Error-disabled state

Q: How deeply does Acing the CCNA Exam: Volume 1 Fundamentals and Protocols cover error-disabled state?

Explains the trigger, down/down status, corrective sequence, and shutdown/no shutdown recovery procedure.

As explained in Acing the CCNA Exam: Volume 1 Fundamentals and Protocols

An error-disabled state is a Cisco switch-port state in which the port is administratively and operationally disabled because of a detected error or protection violation.

An error-disabled state is a Cisco switch-port condition in which a detected error or protection violation makes the port administratively and operationally disabled. With BPDU Guard, receiving a BPDU on a protected PortFast port triggers this state, preventing another switch from affecting the STP topology. section 14.5.2

Recognize and recover the condition:

The port is nonoperational and appears as down/down in show ip interface brief. section 14.5.2
Fix the cause first, such as disconnecting an unintended switch from the PortFast/BPDU Guard-enabled port. section 14.5.2
Reset the port with shutdown followed by no shutdown. section 14.6

BPDU Guard violation

A port intended for an end host receives a BPDU after another switch is connected. Cisco reports that BPDU Guard is disabling the port and placing it in err-disable state. Do not connect switches to PortFast/BPDU Guard-enabled ports in production. section 14.5.2

How Acing the CCNA Exam: Volume 1 Fundamentals and Protocols covers it

Cover of Acing the CCNA Exam: Volume 1 Fundamentals and Protocols

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Also explained in

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Acing the CCNA Exam: Volume 2 Advanced Networking and SecurityAn error-disabled port is a switch port that has been administratively disabled by the device because a configured protection condition was triggered.

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Related concepts

BPDU Guardproduced by · BPDU Guard is a switch-port protection feature that error-disables a port when it receives a Spanning Tree Protocol Bridge Protocol Data Unit.
port securityused by · Port security is a network-switch control that restricts a switch port to authorized device addresses or connection conditions and defines responses to violations.
dynamic arp inspection rate limitingproduced by · Dynamic ARP Inspection rate limiting is a technique that restricts the rate of ARP messages received on a switch port.
ip dhcp snooping limit rate rateproduced by · ip dhcp snooping limit rate rate is a Cisco IOS interface command that configures a DHCP message rate limit in packets per second.

This explainer was generated by Manning's knowledge graph from the text of Acing the CCNA Exam: Volume 1 Fundamentals and Protocols. The section links point to the parts of the book it draws on.