什么导致了交换机端口呈现err-disable状态？

导致交换机端口呈现err-disable状态的原因有很多，为方便大家查询，特归纳如下：

 

1. duplex mismatch (A is correct) 2. port-channel misconfiguration 3. Bridge Protocol Data Unit (BPDU) Guard violation 4. UniDirectional Link Detection (UDLD) condition (B is correct) 5. late-collision detection 6. link-flap detection 7. security violation 8. Port Aggregation Protocol (PAgP) flap 9. Layer 2 Tunneling Protocol (L2TP) Guard 10. DHCP snooping rate-limiting 11. EtherChannel guard detects a misconfigured EtherChannel