Networking Fundamentals​, Quick Notes – Introduction

Introduction

Networking by definition, “Sharing of resources”. Networking refers to collection of computers connected for the purpose of sharing and accessing resources. Networks are widely implemented in homes, offices, public places, etc.

Home Networks are usually simple and have fewer computers connected through devices that require almost minimal technical expertise to manage; on contrast, Enterprise Networks usually have devices that require specific product/technical expertise and may have hundreds to thousands of computers.

Resources that can be shared:

  • Files
  • Internet Connectivity
  • Printers
  • Storage Devices
  • Scanners
  • Optical Drive
  • Tape Drive
  • Projectors
  • Audio/Video

Note: Some devices cannot be shared due to specific technical limitations.

Why share?

  • Reduce costs (for example, a single printer can be shared across an entire network).
  • Security (restrict who can access shared resources).

Terminology

  • Server Devices, provide resources.
  • Client Devices, access resources.

Standards

Networking specifications are well-documented through RFCs (Request for comments), which may be referred for in-depth understanding. There are thousands of RFCs available in plain text format, you may find links to handful RFC’s in this guide.

A. Conceptual types of networks

Peer-to-Peer: All computers on a network share resources with each other, security can be controlled at each computer; suitable for home & Office networks, typically 10 – 30 computers (not a strict number).

P2P: Each computer can share their resources, local security

Client/Server: In Client/Server model, a server provides resources to its clients. A server may provide a single service or, multiple services, depending on administrator’s preference. Security may be centralized.

C/S: Resources shared from one main computer

Hybrid: Mixed (Heterogeneous), depends on administrator’s preference.

Hybrid: Mix of both P2P & Client/Server model

B. Signaling Methods

  • Defines how communication happens using electric, optical or radio signals.
  • Types
    • Baseband
      • Digital Signals
      • Use entire bandwidth
      • Uses TDM (Time-division Multiplexing), send multiple signals at different time intervals
      • Very high transfer rates
      • Example: Ethernet
    • Broadband
      • Analog Signals
      • Use part of the bandwidth
      • Uses FDM (Frequency-division Multiplexing), send multiple signals at different frequencies
      • Speed usually less when compared to Baseband, depends on technology
      • Example: DSL

TDM, time sharing – one at a time

FDM, same time at different frequencies

C. Channel Operation

  • Defines mode of communication between devices on a network.
  • Types
    • Simplex: One way communication (Similar to a Radio).
    • Half-Duplex: Two ways, one way at a time (Similar to a walkie-talkie).
    • Full-Duplex: Both ways at the same time (Similar to a telephone).

Simplex

Half-Duplex

Full-Duplex

D. Data Transmission methods

  • Defines how data is transferred over a network.
  • Types
    • Circuit Switching: Dedicated physical path (circuit) is established before transferring data; no other device can use the path until termination. Example: Dial-Up Networking.
    • Packet Switching: Data is divided as packets and sent through different paths, enabling multiple devices to communicate at the same time. Example: IP (Internet Protocol) Networks.

E. Channel Access

  • Defines how devices should use shared medium for communication.
  • Types
    • CSMA/CD (Carrier Sense Multiple Access/Collision Detect): Only one device can transmit at a time and other devices should “listen” before transmissions to avoid collisions. When two devices communicate at the same time, a collision occurs. If collision is detected, devices should retry transmissions after random interval.
    • CSMA/CA (Carrier sense multiple access with collision avoidance): Similar to CSMA/CD, designed for wireless networks. Devices sense if a channel is “idle” before transmissions.

F. Addressing Methods

  • Defines how signals should be addressed
  • Types: Unicast, Multicast & Broadcast

Unicast: One device to a specific device on a network.

Multicast: One device to selective number of devices on a network.

Broadcast: One device to all other devices in a network.

  1. Network Classification
  • LAN (Local Area Network): Refers to networks within a limited area such as within a building.
  • MAN (Metropolitan Area Network): Refers to networks within a city.
  • WAN (Wide Area Network): Refers to networks covering a large geography.
  1. Network Definitions
  • Intranet: Refers to private networks operated by an organization.
  • Extranet: Refers to private networks operated by an organization & and it’s vendors/partners.
  • Internet: Refers to interconnected computers across the globe.

Reference(s):

https://www.ietf.org/rfc/rfc1208.txt 

I. Collision & Broadcast Domains

  • When two devices send packets at the same time, a collision occurs requiring re-transmission; devices should attempt to resend packet again, after a random interval.
  • Collision happens often on shared network medium such as the Ethernet.
  • Devices
    • Hub: Single Collision & Broadcast Domain (Possibility of collision is very high since all computers belong to a single collision & broadcast domain).
    • Switch: Single Broadcast Domain and each port is a collision domain (hence very effective in reducing & managing collisions).
    • Router: Different Collision & Broadcast domains.

J. Types of Servers

  • File Servers: Used for documents, images, etc.
  • Print Servers: Allows users to access printers.
  • Web Servers: Used for serving web pages.
  • FTP Servers: Allows content such as documents, media files, etc. to be downloaded or uploaded.
  • Mail Servers: Used for sending & receiving emails.
  • Database Servers: Providescentralized access to databases. 
  • Game Servers: Allows users to play multiplayer games.
  • Media Servers: Streams Audio & Video content.
  • Domain Controllers: Used for centralized authentication.

Note: Any computer can act as a server or a client, depending on administrator’s preference. For example a desktop operating system can function as a web server, if a web server software like Apache is installed. However, using a desktop operating system as a server may have technical limitations as compared to a server operating system.

Software

Type

Platform / Operating System

Apache

Web Server

Microsoft Windows, Linux

Internet Information Services

Web & FTP Server

Microsoft Windows

FileZilla Server

FTP Server

Microsoft Windows, Linux

MySQL

Database Server

Microsoft Windows, Linux

Microsoft SQL Server

Database Server

Microsoft Windows

Microsoft Exchange

Email Server

Microsoft Windows

Zimbra

Email Server

Linux

Server Software

Server Hardware

Hardware requirements for a server are determined based on (Not limited to):

  • Server Operating System requirements.
  • Type of service(s) (web / email / storage, etc.).
  • Resource required for handling 100’s to 1000’s of client requests.

Options

  • Use a single server to provide multiple services, usually requires moderate to powerful hardware.
  • Use multiple servers to provide a single service, suitable where support for heavy load is required.
  • Spread multiple services across multiple servers.

Costs

  • Server hardware costs vary depending on underlying hardware components and software licenses.
  • Choice of CPU, HDD & HDD Technology (HDD/SSD), Storage Capacity, RAM, multiple network cards, etc. are considered depending on the purpose of a server.
  • Professional advice required to determine exact hardware requirements.
  • Servers may be purchased or leased/rented, depending on budget & preference.

Tower Model

Rack Model

Mini Model

Server operating systems

Server operating systems are designed to support higher number of CPU’s, large amounts of RAM and so on. For example, Microsoft Windows 10 (desktop operating system) can support only 2 physical processors but Microsoft Windows Server edition is designed to support 64 physical processors. Such limitations entirely depends on the edition/version of an operating system as defined by the vendor, which can be found in technical documentation.

Popular server operating systems include:

  • Microsoft Windows Server Series
  • Unix Editions
  • Several Linux Editions
  • Mac OS Server

Quiz 01

1. Networking is best defined as:

A. Sharing of Resources B. Connectivity between desktop computers
C. Connectivity between mobile computers D. The Internet

2. Resources that can be shared in a network:

A. CD-ROM Drive B. Hard Disk Drive C. Internet Connectivity D. All of the above

3. Maximum number of computers in a network:

A. 10 B. 20 C. 100 D. Unlimited

4. _____ defines network connectivity within a limited area such as a home or a small office network.

A. LAN B. MAN C. WAN D. PAN

5. _____ defines network connectivity between networks within a city.

A. LAN B. MAN C. WAN D. PAN

6. _____ defines network connectivity between networks across the globe.

A. LAN B. MAN C. WAN D. PAN

7. Acronym – LAN.

A. Limited Area Network B. Legacy Area Network
C. Local Area Network D. Local Assisted Network

8. Acronym – WAN.

A. World Area Network B. Wide Access Network
C. Wide Area Network D. Wide Assisted Network

9. Acronym – MAN.

A. Mini Area Network B. Metropolitan Area Network
C. Macro Area Network D. Metropolitan Assisted Network

10. Acronym – PAN.

A. Professional Area Network B. Personal Area Network
C. Pinned Area Network D. Pinned Assisted Network

11. _____ refers to a computer that provide resources.

A. Client B. Server C. Mobile D. Smart Net

12. _____ refers to computers that access resources.

A. Client B. Server C. Mobile D. Smart Net


13. _____ model utilizes centralized security.

A. Personal Network B. Peer-to-Peer C. Client-Server D. Mobile Area Network

14. _____ are referred to as service requestors.

A. Servers B. Clients C. Peer-to-Peer D. Client-Server

15. _____ are referred to as service providers.

A. Servers B. Clients C. Peer-to-Peer D. Client-Server

16. _____ refers to network of networks.

A. Intranet B. Internet C. LAN D. WAN

17. _____ refers to private networks used by organizations, not accessible by public.

A. Intranet B. Internet C. Peer-to-Peer D. Client-Server

18. In _____ data is sent as digital signals by using entire bandwidth of a media.

A. Broadband B. Baseband C. Digiband D. Analogband

19. In _____ data is sent as analog signals by using portion of a bandwidth.

A. Broadband B. Baseband C. Digiband D. Analogband

20. Examples of Broadband:

A. DSL B. Cable Internet C. Ethernet D. Both A & B

21. Example of Baseband:

A. Ethernet B. DSL C. Cable Internet D. Both B & C

22. Acronym – TDM.

A. Telecommunication Division Multiplier B. Time Division Multiplexing
C. Tele Division Multiplexing D. Transfer Division Multiplexing

23. Acronym – FDM.

A. Fast Division Multiplexing B. Fine Division Multiplier
C. Far Division Multiplexing D. Frequency Division Multiplexing

24. _____ refers to one-way communication.

A. Simplex B. Duplex C. Half-Duplex D. Full-Duplex

25. _____ refers to two-way communication but one direction at a time.

A. Simplex B. Duplex C. Half-Duplex D. Full-Duplex

 

26. _____ refers to simultaneous two-way communication.

A. Simplex B. Duplex C. Half-Duplex D. Full-Duplex

27. Acronym – CSMA/CD.

A. Collision Sense Multiple Access/Carrier Detect
B. Collision System Multiple Access/Carrier Detect
C. Carrier Sense Multiple Access/Collision Detect
D. Collision Sense Multiple Access/Carrier Divide

28. One-to-One communication: _____.

A. Broadcast B. Multicast C. Unicast D. Basecast

29. One-to-Many communication: _____.

A. Broadcast B. Multicast C. Unicast D. Basecast

30. One-to-All communication: _____.

A. Broadcast B. Multicast C. Unicast D. Basecast

31. Examples of Circuit switching networks:

A. PSTN B. ISDN C. GSM D. All of the above

32. Examples of Packet Switching Networks:

A. IP B. X.25 C. Frame relay D. All of the above

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