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• Computer networks involve the study of network introductions.

Course Objectives

• The primary goal is to understand modern network architectures from both design and performance perspectives.
• Course work includes clarifying network terminology.
• There is an opportunity to work with network programming using TCP/IP.
• The course exposes students to emerging technologies and their potential impact.

Internet Overview

• The Internet consists of billions of connected computing devices, often referred to as "devices."
• Hosts are end systems running network applications at the Internet's edge.
• Packet switches forward packets, which are chunks of data, using routers and switches.
• Communication links include fiber, copper, radio, and satellite, with transmission rate measured as bandwidth.
• Networks are collections of devices, routers, and links managed by an organization.
• "Fun" Internet-connected devices include Amazon Echo, internet refrigerators, security cameras, IP picture frames, etc.
• Internet standards are the set of protocols used to control the sending and receiving of messages.
• Protocols are everywhere, for example, HTTP (Web), streaming video, Skype, TCP, IP, WiFi, 4/5G and Ethernet.
• Internet standards include RFCs (Request for Comments) and the IETF (Internet Engineering Task Force).

Network Definitions and Classification

• Preliminary definitions and network terminology are important.
• Understanding sample application paradigms is important
• Classification can occur by transmission technology, size/scale, and topology.
• A computer network by Tanenbaum’s definition is a collection of autonomous computers interconnected by a single technology.
• LG&W define a communications network as a set of equipment and facilities that provide a service.
• In a distributed system, a collection of independent computers appears to users as one coherent system.

Client-Server and Peer-to-Peer Applications

• Client-server applications involve a network and a server, where clients request services from the server.
• The client-server model involves requests and replies between client and server machines through a network.
• Peer-to-peer systems do not have fixed clients or servers.

Mobile Network Users

• Desktop computers in offices use no wireless or mobile technology.
• Notebook computers in hotel rooms use mobile technology but are not wireless.
• Networks in older, unwired buildings use wireless technology but are not mobile.
• A portable office or a PDA for store can be both wireless and mobile.

Data Communications

• Telecommunication means communication at a distance.
• Data refers to information presented in an agreed-upon form.
• Data communications is the exchange of data between two devices via a transmission medium, such as a wire cable.
• Components of a data communications system and data flow are important
• A data communication uses the rule based "Protocols" to send messages.
• Data flow can be simplex, half-duplex, or full-duplex.
• Simplex is one direction only.
• Half-duplex can go both directions, one at a time.
• Full-duplex can go both directions at the same time.

Networks

• A network comprises devices (nodes) connected by communication links.
• Nodes can be computers, printers, or devices capable of sending/receiving data.
• Links can be cables, air, optical fiber, or any medium that transports a signal carrying information.

Network Criteria

• Performance depends on network elements and is measured by delay and throughput.
• Reliability is the failure rate of network components and is measured by availability/robustness.
• Security involves data protection from corruption or loss due to errors and malicious users.

Physical Structures

• Point-to-point connections involve a single transmitter and receiver.
• Multipoint connections involve multiple recipients from a single transmission.
• Physical topology refers to the way in which devices and connections are set up
• Types of transmission are unicast, multicast, and broadcast.

Network Classification by Transmission Technology

• Broadcast is a single communications channel shared by all machines (addresses) on the network.
• Broadcast can be logical or physical (e.g., Media Access Control (MAC) sublayer).
• Multicast involves communications to a specified group and requires a group address (e.g., multimedia multicast).
• Unicast is communication involving a single sender and a single receiver.
• Point-to-point involves connections made via links between pairs of nodes.

Network Classification by Size

• Personal area networks work the scale of 1m, in a squire meter
• Local area networks work onthe scaale of 10m - 1km in areas like rooms, building, campus
• Metropolitan Area Networks work on the scale of 10km- 100km covering Cities and Country
• Wide area networks work on the scale of 1000km - 10,000km covering continent and the planet

Categories of Networks

• Local Area Networks (LANs) cover short distances and provide local interconnectivity.
• Wide Area Networks (WANs) cover long distances and provide connectivity over large areas.
• Metropolitan Area Networks (MANs) provide connectivity over areas such as a city or campus.
• Wired LANs typically use physical broadcasting at the MAC layer, such as Ethernet or Token Ring.
• The MANs often have a backbone like FDDI (Fiber Distributed Data Interface) and ATM (Asynchronous Transfer Mode).
• Wireless LANs exist.
• Wireless Sensor Networks (WSNs) exist

Wired and Wireless LANs

• Wired LANs use an Ethernet bus or hub.
• Wireless LANs (WLANs) can operate with a base station or in ad hoc networking mode.

Network Classification by Topology

• BUS: a linear setup with flow of data
• RING: sends data unidirectionally through repeaters in a circular setup
• TREE: a headen divides and creates a tree like structure of connected nodes
• STAR: This has a central hub, switch or repeater to which each node is connected to
• STAR: Wireless Infrastructure allows nodes conenct wirelessly to a the access point.

Wide Area Networks (WANs)

• also referred to as “point-to-point” networks.
• ARPANET was a forunner to the internet
• typically hierarchical with a backbone.
• Enterprise Networks, Autonomous Systems
• VPNs (Virtual Private Networks).