1.4 Interface and Cable Issues Flashcards
Recognize interface and cable issues, such collisions, errors, mismatch duplex, and/or speed. (15 cards)
What is a duplex mismatch?
A condition where devices use different duplex settings.
A duplex mismatch occurs when one device is set to full duplex and the other to half duplex, leading to errors, retransmissions, and poor performance due to collisions and data loss.
Define:
collisions
Interference when two devices transmit at the same time.
Collisions happen in half-duplex Ethernet networks, causing packet loss and requiring retransmissions.
True or False:
Duplex mismatches only occur when both devices are set to full duplex.
False
Duplex mismatches happen when one device uses full duplex and the other uses half duplex, leading to issues like collisions.
What are common signs of a duplex mismatch?
- Slow network performance
- Increased collisions
- Late collisions
- Retransmissions
These signs happen due to improper communication between devices using different duplex settings, leading to inefficient data transmission.
Fill in the blank:
A half-duplex device will likely experience ________ in a duplex mismatch.
collisions
Half-duplex devices need to take turns transmitting, increasing the chance of collisions when paired with a full-duplex device.
What does the term late collision refer to?
A collision occurring after the first 64 bytes of a frame.
Late collisions usually indicate a duplex mismatch, where one side is set to full duplex and the other to half duplex, causing collisions after data has started transmitting.
A network interface shows frequent input errors. What is the likely cause?
Cable issues or physical layer problems.
Input errors can result from faulty or damaged cables, poor connections, or interference, and can also be a sign of a duplex mismatch or incorrect cabling.
What does a runts error counter indicate?
Frames smaller than 64 bytes.
Runts often occur due to collisions or misconfigurations, resulting in small fragments of data that don’t meet the minimum size requirement.
Define:
speed mismatch
A situation where two devices on a network link differ in speed.
Speed mismatches cause transmission errors because devices cannot sync their communication rates, leading to packet loss or slow performance.
What are the effects of a speed mismatch?
Intermittent connectivity and slow speeds.
A speed mismatch causes devices to fail to synchronize their transmission rates, resulting in communication errors and delays.
What can cause a notconnect state in an interface?
- No cable
- Bad cable
- Wrong cable pinouts with MDIX disabled
- Speed mismatch
- Neighboring device issues (powered off, shutdown, or error disabled)
If the cable is damaged, not properly seated, or incompatible, the interface may fail to establish a link, resulting in a “notconnect” state.
True or False:
A notconnect state can occur if a cable is too long.
True
Ethernet cables that exceed the maximum length limit (typically 100 meters for Cat 5e or Cat 6) may result in a “notconnect” state due to signal degradation.
Fill in the blank:
The counter that tracks received frames with errors is the ____ ____ counter.
CRC error
The CRC error counter indicates frames that fail the Frame Check Sequence (FCS) due to transmission problems, such as collisions or physical layer issues.
How can you troubleshoot an interface showing high CRC errors?
- Check for faulty cables or connectors.
- Ensure proper cable standards (e.g., no cross-talk or twisted pair issues).
- Verify correct speed and duplex settings.
CRC errors often point to physical layer issues, such as bad cables, electrical interference, or incorrect configuration of duplex or speed settings.
True or False:
Autonegotiation prevents duplex and speed mismatches.
True
Autonegotiation allows devices to automatically match duplex and speed settings, preventing mismatches that can cause performance issues.
