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Difficulty: HardNetwork Cable Types and Connectors

A field technician is deploying a custom twisted-pair Ethernet patch cable to connect two older Layer 2 switches that do not support Auto-MDIX. The technician terminates End 1 using the T568A standard. On End 2, the technician arranges the wire positions as follows: Pin 1 (White/Green), Pin 2 (Green), Pin 3 (White/Orange), Pin 4 (Blue), Pin 5 (White/Blue), Pin 6 (Orange), Pin 7 (White/Brown), and Pin 8 (Brown). After plugging in the cable, the link LEDs on both switch ports remain unlit. Which of the following pinout modifications must the technician make to End 2 to resolve the issue and establish link connectivity?

  1. Swap the position of the White/Green and Green wires (pins 1 and 2) with the White/Orange and Orange wires (pins 3 and 6).Answer
  2. B
    Swap the position of the Blue and White/Blue wires (pins 4 and 5) with the White/Brown and Brown wires (pins 7 and 8).
  3. C
    Reverse all eight wire positions on End 2 completely so that Pin 1 becomes Pin 8 and Pin 2 becomes Pin 7.
  4. D
    Swap each solid-colored wire with its corresponding striped wire across all four twisted pairs on End 2.

Answer

Swap the position of the White/Green and Green wires (pins 1 and 2) with the White/Orange and Orange wires (pins 3 and 6) on End 2.
To connect two legacy switches that lack Auto-MDIX support, a crossover cable is required. A crossover cable has T568A pinout on one end and T568B pinout on the other. In this scenario, End 1 was terminated using T568A, but End 2 was also wired using T568A (White/Green on pins 1/2, White/Orange on pins 3/6), producing a straight-through cable. Swapping the White/Green and Green wires (pins 1 and 2) with the White/Orange and Orange wires (pins 3 and 6) reconfigures End 2 into the T568B standard, successfully establishing the crossover transmit/receive path.

Step-by-Step Solution

1
Analyze the existing cable wiring and symptom.
End 1 is T568A and End 2 is also currently wired as T568A (1: W/G, 2: G, 3: W/O, 6: O), which creates a straight-through cable.
Connecting two like devices (switch-to-switch) without Auto-MDIX support using a straight-through cable connects transmit pins to transmit pins, failing to establish link.
2
Identify the requirement for a crossover cable.
A crossover cable requires T568A on one end and T568B on the opposite end.
Converting one end to T568B maps transmit pins (1 and 2) on one side to receive pins (3 and 6) on the other side.
3
Determine the necessary wire swap to transform T568A to T568B on End 2.
Swap pair 2 (Orange: pins 3 and 6 in T568A) with pair 3 (Green: pins 1 and 2 in T568A).
This reconfigures End 2 to T568B (1: W/O, 2: O, 3: W/G, 6: G) while leaving pins 4, 5, 7, and 8 in their standard locations.

Key Concept

Ethernet Crossover Cable Pinout (T568A vs T568B)
Estimated Time:2m 0s
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Topics

Network Cable Types and Connectors

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