Late Collisions on a Half-Duplex Link: Troubleshooting and Causes

Late Collisions on a Half-Duplex Link

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Question

An engineer notices some late collisions on a half-duplex link.

The engineer verifies that the devices on both ends of the connection are configured for half duplex.

Which of the following is the MOST likely cause of this issue?

Answers

Explanations

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A. B. C. D.

C.

Late collisions occur when a transmitting device detects that another transmission is occurring on the network while it is still transmitting. This is a problem because collisions can cause data loss, reduce network performance, and increase network congestion.

In a half-duplex network, only one device can transmit at a time, while the other device is in receive mode. When both devices are transmitting simultaneously, a collision occurs, causing the transmitting devices to stop transmitting and retry at a later time.

Given that the devices on both ends of the connection are configured for half-duplex, the most likely cause of the late collisions is that one of the devices is transmitting before it has finished receiving. This could happen if one of the devices has a misconfiguration, such as a network interface card (NIC) that is set to full-duplex instead of half-duplex. This misconfiguration causes the device to transmit and receive at the same time, which results in collisions.

Other possible causes of late collisions include improperly terminated links, excessive cable lengths, or hardware issues. Improper termination can cause signal reflections, which can interfere with the transmission and cause collisions. Excessive cable lengths can cause signal degradation and delay, which can also result in collisions. Hardware issues, such as faulty NICs or cables, can cause transmission errors, including late collisions.

However, given the information provided in the question, a misconfigured device is the most likely cause of the late collisions on a half-duplex link.