Lecture 02: Basic Concepts of Networking (Part I)

Summary

This lecture delves into fundamental computer networking concepts, contrasting LAN and WAN, and exploring data transfer methods like circuit switching and packet switching. It highlights the efficiency of packet switching for bursty data traffic and introduces virtual circuits as a less dynamic alternative to datagrams, used predominantly in internet communication. The discussion sets the stage for further exploration of networking issues in subsequent lectures.

Takeaways

• 🌐 The script introduces the concept of computer networks as a communication system for various computing devices to connect and communicate over the internet or a network.
• 🔌 The importance of networking is highlighted for better connectivity, communication, resource sharing, and social interaction through applications like social networks.
• 🏢 The script differentiates between Local Area Networks (LAN) and Wide Area Networks (WAN), explaining that LANs connect devices in a smaller geographical area and are faster, while WANs connect devices over larger distances and are slower and more expensive.
• 🚀 The most common standard for LANs mentioned is Ethernet, which has evolved from 10 Mbps to speeds of 100 Gbps and beyond.
• 🌐 The script discusses the two primary methods of data communication over networks: circuit switching and packet switching, with circuit switching being the traditional method and packet switching being more modern and widely used.
• 🔗 Circuit switching establishes a dedicated path for communication, similar to old telephone systems, guaranteeing a fixed bandwidth but can be inefficient due to the continuous reservation of the channel even during idle times.
• 📦 Packet switching breaks down messages into packets, each with a header containing destination information, allowing for shared network resources and better utilization, making it suitable for bursty data traffic.
• 🛑 The script explains the 'store and forward' concept in packet switching, where packets are stored in an intermediate node's buffer and then forwarded to the next link, improving link utilization and allowing for data rate conversion.
• 🗺️ Packet routing in packet switching is done on a per-packet basis using routing tables, which can also accommodate dynamic changes in network conditions, unlike the static routing of virtual circuits.
• 📈 Two approaches to packet transmission are mentioned: virtual circuits and datagrams. Virtual circuits establish a fixed route for all packets of a communication, while datagrams allow for more dynamic and efficient routing.
• 📝 The script concludes by stating that the next lecture will continue the discussion on datagram approach and other networking issues, indicating a deeper dive into these topics.

Q & A

What is the primary purpose of computer networks?

The primary purpose of computer networks is to enable communication between different computing devices, which can be of various types and are connected to the internet or some kind of network, allowing them to exchange data and communicate with each other.

Why are computer networks essential for resource sharing?

Computer networks are essential for resource sharing because they allow for the distribution and utilization of resources such as storage space and computing power over the network, which is particularly evident in cloud computing services.

What are the two main types of computer networks discussed in the script?

The two main types of computer networks discussed are Local Area Networks (LAN) and Wide Area Networks (WAN), with LANs connecting hosts within a small geographical area and WANs connecting devices or networks over larger distances such as cities, countries, or continents.

What is the typical speed range for modern Local Area Networks?

Modern Local Area Networks (LAN) typically operate at speeds ranging from gigabit per second to speeds beyond 100 giga Hertz, with Ethernet being the most commonly used standard.

How do Wide Area Networks differ from Local Area Networks in terms of speed and cost?

Wide Area Networks (WAN) are generally slower than Local Area Networks (LAN) and tend to be more expensive in the long run due to the need for leasing lines from service providers, whereas LANs are typically owned and managed by the users, resulting in lower ongoing costs.

What are the two primary methods of data communication over a network mentioned in the script?

The two primary methods of data communication over a network mentioned are circuit switching and packet switching, with circuit switching being an older method that establishes a dedicated path for communication, and packet switching being a more modern method that shares communication links among multiple transmissions.

What is the main disadvantage of circuit switching when it comes to data transmission efficiency?

The main disadvantage of circuit switching is that it dedicates a channel for the entire duration of communication, which can lead to inefficient use of the channel, especially for bursty data traffic generated by computers where there are periods of high data transmission followed by periods of no data.

What is the basic concept behind packet switching?

The basic concept behind packet switching is that a message is broken up into smaller pieces called packets, each with a header containing destination information. These packets are transmitted separately over a shared network infrastructure, allowing for more efficient use of network resources and better handling of bursty traffic.

What is the store and forward concept in packet switching?

The store and forward concept in packet switching involves temporarily storing incoming packets in an internal buffer at each intermediate node before forwarding them to the next link. This allows for improved link utilization and the handling of varying traffic conditions.

How does packet switching handle the routing of packets?

In packet switching, each packet is independently routed through the network on a per-packet basis, not on a per-message basis. Intermediate nodes use routing tables to decide which outgoing link to forward each packet to, based on the destination address in the packet header.

What are the two approaches to packet transmission mentioned in the script, and which one is predominantly used in the internet?

The two approaches to packet transmission mentioned are virtual circuits and datagrams. The datagram approach is predominantly used in the internet due to its flexibility and efficiency in handling diverse network conditions.