Adding Switch 4 into an existing Cisco StackWise setup.

 Successfully completed the activity of adding Switch 4 into an existing Cisco StackWise setup.

Sharing this update to spread knowledge and help others who work on similar stack expansion tasks.
This included preparing the new switch, setting correct priority, forming the final ring topology, verifying stack health, and validating network services after the change.
ADDING SWITCH 4 INTO EXISTING 3‑SWITCH STACK
With Master / Standby / Member Roles + Correct Priority Command


1. Existing Stack Overview
Switch
Role
Priority
Example Serial Number
Switch 1
Master
15
FOC1234A1AB
Switch 2
Standby
14
FOC1234B2CD
Switch 3
Member
10
FOC1234C3EF


2. Pre‑Checks
Check IOS Version
show version
show switch
Backup Configuration
copy running-config startup-config
Verify Stack Health
show switch
show switch neighbors
show switch stack-ports summary


3. Prepare the New Switch (Switch 4)
Switch 4 must run independently first, then set priority.
Correct command:
switch 4 priority 5
reload
This ensures Switch 4 joins as a Member after stacking.


4. Cabling Plan (Final 4‑Switch Ring)
SW1 P1 --> SW2 P2
SW2 P1 --> SW3 P2
SW3 P1 --> SW4 P2
SW4 P1 --> SW1 P2
This creates a 100% redundant StackWise ring.


5. Power‑On Sequence
Power ON Switch 1 (Master)
Power ON Switch 2 (Standby)
Power ON Switch 3 (Member)
Power ON Switch 4 (New Member)


6. Post‑Change Verification
Check Stack Members
show switch
Expected Example Output:
Switch
Role
Priority
Serial Number
Switch 1
Master
15
FOC1234A1AB
Switch 2
Standby
14
FOC1234B2CD
Switch 3
Member
10
FOC1234C3EF
Switch 4
Member
5
FOC1234D4GH
Check Stack Ports
show switch stack-ports summary
show switch stack-ports errors
Check Neighbors
show switch neighbors


7. Service Validation (Post Testing)
Ping gateway
ping <gateway-ip>
Ping management IP
ping <mgmt-ip>
Check user connectivity
Test application access
Verify internet browsing


8. Rollback Plan
Power off Switch 4
Remove its stack cables
Reconnect original ring between Switch 1‑2‑3
Power ON: Switch 1 --> Switch 2 --> Switch 3
Validate:
show switch