Lecture 1 - Introduction to Computer Networks.pdf

LECTURE 1 INTRODUCTION TO COMPUTER NETWORKS OVERVIEW Define basic terms e.g. Network, Node, Client, Server Differentiate networks by: Distance: Local Area Network, Metropolitan Area Network, Wide Area Network Architecture: Peer-to-Peer, Client/Server Topology: Bus, Ring,...

LECTURE 1 INTRODUCTION TO COMPUTER NETWORKS OVERVIEW Define basic terms e.g. Network, Node, Client, Server Differentiate networks by: Distance: Local Area Network, Metropolitan Area Network, Wide Area Network Architecture: Peer-to-Peer, Client/Server Topology: Bus, Ring, Star, Mesh, Hybrid BASIC DEFINITIONS Computer Network: Two or more computing devices connected to communicate or share resources … which could be data, software applications, or hardware devices, the latter having a special name… BASIC DEFINITIONS Node: A computing device on a computer network Processing Devices: Phone, Tablet, Laptop, Desktop, Server Input Devices: Scanner, Camera Output Devices: Printer, Display Storage Devices: Network Attached Storage (NAS) Navigation Devices: Switch, Access Point, Router, Firewall BASIC DEFINITIONS Client: requests access to a resource Server: provides access to a resource File Server Print Server Mail Server Web Server Database Server Application Server TYPES OF NETWORKS (DISTANCE) Local Area Network (LAN) Connects two or more nodes Covers a small geographic area Room, Floor, Building, Compound Department, Branch Connection is Constant Private Fast (100 Mbps or more) TYPES OF NETWORKS (DISTANCE) Metropolitan Area Network (MAN): Covers a moderate geographic area e.g. City TYPES OF NETWORKS (DISTANCE) Wide Area Network (WAN) Connects two or more networks Floor, Building, Compound Department, Branch Covers a large geographic area Cities across a country Countries across the world The Internet Connection is Occasional Public Slow (100 Mbps or less) TYPES OF NETWORKS (DISTANCE) Personal Area Network (PAN): Connects personal devices via Bluetooth Phone, Tablet, Laptop, Desktop Speakers (including earphones and headphones) Keyboards and Mice Smart Devices Fitness Trackers Scales Blood Pressure and Blood Glucose Machines … TYPES OF NETWORKS (DISTANCE) Home Area Network (HAN): Connects devices within a home, typically via Wi-Fi using a wireless router TYPES OF NETWORKS (ARCHITECTURE) Peer-to-Peer (P2P) Computers have mixed roles (i.e. Client and Server) There is no central authority for access and resources (i.e. All are equal) Basic Operating System feature Windows 10, 8.x, 7, XP macOS Linux TYPES OF NETWORKS (ARCHITECTURE) Client/Server Computers have dedicated roles (i.e. Client or Server) There is a central authority for access and resources (i.e. There is hierarchy) Advanced Operating System feature Windows Server 2019, 2016, 2012, 2003 macOS Server Linux UNIX TYPES OF NETWORKS (TOPOLOGY) Physical Topology: How devices connect Logical Topology: How data flows BUS TOPOLOGY Single cable (called a backbone) between two terminators with nodes connected to the backbone Hardly used BUS TOPOLOGY ADVANTAGES DISADVANTAGES Inexpensive to implement Difficult to Add, Move, Change Easy to implement Difficult to troubleshoot All components are single point of failure Congestion due to broadcasts All data is seen by all nodes RING TOPOLOGY Nodes connected in sequence with each connected to the previous and the next with the last connected to the first Used for WANs RING TOPOLOGY ADVANTAGES DISADVANTAGES Inexpensive to implement All components are single point of Easy to implement failure Easy to Add, Move, Change All data is seen by all nodes Easy to troubleshoot No broadcasts STAR TOPOLOGY Central device with individual cables connecting each node Used for LAN “edge” i.e. Clients STAR TOPOLOGY ADVANTAGES DISADVANTAGES Easy to implement Expensive to implement Easy to Add, Move, Change Central device is single point of failure Easy to troubleshoot No cable or node is single point of failure Less congestion due to fewer broadcasts Data is seen by target node MESH TOPOLOGY Each node connected to each other node N.B. n (n - 1) / 2 Used for LAN “core” i.e. Servers HYBRID TOPOLOGY A mix of two or more topologies TO BE CONTINUED… THE OSI MODEL