Error Disable

Error-disable can occur from many different ways. Here are various reason that makes interface go to errdisable state.

• 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

When the interface goes into error-disable state, the only way to bring it back up after fixing the issue is to "no shutdown" it. However, there is an IOS command which helps network devices automatically enable the port from err-disable. The command is as followings

R1(config)# errdisable recovery cause ?

 all                                   Enable timer to recover from all error causes
  arp-inspection            Enable timer to recover from arp inspection error disable state
  bpduguard                  Enable timer to recover from BPDU Guard error
  channel-misconfig    Enable timer to recover from channel misconfig error
  dhcp-rate-limit            Enable timer to recover from dhcp-rate-limit error
  dtp-flap                         Enable timer to recover from dtp-flap error
  gbic-invalid                  Enable timer to recover from invalid GBIC error
  inline-power               Enable timer to recover from inline-power error
  l2ptguard                     Enable timer to recover from l2protocol-tunnel error
  link-flap                       Enable timer to recover from link-flap error
  loopback                    Enable timer to recover from loopback error
  mac-limit                    Enable timer to recover from mac limit disable state
  pagp-flap                   Enable timer to recover from pagp-flap error
  port-mode-failure     Enable timer to recover from port mode change failure
  psecure-violation     Enable timer to recover from psecure violation error
  security-violation      Enable timer to recover from 802.1x violation error
  sfp-config-mismatch  Enable timer to recover from SFP config mismatch error
  storm-control            Enable timer to recover from storm-control error
  udld                            Enable timer to recover from udld error
  vmps                          Enable timer to recover from vmps shutdown error

Example 

We configure R1 to automatically re-enable the port if the cause of err-disable was from link flap. We can use following command to accomplish this obejctive.

R1(config)#errdisable recovery cause link-flap

When the event occurs we will see that the router automatically enable the port after specific interval ( in this case, it is default )

Show Logging buffered

Feb  5 20:21:38: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/1, changed state to up

Feb  5 20:21:43: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/1, changed state to down

Feb  5 20:21:52: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/1, changed state to up

Feb  5 20:21:54: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/1, changed state to down

Feb  5 20:22:09: %PM-4-ERR_DISABLE: link-flap error detected on Gi0/1, putting Gi0/1 in err-disable state

Feb  5 20:22:10: %LINK-3-UPDOWN: Interface GigabitEthernet0/1, changed state to down

Feb  5 20:27:09: %PM-4-ERR_RECOVER: Attempting to recover from link-flap err-disable state on Gi0/1

Feb  5 21:41:35: %LINK-3-UPDOWN: Interface GigabitEthernet0/1, changed state to up

Feb  5 21:41:37: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/1, changed state to up