it factory default and upgrade the IOS as same as SW1 or if you get chance upgrade to 17.6.4 latest stable - and switch number 3 and priority 13 - write the config (no other config required)

4. Once the maintenance window agreed.

5. Turn off Switch 1 - connect switch 2 and Switch 3 the stack cables ( as per above mentioned in the guided document)

6. Turn On Switch 1 and Switch 2 and Swtich 3 - do check all all part of stacking - show switch

7. Once you happy with this, configure the switch 2 and switch 3 ports according to the requirement, or before patch layout (as per as -is setup)

8. Write the config

9. now you have both th uplinks on SW1 only if the switch 1 Fails whole access will be lost.

10. Move one of uplink to Swtich 2 (hope you understand this step) with the config

Hope this steps works. let me know any other information required.

Note : i take all are Layer 2, no special config in switch2 and switch3 (as-is in basis)


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It's impossible to do this without a downtime. You will follow the same process you do on non-configured switches and as stated by BB above.

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