Introduction to Computer Networking

Introduction to Computer Networking

• The text provides an introduction to computer networking.
• The slides are freely available for use by instructors, students, and readers.
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• The slides are in PowerPoint format, allowing for customization, including animations, and modifications.

Internet Overview

• The Internet is a network of networks consisting of interconnected ISPs.
• Protocols are used to govern the sending and receiving of messages.
• Examples of protocols include TCP, IP, HTTP, Skype, and 802.11.
• Standards, such as RFCs (Request for Comments) and IETF (Internet Engineering Task Force), define the protocols and their use.

Network Structure

• The network edge includes hosts (clients and servers), often located in data centers.
• Access networks consist of physical media such as wired or wireless communication links.
• The network core is made up of interconnected routers and forms a network of networks.

Access Networks and Physical Media

• Residential, institutional, and company networks use various access technologies.
• DSL (Digital Subscriber Line) uses existing telephone lines to transmit data.
• Cable networks use frequency division multiplexing (FDM) to share transmission bandwidth.
• HFC (Hybrid Fiber Coax) combines fiber optic cable and coaxial cable for improved performance.
• Home networks often combine wireless access points with wired Ethernet for flexibility.
• Enterprise networks (Ethernet) typically use Ethernet switches to connect devices within companies or universities.
• Wireless networks use base stations or access points for connection via radio waves.

What are Protocols?

• Protocols define the format and order of messages sent and received among network entities.
• Protocols also define the actions taken when a message is sent or received.
• Everyday examples of human protocols include greetings, conversations, or schedules.

Packet Transmission Analysis

• Hosts send data in packets for transmission.
• Packets are broken into smaller chunks called packets.
• Packets are transmitted at a specific transmission rate, also known as bandwidth.
• Transmission delay is the time needed to transmit a packet into a link based on the link capacity (R) and the length of the packet (L). The delay is calculated as the length of the packet divided by the transmission rate.
• Propagation delay is the time the signal takes to travel across a link which is based on the length of the link and the speed of propagation in the medium.

Types of Delay

• Transmission delay is the time to transmit all bits of a packet on a link.
• Propagation delay is the time for a bit to travel from source to destination of a link.
• Processing delay is the time required to process headers and determine output links in a router.
• Queuing delay is the time a packet waits at a router's output link, waiting for transmission.
• Overall nodal delay is calculated as the sum of transmission, propagation, processing, and queuing delay.

Packet Loss Analysis

• Packets are dropped when the queue in a router's buffer is full.
• Routers drop packets when the arrival rate of packets exceeds the link capacity.

Internet Delays and Routes

• Traceroute is a program that measures the delay between two points on the internet.
• Traceroute sends packets to various routers that reflect back to determine the path.

Throughput

• A throughput is the rate at which bits are transferred between sender and receiver.
• Instantaneous throughput is the rate at a given point in time.
• Average throughput is the rate over a longer period.
• The bottleneck link will constrain the throughput of the network path.