Data Link Layer Overview

Front

What is the purpose of the Data Link Layer?

Back

The Data Link Layer prepares network data for the physical network and is responsible for NIC to NIC communications.

Front

What are the main functions of the Data Link Layer?

Back

1. Accepts Layer 3 packets and encapsulates them into Layer 2 frames. 2. Controls how data is placed and received on the media. 3. Exchanges frames between endpoints over the network media. 4. Receives encapsulated Layer 3 packets and directs them to the proper upper-layer protocol. 5. Performs error detection and rejects any corrupt frame.

Front

What are the two sublayers of the Data Link Layer according to IEEE 802 standards?

Back

1. Logical Link Control (LLC) sublayer 2. Media Access Control (MAC) sublayer.

Front

What does the Media Access Control (MAC) sublayer provide?

Back

1. Data encapsulation 2. Addressing for transporting Layer 2 frames 3. Error detection 4. Media access control for multiple devices.

Front

What are the three common physical WAN topologies?

Back

1. Mesh 2. Point-to-point 3. Hub and spoke.

Front

What is the difference between half-duplex and full-duplex communication?

Back

Half-duplex communication allows only one device to send or receive at a time, while full-duplex communication allows both devices to transmit and receive simultaneously.

Front

What is contention-based access in a multiaccess network?

Back

Contention-based access allows two or more end devices to attempt to access the network simultaneously, using methods like CSMA/CD and CSMA/CA.

Front

What is CSMA/CD and where is it used?

Back

Carrier Sense Multiple Access with Collision Detection (CSMA/CD) is used in legacy Ethernet LANs and operates in half-duplex mode.

Front

What is CSMA/CA and where is it used?

Back

Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) is used in IEEE 802.11 WLANs and operates in half-duplex mode.

Front

What are the three parts of a data link frame?

Back

1. Header 2. Data 3. Trailer.