DCN UNIT 1 "Network Edge, End Systems, Access Networks, Routers, Network Core, High-Speed Switches, Routers, Optical Fiber Links, Network Servers, Network Losses, Processing Delay, Queuing Delay, Transmission Delay, Propagation Delay, Switching, Circuit Switching, Packet Switching, Computer Network, Network Classification, Geographical Area, Network Topology, Network Protocol, Network Architecture, Transmission Media, Twisted Pair Cable, Coaxial Cable, Fiber Optic Cable, Wireless Media, Layered Architecture, TCP/IP Protocol Suite, Application Layer, Transport Layer, Internet Layer, Network Interface Layer, OSI Model, Physical Layer, Data Link Layer, Network Layer, Transport Layer, Session Layer, Presentation Layer, Application Layer

Data Communication and Networking - Unit 1

1. What do you mean by Network Edge? Explain the functionality of various constituents of Network Edge?

The Network Edge refers to the point at which devices such as computers, smartphones, and other client devices connect to the network. It is the boundary where the end-user equipment interfaces with the network infrastructure. The primary constituents of the Network Edge include:

• End Systems: These are the devices used by end-users to access the network, such as computers, smartphones, and tablets. They are responsible for generating and consuming data.
• Access Networks: These are the physical and logical connections that link end systems to the first router in the network. They include wired connections (like Ethernet) and wireless connections (like Wi-Fi).
• Routers: Devices that forward data packets between computer networks. At the edge, they route traffic to and from the end systems and the core of the network.

2. What do you mean by Network Core? Explain the functionality of various constituents of Network Core?

The Network Core is the central part of a telecommunications network that provides various services to the customers connected to the network. The core's primary function is to route data packets across the network efficiently. The key constituents of the Network Core include:

• High-Speed Switches and Routers: These devices manage the data traffic between different segments of the network, ensuring data packets are forwarded to their correct destination.
• Optical Fiber Links: These provide high-speed data transmission capabilities using light signals, which are essential for handling the large volumes of data traffic in the core.
• Network Servers: Servers that provide various services such as data storage, processing, and network management functions.

3. How do Network losses and delays occur? What are the different types of Network delays? Explain.

Network losses and delays occur due to various factors within a network. Losses typically happen when packets are dropped due to network congestion, while delays can occur due to several reasons. The types of network delays include:

• Processing Delay: The time taken by routers and switches to process packet headers and determine the forwarding path.
• Queuing Delay: The time packets spend waiting in queue at the router or switch due to congestion before they can be forwarded.
• Transmission Delay: The time taken to push all the packet's bits onto the wire, calculated as the packet length divided by the transmission rate of the link.
• Propagation Delay: The time it takes for a signal to travel from the sender to the receiver, which depends on the physical medium and the distance between nodes.

4. What do you mean by Switching? Explain i. Circuit Switching ii. Packet Switching

Switching refers to the method by which data is directed through a network from the sender to the receiver. There are two primary types of switching:

1. Circuit Switching: A dedicated communication path is established between two devices for the duration of the communication session. This path remains reserved exclusively for the session, providing consistent and predictable performance. Examples include traditional telephone networks.
2. Packet Switching: Data is broken into packets, each of which is transmitted independently through the network. Packets can take different paths to reach the destination, where they are reassembled. This method is used in modern networks, such as the Internet, as it is more efficient and flexible.

5. What is Computer Network? What is the basis of Network Classification? Explain

A Computer Network is a group of interconnected devices that can share resources and information. These networks enable communication and resource sharing between devices, facilitating data exchange and collaboration. Networks can be classified based on several criteria:

• Geographical Area: Such as Local Area Network (LAN), Wide Area Network (WAN), and Metropolitan Area Network (MAN).
• Network Topology: The physical or logical layout of the network, including star, bus, ring, and mesh topologies.
• Network Protocol: The rules and conventions for data exchange, such as TCP/IP, Ethernet, and ATM.
• Network Architecture: The design and structure of the network, including client-server and peer-to-peer architectures.

6. What are the various types of Transmission media in use? Explain each with advantages and disadvantages

Transmission media refers to the physical pathways that connect devices in a network. The main types of transmission media include:

• Twisted Pair Cable: Consists of pairs of wires twisted together. It is inexpensive and widely used for telephone and Ethernet networks, but it is susceptible to electromagnetic interference and has limited bandwidth.
• Coaxial Cable: A single conductor surrounded by a shield. It offers better shielding from interference compared to twisted pair, suitable for cable TV and broadband Internet, but it is bulkier and more expensive.
• Fiber Optic Cable: Uses light signals to transmit data. It provides high bandwidth and is immune to electromagnetic interference, ideal for long-distance and high-speed communication. However, it is expensive and more difficult to install and maintain.
• Wireless Media: Uses radio waves or infrared signals. It offers mobility and ease of installation, suitable for Wi-Fi and mobile networks, but it can be affected by interference and has security concerns.

7. What is the layered architecture of Network Model? Explain i. TCP/IP Protocol Suite ii. The OSI Model

The layered architecture of network models organizes communication functions into a series of layers, each building upon the functions of the previous one. The two most prominent models are:

1. TCP/IP Protocol Suite: The protocol suite used for the Internet, structured into four layers:
   • Application Layer: Provides protocols for specific data communication services on a network, such as HTTP, FTP, and SMTP.
   • Transport Layer: Ensures reliable data transfer with protocols like TCP and UDP.
   • Internet Layer: Handles the movement of packets around the network using IP addressing and routing.
   • Network Interface Layer: Manages the physical transmission of data over a network medium.
2. OSI Model: A seven-layer model developed by the ISO to standardize network communication:
   • Physical Layer: Transmits raw bit streams over a physical medium.
   • Data Link Layer: Provides node-to-node data transfer and error correction.
   • Network Layer: Manages data routing and forwarding between devices across multiple networks.
   • Transport Layer: Ensures complete data transfer and error recovery.
   • Session Layer: Manages sessions between applications.
   • Presentation Layer: Translates data between the application layer and the network format, including encryption and compression.
   • Application Layer: Provides network services directly to applications.