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Zorluk: ZorNetwork Cable Types and Connectors

A network technician is terminating custom Category 6 Ethernet cables for a office deployment connected to a Gigabit switch. Wire map testing on a newly terminated run reveals that pins 1, 2, 3, and 6 have continuous continuity on both ends matching the T568B standard, but pins 4, 5, 7, and 8 fail continuity completely due to damaged internal conductors. Which of the following network behavior symptoms will the connected workstation experience?

  1. The workstation will successfully establish a network connection, but auto-negotiate at a maximum speed of 100 Mbps.Cevap
  2. B
    The workstation will experience total link failure and report a 'Network Cable Unplugged' status.
  3. C
    The workstation will connect at 1 Gbps speed but exhibit severe packet loss caused by excessive near-end crosstalk (NEXT).
  4. D
    The workstation will assign itself an APIPA address because DHCP discovery packets cannot travel across pins 1, 2, 3, and 6.

Cevap

The workstation will successfully establish a network connection, but auto-negotiate at a maximum speed of 100 Mbps.
100BASE-TX (Fast Ethernet) operates strictly using two pair channels: pins 1 and 2 (transmit) and pins 3 and 6 (receive). Gigabit Ethernet (1000BASE-T) requires all four pairs (pins 1-8). When pins 4, 5, 7, and 8 fail continuity while pins 1, 2, 3, and 6 remain intact, Ethernet auto-negotiation falls back to the maximum operational standard supported by the physical wiring, resulting in a stable 100 Mbps link.

Adım Adım Çözüm

1
Analyze physical pin continuity requirements for Ethernet standards
Pins 1, 2, 3, and 6 correspond to Pair 2 (Orange/Orange-White) and Pair 3 (Green/Green-White) in T568B pinout, which are the required transmit and receive pairs for 10BASE-T and 100BASE-TX standards.
Fast Ethernet (100 Mbps) only uses two pairs (pins 1, 2, 3, 6) for data transmission.
2
Analyze Gigabit Ethernet (1000BASE-T) pair requirements
1000BASE-T requires all four twisted pairs (pins 1 through 8) for full-duplex gigabit transmission.
Without continuous signals across pins 4, 5, 7, and 8 (Pair 1 and Pair 4), the physical layer interface cannot complete gigabit signaling initialization.
3
Evaluate auto-negotiation response to partial physical layer failure
Network interfaces on both ends fall back during link negotiation to the highest mutually supported standard that the physical medium can support, which is 100 Mbps.
Ethernet controllers degrade gracefully to 100BASE-TX when only pairs 1/2 and 3/6 are verified.

Anahtar Kavram

Twisted-Pair Ethernet Pair Usage and Auto-Negotiation
Tahmini Süre:2m 0s
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Network Cable Types and Connectors

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