Networking Concepts

Telegraph

by samuel Morse
electrical signals over wires
Morse code

Telephone Networks

by Alexander Graham Bell
Voice communication over wires Development of switching systems

Creation of large communication networks
Introduced the concept of “Circuit switching”

Packet switching

idea proposed by Paul Baran, Donald Davies

message is broken into small packets

Each packet travels independently, can take different routes, and is reassembled at the destination

foundation of the Internet.

ARPANET

First Internet

by US Department of Defense

Connect research universities and laboratories

TCP/IP

One of the most important developments in Internet history.

by Vint Cerf Robert Kahn

ARPANET officially switched to ______

Domain Name System

translates domain names to IP addresses.

Paul Mockapetris

NSFNET and Expansion

Purpose: Connect Universities and provide high-speed backbone network

NSF (National Science Foundation)

became the main Internet backbone for US academic research and education

was decommisioned

World Wide Web

first web browser and editor (renamed to Nexus)

Created at CERN

by Tim Berners-Lee

Nexus

First-ever web browser

Only worked on NeXT computers

Tim Berners-Lee

created at CERN

Mosaic

First browser with images + text together

Made the Web popular

by NCSA

Led by Marc Andreessen

Netscape Navigator

Secure web (SSL)
Faster browsing experience

by Netscape Communications
dominant browser in the 1990s

Internet Explorer

by Microsoft
Bundled with Windows
Browser Wars (Vs Netscape)

Modern Browsers

Key players:
•Google Chrome
•Mozilla Firefox
•Microsoft Edge
•Safari

Features: •High speed •Security •Extensions & web app

Commercial Internet

Private companies (ISPs, tech companies)

Major developments:
• email services
• Online shopping
• Websites
• Search engines

Early companies: Yahoo, Amazon, e-Bay

Modern Internet Era

supports:
• social media
• Online gaming
• Cloud computing
• Streaming
• IoT devices
• AI services

telegraph, telephone systems

Networking began with ___ and _____.

Packet switching

______ revolutionized communications

ARPANET

______ became the first internet

TCP/IP

______ enabled global networking

DNS and Web

____ and ____ made the Internet usable for everyone

cloud, IoT, and AI

The Internet continues evolving with ___, ___, and ___

Network

collection of devices that can communicate using common protocols

Network data

information that needs to be transferred a cross a network

Nodes

Networking Fundamentals –Key Components

Other term for Devices

Endpoint Devices

equipment that needs to access/share network data

Servers, Computers, Storage devices, Printers, IP phones, IP cameras, Mobile phones

Network Devices

equipment that transfers the network data between endpoint devices.

Routers, Switches, Firewalls, Wireless Access Points

Wired
Wireless

Networking Fundamentals –Key Components

2 types of Communication Medium

Twisted pair Cable
Coaxial Cable
Fiber optic Cable

Wired mediums (3)

Wifi
Cellular
Satellite/Microwave
Infrared/Bluetooth

Wireless Mediums

Protocols

a set of rules to follow when endpoint devices communicate on a network

TCP
IP
HTTP
HTTPS
FTP
DNS

Protocols (6)

Transmission Control Protocol
Internet Protocol
Hypertext Transfer Protocol
HTTP Secure
File Transfer Protocol
Domain Name System

Protocols
Acronym:

TCP
IP
HTTP
HTTPS
FTP
DNS

LAN

Types Of Network

A network that covers a small geographic area like a home, office, or building

A private network that connects devices within a limited geographic area such as an office, building campus, or data center

Connected via ethernet cable, fiber optic, or Wi-Fi

MAN

Types of network

A network that spans a city or large campus

WAN

Type of Network

A network that covers large geographic areas (countries or worldwide)

A network that connects multiple LANs across geographic areas such as cities, countries, or continents

Private _____ - traditionally connected via leased line, MPLS, private fiber, satellite, Internetbased connections, etc

Leased Line

WAN technologies:

Private connection between two sites

Multiprotocol Label Switching (MPLS)

WAN technologies:
-Managed by telecom providers
-Uses labels to route traffic efficiently

Internet Based WAN

WAN technologies:
-Uses public Internet
-Includes: VPN (Virtual Private Network)

Leased Line
MPLS
Internet Based WAN
Microwave Link
Fiber Optic Link

WAN Technologies (5)

Internet

A global public interconnected networks that connects organizations worldwide

Network topology

is the arrangement or layout of devices and connections in a network

Physical Topology
Logical Topology

Types of Topology
1. The actual physical layout

2. How data flows through the network

Star Topology

Common Types of Topology:

-Most Common
-All devices connect to a central switch/router
-Easy to manage and troubleshoot
-Used in most LANs today

Bus Topology

Common Types of Topology:

-All devices share a single cable (backbone)
-Simple but outdated
-Common in: Fieldbus networks, PLC communication systems

Ring Topology

Common Types of Topology:

-Devices form a closed loop
-Data travels in one direction
-Commonly used in factory automation systems
-Some fiber optic networks use ring structures (i.e SONET/SDH rings)

Mesh Topology

Common Types of Topology:

-Devices are fully interconnected
-Very reliable but expensive

Hybrid Topology

Common Types of Topology:

-Combination of different topologies
-Used in real-world networks

Network architecture

is the overall design of a network, including how devices are organized, how they communicate, and what technologies are used

Blueprint of the Network

Defines:
Topology, Devices, Communication protocols, Services, Security design

Client-Server Architecture
Peer-to-Peer (P2P)
Tiered Architecture
Cloud Architecture

Common Types of Architecture:
1. Clients request services, Servers provide services. ex. Web Browsing (PC —> Web Server)

2.Devices communicate directly, No Central Server. ex. File Sharing between computers

3. Two _____ = Core + Access. Three ____ Core + Distribution +Access. Used in large Organizations

4. Services hosted in data centers, Accessed via the Internet. Ex. Google Drive, AWS

Software as a Service (SaaS)
Platform as a service (PaaS)
Infrastructure as a service (IaaS)

Types of Cloud Architecture (3)
1. Control the virtual infrastructure
2. Focus on Development
3. Just use the application

Network Model

defined set of protocols used to communicate on networks.

Types of network Model

1. 7-layer model, Conceptual framework to understand networking.

2. 4-layer model, Practical model used in real-world. simplifies OSI by combining layers—3 at the top and 2 at the bottom

OSI Model

Developed by International Organization for Standardization (ISO) to ensure different systems can work together

Divides network communication into 7 layers, each with a specific function

Application layer

OSI Model:

-Serves as the window for users and application processes to access the network
- “End-user layer”
- Protocol: http, https, ftp, smtp, dns

Presentation Layer

OSI Model:

- Handles encryption, compression, formatting
- “Syntax layer”
- Ex: encryption: TLS/SSL compression : zip, gzip, png, jpeg,mp3.mpeg formatting : ASCII, HTML, Unicode, XML

Transport layer Security (TLS)

OSI Model:

is what keeps your data safe and private when you use the internet.

Does Encryption, Authentication, Data Integrity

Encryption
Authentication
Data Integrity

OSI Model:

TLS:

1. Converts readable data → unreadable (ciphertext)

2. Verifies the server using digital certificates

3. Ensures data is not modified during transmission

Session layer

OSI Model:

- Manages sessions (connections) between devices
- Common target for hackers
- Data becomes data streams

Transport Layer

OSI Model:

- Ensures data transfer and performs error detection and flow control
- Encapsulation: Session (TCP), Datagram (UDP)

- Protocol:
• TCP (Transmission Control Protocol)– reliable
• UDP (User Datagram Protocol) - unreliable

Port Numbers

OSI Model:

Transport Layer

Sends data to correct application

Network Layer

OSI Model:

- Routers operate at this layer
- Uses logical addressing (IP addresses)
- Encapsulation: Packets
- Protocol: IP, ICMP

IP

OSI Model:

Purpose: Deliver packets
Layer: 3
Carries Data: Yes
Used for: Routing across Network

ICMP

OSI Model:

Purpose: Report errors / diagnostics
Layer: 3
Carries Data: No
Used for: errors, troubleshooting

Ping

OSI Model:

Purpose: Check connectivity
Protocol: ICMP
Layer: Layer 3
Output: Success + latency
Uses TTL?: Not directly
Shows Route: No

Traceroute

OSI Model:

Purpose: Discover path (hops)
Protocol: ICPM (or UDP)
Layer: 3
Output: List of routers(hops)
Uses TTL?: Yes
Shows Route: Yes

Time to live (TTL)

OSI Model:

is a value in an IP packet that limits how long it can travel in a network

Packet
reduces TTL by 1
dropped
TTL Time Exceeded
128
64

OSI Model:

How TTL Works:
1. _____ starts with a TTL value
2. Each router ______
3. When TTL = 0
a. packet is______
b. router send ______

Default values
Windows:______
Linux: _______

ping
traceert/traceroute
routeprint/ip route
ipconfig/ip addr
arp -a/ip neigh

OSI Model:

Functions for Windows/Linux

Connectivity:
Path:
Routing Table:
IP Info:
ARP:

Data Link Layer

OSI Model:

- Layer 2 switches operates here
- Uses physical addressing (MAC addresses)
- Performs error detection within the same network
- Encapsulation: Frames
- Protocol: ARP,STP,LACP

Address Resolution Protocol (ARP)

OSI Model:

Purpose: IP → MAC mapping
Layer: Layer 2 (works with L3 info)
Used in: All IP networks
problem solved: Who has this IP?”

Spanning Tree Protocol (STP)

OSI Model:

Purpose: Loop prevention
Layer: 2
Used in: Switch networks
problem solved: Broadcast storms

Link Aggregation Control Protocol (LACP)

OSI Model:

Purpose: Link bundling
Layer: 2
Used in: Switch-to-switch links
problem solved: Bandwidth & redundancy

Physical Layer

OSI Model:

- Cables, signals, voltages and radio waves - Transmits raw bits over a physical medium - Bits

Application layer

TCP/IP Model:

- Provides services to user applications
- Performs data formatting, encryption, communication handling
- Encapsulation : Data
- Ex. http, https, ftp, smtp, pop3/imap, dns, snmp, telnet/ssh

Host to host Layer

TCP/IP Model:

-Manages end-to-end data flow, reliability, and flow control, error recovery
- Adds TCP or UDP header (port number)
- Encapsulation : Segment (TCP) , Datagram (UDP)
- Types: • TCP – reliable • UDP - unreliable

Internet layer

TCP/IP Model:

- Responsible for logical addressing and routing packets across networks
- Adds IP header ( source and destination address)
- Encapsulation : Packet
- Protocol: IP,ICMP

Network Access Layer

TCP/IP Model:

- Manages physical transmission of data, including framing, hardware addressing, and media access
- Adds Frame header (source and destination MAC address, EtherType) and trailer (error detection)
- Encapsulation : Frame
- Protocol: ARP,STP,LACP

Ethernet
Wi-FI

TCP/IP Layer 1:

1. IEEE 802.3, Wired

2. IEEE 802.11, Wireless

Twisted pair

Ethernet:

-Cat5e, Cat6 ,etc
-RJ 45 connectors
-Most common wired LAN

WG,G,WO,B,WB,O,WB,B
WO, O, WG, B, WB, G, WB, B

Order of wires
T568A
T568B

Straight Through

Ethernet, Twisted pairs

-Connects different types of devices
-Same wiring on both ends
👉 T568A → T568A or T568B → T568B

Crossover

-Connects similar types of devices
-Different wiring on each end
👉 T568A → T568B

Medium Dependent Interface (MDI)
Medium Dependent Interface Crossover (MDIX)

TCP/IP Layer 1:

_____ and ____ define how Ethernet devices use their pins to send and receive signals.

______ Used by end devices
______ Used by Network devices

Fiber Optics

Ethernet:

-Uses light signals
-Very fast, long distance
-Connectors: •Lucent Connector (LC), Subscriber Connector (SC) ,MPO/MTP

Fiber SFP

-Uses LC connectors

-Types:
• SX → short distance (multimode)
• LX → long distance (single-mode

IP Addressing

is the system used to assign a unique logical address to every device on a network so they can communicate with each other

IP Address

is a numeric label assigned to devices in a network

32 bits, dotted decimal format
128 bits, hexadecimal format

2 main versions of IP address.
Give Number of bits and format

IPv4
IPv6

Device Identification
Location Identification
Routing Identification
Internet communication

IP Addressing allows (4)

Internet assigned Numbers Authority (IANA)
Regional Internet Registries (RIR)
Local ISPs

Local identification

Ip Addresses are distributed like this

Internet Corporation for Assigned Names and Numbers (ICANN)

IANA is operated by _________

ICANN

is a non-profit organization that coordinates the global Internet’s naming and numbering systems to keep everything unique

Static IP
Dynamic IP

How IP Addresses are assigned

1. Manually Configured, Commonly used in private network

2. Automatically assigned by DHCP, Commonly used by Internet

Private IP

Types of IP by range

-Used for private network (LAN or WAN)

-Private IPs are not routable on the internet • Three main IP blocks:
• Class A (Large networks) - 10.0.0.0/8 • Class B (Medium networks) - 172.16.0.0/12 • Class C (Small/Home networks) - 192.168.0.0/16

Public IP

-Used on the Internet
-Assigned by ISP
-Range: 1.0.0.0 – 223.255.255.255
• Ex: • 8.8.8.8 – Google DNS IP

IP Addressing Exclusion

Unicast
Broadcast
Multicast
Anycast

Types of IP Addresses (By Communication Type)

1. 1 to 1 (192.168.1.1)
2. 1 to all in subnet (192.168.1.255)
3. 1 to Many (224.0.0.1)
4. 1 to Nearest if many (used in DNS)

Classful IP Addressing

- Is the original way IPv4 addresses were divided based on the first few bits of the address
- Divides IPs into fixed classes : A,B,C,D,E
- Each class has a fixed subnet mask

Problems
-Wastes addresses
-Not flexible for networks of arbitrary size
-Caused IPv4 exhaustion

Classless Inter-Domain Routing (CIDR)

-Flexible system introduced in 1993 to replace classful addressing
-Uses prefix notation (slash /) to define network bits
-Advantages: no rigid classes, efficient use of IP addresses, Allows variable-length subnetting, Reduces routing table size

Subnet mask
32-subnet mask
2^host bits

CIDR
Number of network bits = ________
No of Host Bits = ________
No of Usable hosts = _______