* What is Network? *
A network is a group of two or more computer systems linked together.
The goal of networking is to share data and resources between computers.
Each computer has its own network address, which uniquely identify it among others.
A file server is a network computer dedicated for storing programs and data that are shared among network users.
Networks are integral to computers and computing.
Point to Point Connections
| Description |
Diagram
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Area Networks
Common examples of Area Networks types are:
LAN: Local Area Network
WAN: Wide Area Network
MAN: Metropolitan Area Network
SAN: Storage Area Network
CAN: Campus Area Network
PAN: Personal Area Network
DAN: Desk Area Network
WLAN: Wireless Local Area Network
LAN and WAN were the original categories of area networks.
Local Area Network (LAN)
In LAN, the idea is to connect all the machines in a single building.
Wide Area Network (WAN)
A Wide-Area Network (WAN) connects two or more LANs, over long distances.
Topologies
In computer networking, topology refers to the layout of connected devices.
Network topologies are categorized into the following basic types:
Bus
Ring
Star
Tree
Mesh
Bus: Bus networks use a common back bone to connect all devices.
Ring: In a ring networks, every device has exactly two neighbors for communication purposes, and all messages travel through a ring in the same direction.
Star: Many home networks use the star topology, which features a central connection point called a hub.
Tree: Tree topologies integrate multiple star topologies onto a bus.
Mesh: Mesh topologies involve routes; unlike each of the previous topologies, messages sent on a mesh network can take any of several possible paths from source to destination.
LAN Topologies
| Ring |  |
| Bus |  |
| Star |  |
The OSI Model
Open System Interconnection (OSI) reference model has become an international standard and serves as a guide for networking.
There are seven layers in OSI reference model:
Physical Layer
Data Link Layer
Network Layer
Transport Layer
Session Layer
Presentation Layer
Application Layer
TCP/IP
TCP/IP is a collection of the two main communication protocols: TCP and IP.
TCP/IP is an internet communication protocol that defines the rules for the computers to communicate with each other online.
Web browsers and internet servers use TCP/IP to connect to the internet.
Email client programs such as Outlook Express etc. use TCP/IP to connect to the internet and send/receive emails.
IP Addressing
Each computer on the internet and on the network must have a unique IP address.
Each transmitted data packet must contain the IP address of the source and destination computer.
There are four octets and 32 bits in an IP address.
An IP address is made up of four numbers, each between 0 and 255. For instance “64.246.52.10”
What is the Internet?
It is a network of networks.
The Internet is a global system of interconnected governmental, academic, corporate, public, and private computer networks.
The Internet is a WAN which spans the entire planet.
The software which manages Internet communication follows a suite of protocols called TCP/IP.
The Transmission Control Protocol (TCP) dictates how messages are reassembled and handles lost information.
The Internet Protocol (IP) determines the format of the information as it is transferred.
• Protect internal networks or nodes.
Can be hardware or software based.
Examines/restricts inbound and outbound traffic.
Transmission Medium
Guided: Physical media such as copper wire.
Copper wire
Fiber-optic wire
Unguided: Air and space that carry electromagnetic signals.
Wireless (radio waves)
