Ethernet Basics and Collision Avoidance

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Questions and Answers

What does full-duplex communication allow hosts to do?

Transmitting and receiving simultaneously. (correct)

Transmit data only.

Transmitting in one direction at a time.

Receive data only.

What occurs when two hosts transmit frames at the same time on a shared medium?

One of the frames is prioritized and sent.

A collision occurs. (correct)

Data is successfully transmitted.

Both frames are discarded without notification.

What action is taken by hosts after detecting a collision?

They send a 32-bit jam sequence. (correct)

They immediately resend their frames.

They stop all transmissions.

They ignore the collision.

How long do hosts wait after a collision before resending their frames?

A random amount of time. Signup and view all the answers

What defines the minimum Ethernet frame size in relation to slot time?

The slot time does define the minimum Ethernet frame size. Signup and view all the answers

What is a characteristic of a collision detected after the slot time?

It is termed a late collision. Signup and view all the answers

What was the slot time defined for 10 and 100Mbps Ethernet?

512 bits. Signup and view all the answers

What must occur for CSMA/CD to function reliably?

Hosts detect a collision before transmitting. Signup and view all the answers

Which authentication method was specifically developed by Cisco and is supported by WPA/WPA2 as an 802.1X authentication method?

LEAP Signup and view all the answers

What is the most common type of Ethernet cable used for networking?

Twisted-pair cable Signup and view all the answers

Which type of twisted-pair cable is characterized by having six twists per inch?

Cat6 Signup and view all the answers

What type of fiber optic cable is designed to allow only a single ray of light to travel across it?

Singlemode fiber Signup and view all the answers

Which connector is specifically used to connect devices to twisted-pair cable?

RJ45 connector Signup and view all the answers

When two hosts transmit a frame simultaneously in a half-duplex connection, what is the result?

A collision will occur Signup and view all the answers

What is the primary purpose of the backoff timer process in Ethernet communications?

To reduce the likelihood of another collision Signup and view all the answers

What is the role of the consistent slot time in Ethernet networks?

To ensure proper functioning of CSMA/CD Signup and view all the answers

What is the primary function of Layer-1 hubs?

Physically connect network devices Signup and view all the answers

What type of Ethernet operation do hubs operate at?

Half-duplex Signup and view all the answers

What is the purpose of the backoff timer process in Ethernet?

To reduce the likelihood of another collision Signup and view all the answers

How does Ethernet control media access on a half-duplex connection?

By utilizing Carrier Sense Multiple Access with Collision Detect (CSMA/CD) Signup and view all the answers

What is a collision domain?

A physical segment where a collision can occur Signup and view all the answers

What is the minimum slot time for 10 and 100Mbps Ethernet?

512 bits, or 64 bytes Signup and view all the answers

How do hubs handle frame forwarding?

Forward frames to all ports except the originating port Signup and view all the answers

What is the purpose of the 32-bit jam sequence sent by hosts after a collision?

To ensure all transmitting hosts are aware of the collision Signup and view all the answers

Study Notes

Ethernet Basics

Ethernet was originally designed for shared media environments.
Full-Duplex communication allows simultaneous sending and receiving of data.
Half-Duplex communication allows only one host to transmit or receive at a time.
Ethernet uses Carrier Sense Multiple Access with Collision Detect (CSMA/CD) for half-duplex connections.
Simultaneous transmissions on a shared medium result in collisions.
Hosts send a 32-bit jam sequence to signal a collision.
Collided frames cannot be processed by receiving hosts.
After a collision, hosts wait a random amount of time before retransmitting.
CSMA/CD relies on detecting collisions before frame transmission completion.

Slot Time and Collision Avoidance

The slot time is the time it takes for a signal to travel the maximum network length and back.
A collision occurring after the slot time is considered a late collision.
The slot time limits the physical length of an Ethernet network.
10 and 100 Mbps Ethernet have a slot time of 512 bits.
Gigabit Ethernet has a different slot time.
The slot time defines the minimum Ethernet frame size.

Authentication Methods

Lightweight Extensible Authentication Protocol (LEAP) uses username/password authentication.
Extensible Authentication Protocol - Flexible Authentication via Secure Tunneling (EAP-FAST) is a Cisco-developed authentication method supported by WPA/WPA2 under 802.1X.
Protected Extensible Authentication Protocol (PEAP) and Extensible Authentication Protocol - Transport Layer Security (EAP-TLS) are also 802.1X authentication methods.

Ethernet Cabling

Twisted-pair cable is the most common Ethernet cable type.
Category 3 (Cat3) cable has six twists per inch.
Single-mode fiber optic cable allows only one light ray to travel.
RJ45 connectors connect devices to twisted-pair cables.
Vampire taps connect devices to thicknet cable.
Cat6 cable offers the highest resistance to external electromagnetic interference (EMI).
Fiber optic cable uses light to transmit signals.

CSMA/CD and Collision Handling

CSMA/CD controls media access in Ethernet.
Collisions occur when two hosts transmit frames simultaneously on a half-duplex connection.
The 32-bit jam sequence alerts all transmitting hosts about a collision.
The backoff timer reduces the likelihood of further collisions.
The slot time ensures proper functioning of CSMA/CD.
10 and 100 Mbps Ethernet have a minimum slot time of 512 bits.

Ethernet Hubs

Hubs are Layer-1 devices that physically connect network devices.
They operate at half-duplex.
Hubs handle frame forwarding by broadcasting frames to all ports except the originating port.
A collision domain is a physical segment where collisions can occur.

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Description

Explore the fundamentals of Ethernet, including full-duplex and half-duplex communication methods. Learn about the crucial role of CSMA/CD in managing network collisions and the significance of slot time in Ethernet networks. This quiz will test your understanding of how data transmission works in shared media environments.