The link below discusses err-disabled ports.
http://www.cisco.com/c/en/us/support/docs/lan-switching/spanning-tree-protocol/69980-errdisable-recovery.html
Info below is from Cisco doc:
"There are various reasons for the interface to go into errdisable. The reason can be:
Duplex mismatch
Port channel misconfiguration
BPDU guard violation
UniDirectional Link Detection (UDLD) condition
Late-collision detection
Link-flap detection
Security violation
Port Aggregation Protocol (PAgP) flap
Layer 2 Tunneling Protocol (L2TP) guard
DHCP snooping rate-limit
Incorrect GBIC / Small Form-Factor Pluggable (SFP) module or cable
Address Resolution Protocol (ARP) inspection
Inline power
show interfaces status err-disabled—Shows which local ports are involved in the errdisabled state.
show etherchannel summary—Shows the current status of the EtherChannel.
show errdisable recovery—Shows the time period after which the interfaces are enabled for errdisable conditions.
show errdisable detect—Shows the reason for the errdisable status."
Hope this helps,
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Thanks.
