What is a loopback error?
A loopback error occurs when the keepalive packet is looped back to the port that sent the keepalive. The switch sends keepalives out all the interfaces by default.
What is the reason for line protocol down?
The line protocol being down indicates a clocking or framing problem. Probable reasons for this are encapsulation and clock rate mismatches. Ethernet0 is administratively down, line protocol is down: This output indicates that a local interface has been manually shut down using the shutdown command.
How do you fix disabled err?
To recover a port that is in an Errdisable state, manual intervention is required, and the administrator must access the switch and configure the specific port with ‘shutdown’ followed by the ‘no shutdown’ command.
What causes port to go err disabled?
The Errdisable error disable feature was designed to inform the administrator when there is a port problem or error. The reasons a catalyst switch can go into Errdisable mode and shutdown a port are many and include: Duplex Mismatch. Port Security Violation.
What is Loopback Detection?
Loopback Detection (LBD) provides protection against loops by transmitting loop protocol packets out of ports on which loop protection has been enabled. When the switch sends out a loop protocol packet, and then receives the same packet, it shuts down the port that received the packet.
What causes a loopback?
If a network patch cable has both ends inserted into either the same switch or a neighbouring switch that’s part of the same LAN, you can create what’s called a loop back.
What is status up protocol down?
Protocol refers to “Line Protocol”, which is a Cisco way of saying “the connection”. Basically, up/down means the port is available for a cable/connection, but doesn’t have one. Check the cable, or other computer.
What is the reason that the interface status is administratively down line protocol down?
What is the reason that the interface status is “administratively down, line protocol down”? There is no encapsulation type configured. There is a mismatch in encapsulation types. The interface is not receiving any keepalives.
Which command would you use to determine if a port has been error disabled?
When a port is error-disabled, it is effectively shut down and no traffic is being sent or received on that port. The port LED is set to the color orange and when you enter the show port command, the port status shows errdisable.
How do I check my BPDU Guard error?
If BPDU guard is the reason for the errdisable status, check these settings: Verify that the port using portfast is connected to an end station, not to a device that generates Spanning-Tree Protocol (STP) BPDU packets such as switches, bridges, or routers doing bridging.
What causes Bpdu Guard error?
Why does the port get err-disabled due to loopback?
The port gets err-disabled since it is getting its own keep-alive packet looped back to it. Could you please ensure that student is not introducing any physical loop in the room?
Can a bad cable cause the protocol to be down?
It could be a bad cable but it is highly unlikely, usually the interface would be down as well. Generally if only the protocol portion shows as down it is related to configurations that don’t match on the devices that are connected.
How is line protocol down ( Cisco packet tracer )?
Re: Line Protocol is down (Cisco Packet Tracer) If you connected a DCE cable to an interface, then no matter what, that interface must provide clocking and in turn be of type DCE. See the below. Interface Ser0/0/0 is connected to a DCE cable, therefore provides clocking and is defined as type DCE.
What does it mean when a Cisco port is in err disabled?
A port on a Cisco switch may be put into an err-disabled state, which will drop any connections through the switch that are using that port. After logging into the switch you can see if a port is in the err-disabled state by issuing the show interface status command.