Unit 1: Network Infrastructure
This will allow you to demonstrate your networking skills, knowledge, and abilities, with a focus on enterprise-level switching, routing, and multicast components that support cross-platform (inter)operability and integration with the most recent software-defined technologies.
Errdisable
A function called Errdisable was developed with the purpose of turning off an interface in the event that an error condition is observed on the port that corresponds to it. It is important to note that the port is still enabled in the configuration; nevertheless, the IOS has disabled the port in order to prevent any additional disturbances to the network connection.
The switch’s interface LED will change to ORANGE when a port status becomes Errdisabled.
When you issue a Show interface <interface>, the status will be err-disabled
Causes of Errdisable
Several things can cause a port to become errdisable, including:
- Incorrect GBIC / Small Form-Factor Pluggable (SFP) module or cable
- Address Resolution Protocol (ARP) inspection
- Inline power
- Duplex mismatch
- Port channel misconfiguration
- BPDU guard violation
- Port Aggregation Protocol (PAgP) flap
- Layer 2 Tunneling Protocol (L2TP) guard
- DHCP snooping rate-limit
- UniDirectional Link Detection (UDLD) condition
- Late-collision detection
- Link-flap detection
- Security violation
Reason of Errdisable
When the switch software disables an interface, the switch will send a message to the console notifying it that the port has been disabled. This message will be sent whenever the software disables an interface. Through the use of the following commands, you are able to investigate the causes of errdisabled:
show log
show interface <interface> status err-disabled
Recovery of a port from Errdisable
Prior to regaining access to a port that has been disabled, it is necessary to first address the underlying cause of the issue. The port will be placed back into the err-disabled state by the switch if the problem is not fixed.
