Sem 2 Networking Programming Week 5-1 Data Link Layer

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary function of the Data Link Layer?

To provide routing of packets between networks

To provide error correction and flow control

To encapsulate Layer 3 packets into Layer 2 frames (correct)

To translate domain names to IP addresses

What is the purpose of the Logical Link Control (LLC) sublayer?

To provide media access control

To perform error detection and correction

To manage the flow of data between devices

To communicate between networking software and device hardware (correct)

What is the purpose of the Media Access Control (MAC) sublayer?

To de-encapsulate frames to expose encapsulated packets

To forward frames on the medium of the next network segment

To re-encapsulate packets into new frames

To provide media access control and data encapsulation (correct)

What happens to packets as they travel through multiple data link layers and media transitions?

They undergo de-encapsulation, re-encapsulation, and forwarding Signup and view all the answers

What organization defines data link layer protocols for LANs and MANs?

IEEE Signup and view all the answers

What is the term for the arrangement and relationship of network devices and interconnections?

Network topology Signup and view all the answers

What is the purpose of the data link layer in a WAN environment?

To encapsulate Layer 3 packets into Layer 2 frames Signup and view all the answers

What is the term for a communication system that allows data to be transmitted in both directions, but not simultaneously?

Half-duplex Signup and view all the answers

What is the primary purpose of a physical topology in network description?

To show physical connections and how devices are interconnected Signup and view all the answers

What is the primary function of the header and trailer in a data link frame?

To encapsulate the data and provide control information Signup and view all the answers

Which WAN topology is similar to a star topology?

Hub and spoke Signup and view all the answers

What is a characteristic of point-to-point WAN protocols?

They can be very simple Signup and view all the answers

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

The ability of devices to simultaneously transmit and receive Signup and view all the answers

What type of access control method is used in WLANs and legacy bus topologies with Ethernet hubs?

Contention-based access Signup and view all the answers

What is the typical topology used to interconnect end devices on LANs?

Star or extended star Signup and view all the answers

What is the purpose of the frame start and stop fields in a data link frame?

To identify the beginning and end of the frame Signup and view all the answers

Which of the following is a benefit of a mesh WAN topology?

It provides high availability Signup and view all the answers

What is the main advantage of star and extended star topologies?

They are easy to install and troubleshoot Signup and view all the answers

What is true about nodes in a point-to-point WAN topology?

They may not share the media with other hosts Signup and view all the answers

What type of WAN protocol is used for point-to-point connections?

Point-to-Point Protocol (PPP) Signup and view all the answers

What is the purpose of the addressing field in a data link frame?

To identify the source and destination nodes Signup and view all the answers

What type of LAN topology is used in Ethernet networks?

Ethernet Signup and view all the answers

Study Notes

Network Topologies

Star and extended star topologies are easy to install, scalable, and easy to troubleshoot.

Bus and Ring Topologies

Bus topology: all end systems are chained together and terminated on each end.
Ring topology: each end system is connected to its respective neighbors to form a ring.

Communication Modes

Half-duplex communication: only allows one device to send or receive at a time on a shared medium.
Full-duplex communication: allows both devices to simultaneously transmit and receive on a shared medium.

Access Control Methods

Contention-based access: CSMA/CD and CSMA/CA.
Controlled access: used on WLANs and legacy bus topologies with Ethernet hubs.

Data Link Frame

A data link frame consists of a header, data, and trailer.
The fields of the header and trailer vary according to the data link layer protocol.

Frame Fields

Frame Start and Stop: identify the beginning and end of a frame.
Addressing: indicates source and destination nodes.
Types: identifies the encapsulated Layer 3 protocol.
Control: identifies flow control services.
Data: contains the frame payload.
Error Detection: used to detect transmission errors.

LAN and WAN Frames

LAN and WAN frames use different data link layer protocols, such as Ethernet, 802.11 Wireless, Point-to-Point (PPP), High-Level Data Link Control (HDLC), and Frame-Relay.

Layer 2 Addresses

Also referred to as a physical address.
Contained in the frame header.
Used only for local delivery of a frame on the link.
Updated by each device that forwards the frame.

Data Link Layer

Responsible for communications between end-device network interface cards.
Allows upper layer protocols to access the physical layer media and encapsulates Layer 3 packets into Layer 2 frames.
Performs error detection and rejects corrupt frames.

IEEE 802 LAN/MAN Data Link Sublayers

Consists of two sublayers: Logical Link Control (LLC) and Media Access Control (MAC).
LLC sublayer communicates between networking software and device hardware.
MAC sublayer is responsible for data encapsulation and media access.

Providing Access to Media

Routers perform four basic Layer 2 functions: accepting a frame, de-encapsulating, re-encapsulating, and forwarding.

Data Link Layer Standards

Defined by engineering organizations: IEEE, ITU, ISO, and ANSI.

Physical and Logical Topologies

Physical topology: shows physical connections and interconnections between devices.
Logical topology: identifies virtual connections between devices using device interfaces and IP addressing schemes.

WAN Topologies

Point-to-point: a permanent link between two endpoints.
Hub and spoke: a central site interconnects branch sites through point-to-point links.
Mesh: provides high availability but requires every end system to be connected to every other end system.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz covers different network topologies, including star, extended star, bus, and ring topologies. It explains the characteristics and advantages of each topology.