Examkin

Soru

Zorluk: OrtaTroubleshooting VLAN, Trunking, and Switching Issues

A network technician is troubleshooting a performance issue on a newly installed network switch port connected to a high-volume server. Monitoring tools report low overall throughput, a high count of frame check sequence (FCS) errors, and a constantly incrementing late collision counter on the switch port interface. The interface status shows the link is operational at 100 Mbps. Which of the following is the most likely cause of this issue?

  1. A duplex mismatch where one side of the connection is operating in full-duplex mode and the other in half-duplex modeCevap
  2. B
    A native VLAN mismatch across opposing ends of an 802.1Q trunk connection
  3. C
    The absence of a Layer 3 router to forward broadcast traffic between distinct VLANs
  4. D
    An improperly configured Spanning Tree Protocol (STP) priority value set to 61440 on the switch

Cevap

A duplex mismatch where one side of the connection is operating in full-duplex mode and the other in half-duplex mode
The correct answer identifies a duplex mismatch. When one port is configured for full-duplex and the connected port is operating in half-duplex, the full-duplex end sends traffic without performing carrier sensing. The half-duplex end senses a collision mid-transmission, registering late collisions and causing packet corruption that registers as FCS errors.

Adım Adım Çözüm

1
Analyze the physical and Layer 2 error indicators described in the scenario
Identified specific interface symptom indicators: 100 Mbps link speed with late collisions and FCS (Frame Check Sequence) errors
Late collisions occur when a device detects a collision after transmitting the first 64 bytes of a frame, which strongly indicates a timing or mode mismatch in media access control.
2
Evaluate the mechanism causing late collisions
Determined that full-duplex devices send data without checking for carrier sense, while half-duplex devices wait for clear channels and detect collisions during full-duplex transmissions
When auto-negotiation fails or manual configuration is inconsistent, one side defaults to half-duplex and the other to full-duplex, causing late collisions on the half-duplex node and FCS/CRC errors on the full-duplex node.
3
Differentiate from alternative Layer 2 misconfigurations
Ruled out native VLAN mismatches, missing Layer 3 routing, and STP root priority misconfigurations
VLAN and STP misconfigurations affect frame tagging, path forwarding, or spanning-tree topology, but do not produce physical late collision counters.

Anahtar Kavram

Duplex Mismatch Symptoms and Troubleshooting
Tahmini Süre:1m 15s
Bu soruyu puanla

Konular

Troubleshooting VLAN, Trunking, and Switching Issues

Bu konudan daha fazla soru