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Zorluk: KolayTroubleshooting VLAN, Trunking, and Switching Issues

A network technician notices severe network performance degradation on a workstation connected to a switch port. Checking the switch port statistics shows a high count of late collisions and alignment errors, while the workstation's network interface card is manually set to full-duplex. Which of the following is the most likely cause of this issue?

  1. The switch interface is operating in half-duplex mode, causing a duplex mismatch.Cevap
  2. B
    The native VLAN configured on the switch port does not match the workstation's default VLAN.
  3. C
    The workstation is assigned to a different VLAN than its default gateway without inter-VLAN routing.
  4. D
    The switch port has Spanning Tree Protocol enabled with an incorrect root bridge priority.

Cevap

The switch interface is operating in half-duplex mode, causing a duplex mismatch.
A duplex mismatch occurs when one end of an Ethernet link runs in full-duplex mode and the other operates in half-duplex mode. The half-duplex port senses collisions while the full-duplex port transmits arbitrarily, resulting in late collisions, FCS errors, and poor throughput.

Adım Adım Çözüm

1
Analyze the reported port symptoms and interface error counters.
The presence of late collisions specifically indicates that one side of the link is attempting CSMA/CD collision detection (half-duplex) while the other side transmits simultaneously without checking for carrier sense (full-duplex).
Late collisions occur when a collision is detected after the first 64 bytes of a frame have been transmitted, which is characteristic of a duplex mismatch.
2
Evaluate the configuration state of both link endpoints.
Since the workstation is hardcoded to full-duplex, the switch port autonegotiation likely failed or was manually set to half-duplex.
Duplex autonegotiation standard specifies that if autonegotiation fails on one end, the port defaults to half-duplex mode.

Anahtar Kavram

Duplex Mismatch Identification
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Konular

Troubleshooting VLAN, Trunking, and Switching Issues

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