5.2 Given a scenario, troubleshoot common cabling and physical interface issues
Cable Issues
Improper termination
Definition:
Improper termination happens when the ends of a network cable are not connected correctly to the connectors (like RJ-45 for Ethernet cables). This can cause the network to have errors, slow performance, or stop working completely.
Think of it as the cable not being “plugged in correctly,” but more technical: the wires inside are not arranged or connected properly.
1. How Termination Works
Most network cables (like Cat5e, Cat6) have 8 wires inside, arranged in pairs. Each wire carries signals for data transmission. The termination process connects each of these wires to a connector in a specific order.
There are two main standards for arranging these wires in an RJ-45 connector:
- TIA/EIA-568A
- TIA/EIA-568B
Important: Both ends of the cable must follow the same standard for a straight-through cable, or different standards for a crossover cable.
2. Common Types of Improper Termination
- Wrong wire order
- If the wires are not in the correct sequence, data cannot transmit correctly.
- Example: Plugging wires in 1-2-3-4-5-6-7-8 incorrectly can make the network unreliable or fail.
- Loose or unseated wires
- Wires must fully reach the end of the connector and be crimped tightly.
- Loose wires may work intermittently or fail under stress.
- Untwisted pairs too much
- Each pair in a cable is twisted to reduce interference.
- Untwisting too much at the connector end increases crosstalk, causing slow speeds and errors.
- Incorrect connector type
- Using an RJ-45 connector meant for solid wire on stranded wire, or vice versa, can prevent proper contact.
- Damaged cables during termination
- Cutting wires too short or damaging insulation can break the signal path.
3. Symptoms of Improper Termination
Improperly terminated cables can create these real-world network issues:
- Devices cannot connect to the network.
- Slow network speeds or frequent disconnects.
- High error rates in network traffic (seen in network monitoring tools).
- Intermittent connectivity issues that seem random.
- Network devices showing link lights off or flickering.
4. How to Test for Improper Termination
Network technicians often use:
- Cable testers
- Checks each wire in the cable to ensure it is properly connected from end to end.
- Can detect wrong wire order, open circuits, or shorted wires.
- Continuity tests
- Ensures each wire has a complete path through the cable.
- Network performance tests
- Slow speeds or errors may indicate termination issues.
5. How to Fix Improper Termination
- Strip the cable correctly and arrange wires according to TIA/EIA standards.
- Insert wires fully into the RJ-45 connector.
- Use a proper crimping tool to secure the connector.
- Avoid untwisting more than 0.5 inches of the twisted pairs.
- Retest with a cable tester before deployment.
6. Why It’s Important for the Exam
On the CompTIA Network+ exam, you may encounter questions like:
- Identifying network issues caused by improper termination.
- Choosing the correct method to terminate a cable.
- Using tools to test cable connectivity.
Key points to remember for the exam:
- Always follow TIA/EIA standards.
- Twisted pairs must stay twisted until the connector.
- Use the right connector for the cable type.
- Improper termination leads to errors, slow speeds, or no connectivity.
Summary in Simple Terms:
Improper termination is when a cable isn’t connected correctly at its ends. It causes network problems like slow connections, errors, or complete failure. Fixing it involves arranging wires in the correct order, keeping pairs twisted, using the correct connector, and testing the cable.
