Cabling between Ethernet switches — choose the correct RJ-45 UTP type In a traditional setup without auto-MDI/MDI-X, which twisted-pair cable should be used to directly interconnect two switches at their copper Ethernet ports?

Introduction / Context:
Correct cabling ensures that transmit (TX) pairs on one device land on receive (RX) pairs on the other. Historically, devices of the same type (switch-to-switch, host-to-host) needed crossover cables; different types (host-to-switch) used straight-through cables. Auto-MDI/MDI-X increasingly removes this requirement, but the underlying rule remains important for exams and legacy gear.

Given Data / Assumptions:

• Two Ethernet switches with RJ-45 copper ports.
• No auto-MDI/MDI-X or it is disabled.
• Standard 10/100/1000Base-T pinouts apply.

Concept / Approach:
Same-type devices transmit and receive on the same pin pairs, so a crossover swaps the relevant pairs (1↔3 and 2↔6 on 10/100Base-T). With auto-MDI/MDI-X, either cable often works, but the canonical answer for two switches is the crossover cable.

Step-by-Step Solution:
Identify device types: switch-to-switch (same type).Apply cabling rule: same type → crossover, different type → straight-through.Choose crossover as the correct cable.

Verification / Alternative check:
Check port LEDs and link status after connecting. If auto-MDI/MDI-X is present, straight-through may still link; however, in exam contexts, the expected answer is crossover.

Why Other Options Are Wrong:

• A: Straight-through is for host-to-switch traditionally.
• C/D: CSU/DSU is for WAN serial links, unrelated to Ethernet copper patching.
• E: Rolled cable is for console connections to a serial port, not data links.

Common Pitfalls:
Confusing console rollover with crossover; and assuming auto-MDI/MDI-X applies to all gear—older hardware requires the correct cable type.

Final Answer:
Crossover cable