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Zorluk: OrtaInterface and Cable Troubleshooting Issues

A network administrator is troubleshooting poor network performance on a switch interface connected to an end host. Executing the `show interfaces GigabitEthernet0/1` command produces the following output:

text
GigabitEthernet0/1 is up, line protocol is up
Hardware is Gigabit Ethernet, address is 0011.bb22.c334 (bia 0011.bb22.c334)
MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Half-duplex, 100Mb/s, media type is 10/100/1000BaseTX
input flow-control is off, output flow-control is off
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:02, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
5 minute input rate 32000 bits/sec, 24 packets/sec
5 minute output rate 98000 bits/sec, 65 packets/sec
521405 packets input, 68102948 bytes, 0 no buffer
Received 410 broadcasts (0 IP multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 0 multicast, 0 pause input
841920 packets output, 110482012 bytes, 0 underruns
2415 output errors, 2415 collisions, 582 late collisions, 0 deferred
0 lost carrier, 0 no carrier, 0 pause output

Based on the CLI output, which of the following is the most likely cause of the interface performance degradation?

  1. A duplex mismatch between the switch port operating in half-duplex and the connected host operating in full-duplex.Cevap
  2. B
    An incorrect Ethernet cable pinout selection (straight-through vs. crossover cable) connecting the two devices.
  3. C
    A native VLAN mismatch on the link causing frame corruption and dropping tagged management traffic.
  4. D
    Misinterpretation of Layer 2 discovery neighbor TLV messages causing duplex auto-negotiation protocol failure.

Cevap

A duplex mismatch between the switch interface operating in half-duplex and the connected end host operating in full-duplex is the primary cause of the late collisions and output errors.
Late collisions occur when a collision is detected after an interface has transmitted the first 64 bytes of a frame. In Ethernet networks, late collisions are most commonly caused by a duplex mismatch (where the local side is set to half-duplex and the remote side is set to full-duplex) or by cable length exceeding standard IEEE specifications. Because the remote full-duplex side does not listen before transmitting, it can send frames while the half-duplex side is mid-transmission, resulting in late collisions on the half-duplex interface.

Adım Adım Çözüm

1
Analyze the operational status and duplex setting from the show interfaces output.
The interface is operating in 'up/up' state at 100Mb/s Half-duplex.
Verifies physical connectivity and operational mode of the local switch interface.
2
Examine the interface error counters.
Output error counters show 2415 output errors, 2415 collisions, and 582 late collisions.
Identifies specific Layer 1/2 error metrics that indicate frame transmission anomalies.
3
Correlate late collision counters with network operational characteristics.
Late collisions occur when a collision is detected after the first 64 bytes (512 bits) of a frame have been transmitted.
Standard collisions are expected in normal half-duplex operation within the slot time, but late collisions strongly indicate a duplex mismatch where one end is configured for full-duplex and sends data regardless of carrier sense.

Anahtar Kavram

Duplex Mismatch Troubleshooting and Collision Counters
Tahmini Süre:1m 30s
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Konular

Interface and Cable Troubleshooting Issues

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