Ethernet UTP Cable Length Limit | Generated by AI
Explanation: Maximum Length of UTP Cable in Ethernet Networks
In Ethernet networking standards (IEEE 802.3), the maximum length for a single segment of UTP (Unshielded Twisted Pair) cable between a node (e.g., computer, station) and a hub/switch is 100 meters. This applies to:
- 10BASE-T (10 Mbps Ethernet)
- 100BASE-TX (100 Mbps Fast Ethernet)
- 1000BASE-T (1 Gbps Gigabit Ethernet, though stricter cable quality is required)
Why 100 Meters?
- Signal Attenuation:
- Electrical signals weaken over distance due to resistance and interference.
- Beyond 100 meters, the signal may degrade, causing errors or connection failures.
- Collision Domain:
- In half-duplex Ethernet (e.g., older hub-based networks), the collision domain must be limited to ensure CSMA/CD (Carrier Sense Multiple Access with Collision Detection) works properly.
- The 100-meter limit ensures that a device can detect collisions before completing the transmission of a frame.
- Standard Compliance:
- The IEEE 802.3 standard specifies 100 meters as the maximum for horizontal cabling (from the workstation to the telecommunications closet).
- This includes 90 meters of solid-core cable (permanent link) + 10 meters of stranded patch cables (for flexibility at both ends).
Key Points
- UTP Cable Types:
- Cat 5e or higher (e.g., Cat 6, Cat 6a) is typically used for 100 Mbps and 1 Gbps Ethernet.
- Lower-quality cables (e.g., Cat 3) may not support 100 meters at higher speeds.
- Exceptions:
- Fiber optic cables can span much longer distances (e.g., 550 meters for multimode, kilometers for single-mode).
- Repeaters or switches can extend the network beyond 100 meters by regenerating the signal.
- Modern Networks:
- Most modern networks use switches (not hubs) and full-duplex communication, which eliminates collision domains but retains the 100-meter limit for UTP.
Summary
The 100-meter rule is a fundamental Ethernet standard to ensure reliable communication. For your question:
- Correct Answer: B (100 meters). ✅
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