FS S3400-48T4SP - Page 7

POE+ SERIES SWITCHES LOOPBACK DETECTION CONFIGURATION GUIDE
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5
loopback-detection vlan-control 1-5
Global Configuration:
loopback-detection
vlan 1-3
Switch S2:
Configure interface GigaEthernet0/1:
switchport mode trunk
Configure interface GigaEthernet0/2:
switchport mode trunk
Configure interface GigaEthernet0/3:
switchport mode trunk
Global Configuration:
vlan1-3
Switch S3:
Configure interface GigaEthernet0/1:
switchport pvid 3
If S3 has loopback and PVID of the port is 3, the packets will forward back to G5/1 of S1. S1 will block G5/1 if there is loopback.