Understanding the TCP/IP Model

• The TCP/IP model is a fundamental framework for computer networking and stands for Transmission Control Protocol/Internet Protocol.

Key Aspects:

• Defines how data is transmitted over networks, ensuring reliable communication between devices.
• The model consists of four layers: Link, Internet, Transport, and Application.

Historical Context:

• Designed and developed by the Department of Defense (DoD) in the 1960s, based on standard protocols.
• Developed alongside the creation of ARPANET, which later became the foundation of the modern internet.

Model Comparison:

• A concise version of the OSI model, containing four layers compared to the OSI model's seven.

Data Transfer:

• Transfers data from one device to another reliably and accurately by dividing data into packets and combining them at the receiving end.

Flexibility:

• Used in the real-world internet, adapting to various physical media and network technologies.

How the Model Works:

• Divides data into packets at the sender's end, which are then recombined at the receiver's end to maintain accuracy.
• Organized into a 4-layer procedure, with data passing through the layers in order and in reverse order to ensure proper organization at the receiver's end.

Layers:

• Network access layer identifies the packet's network protocol type and provides error prevention and framing.

Internet or Network Layer:

• Parallels the functions of OSI’s Network layer, responsible for the logical transmission of data over the entire network.
• Main protocols: IP (Internet Protocol) is responsible for delivering packets by looking at IP addresses in the packet headers
• ARP (Address Resolution Protocol) finds the hardware address of a host from a known IP address.

Internet Layer Example:

• When sending an email, the email is broken down into smaller packets and sent to the Internet Layer for routing.
• The Internet Layer assigns an IP address to each packet and uses routing tables to determine the best route for the packet to reach its destination.

Transport Layer:

• Exchanges data receipt acknowledgments and retransmits missing packets to ensure packets arrive in order and without error
• End-to-end communication is achieved through protocols like TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).
• TCP transmits data character-by-character, with a starting point, the whole transmission in byte order, and an ending point, while UDP provides a datagram delivery service without verifying connections.

Application Layer:

• Combines the functions of the OSI model's Application, Presentation, and Session layers, responsible for end-to-end communication and error-free data delivery
• Main protocols: HTTP (Hypertext Transfer Protocol) for communications between web browsers and servers, HTTPS (HTTP-Secure) for secure transactions, SSH (Secure Shell) for encrypted connections, and NTP (Network Time Protocol) for synchronizing computer clocks.

Host-to-Host Layer:

• Also known as the transport layer, ensures reliable data transfer using error correction and flow control
• Breaks up large blocks of data into smaller segments for efficient transmission, multiplexes data from multiple sources onto a single network connection, and provides connection-oriented service for end-to-end communication.

Physical Layer:

• The TCP/IP model is designed to be independent of the underlying physical media.
• Typically handled by hardware components and standards specific to the physical medium being used.

Other Common Internet Protocols:

• The main rule of these Internet Protocols is how the data is validated and sent over the Internet.

Advantages of TCP/IP Model:

• Promotes compatibility and cooperation among diverse systems, scalable for both small and large networks, based on open standards and protocols, and adaptable to different networking needs.

Disadvantages of TCP/IP Model:

• Setting up and managing a TCP/IP network can be complex

Security concerns:

• TCP/IP was not originally designed with security in mind.
• The older IPv4 system has a limited address space.
• TCP includes a significant amount of overhead to ensure reliable transmission, which can reduce efficiency.

Conclusion:

• Essential for modern internet communication due to its flexibility, scalability, and widespread adoption.

Relation to IP:

• Works with both IPv4 and IPv6 seamlessly.

Number of Layers:

• The OSI Model has seven layers, while the TCP/IP Model has four layers, making it simpler and more practical.

Computer Network Definition:

• A system where two or more devices are linked together to share data, resources, and information.

Basics of Computer Networking:

• A collection of interconnected devices that share resources and information.

Networking Elements:

• At least two computers.

Basic Characteristics of Computer Networks:

• Multiple devices connect and share resources like files, printers, and internet access
• Key characteristics include the data transfer method (wired or wireless) and the network's layout (such as star or mesh).

Physical Components of Computer Network:

Include hardware devices and media (server, client, peer, transmission media, and connecting devices) that enable connectivity and data exchange Types of Computer Networks

LAN (Local Area Network):

• Links devices in a single office, building, or campus over a short distance

MAN (Metropolitan Area Network):

• Spans over a metropolitan area, providing high-speed data communication services between multiple LANs and WANs

WAN (Wide Area Network):

• Connects multiple smaller Local Area Networks (LANs).

Internetworking:

• An association between different nodes or segments through intermediary devices such as routers or gateways

Internet, Intranet, and Extranet:

• Utilized for various applications, each meeting specific roles for knowledge acquisition, exchange, and organization.

Protocol Hierarchy:

• A fixed set of rules and conventions governing communication between computers
• Allows for modular design, interoperability, and ease of implementation in computer networks.

Network Devices:

• Physical devices like hubs, repeaters, bridges, switches, routers, gateways, and brouters that manage and direct data flow in a network
• Ensure communication between hardware components on a computer network.

Router:

• A networking device that forwards data packets between computer networks

Gateways:

• Connect two different configuration networks and convert protocols to allow smooth communication between networks.

Network Switch:

• Segments networks into different subnetworks (subnets or LAN segments)

Network Topology:

• The arrangement of the various elements (links, nodes, etc.) of a computer network

OSI (Open Systems Interconnection) Model:

• A set of rules explaining how different computer systems communicate over a network, developed by the International Organization for Standardization (ISO)
• OSI Model consists of 7 layers and each layer has specific functions and responsibilities:

Physical Layer:

• The bottom-most layer, providing a physical and electrical representation of the system via network components such as power plugs, connectors, receivers, and cable types

Data Link Layer:

• The second layer from the bottom, ensuring node-to-node delivery of data within the same local network and error-free transmission of information

Session Layer:

• The 5th layer, controlling connections between computers, responsible for setting up, coordinating, and terminating conversations, exchanges, and dialogues.

Presentation Layer:

• The 6th layer, serving as a data translator for the network and manipulating data as per the requirements of the application layer

Application Layer:

• The top layer, providing functionality to send and receive data from users and acting as the interface between the user and the application.

Protocols and Standards:

• Rules and guidelines that allow devices and systems to communicate and work together smoothly.

Data Link Layer Protocols:

• Ensure that bits and bytes received are identical to those being transferred.

TCP/IP Ports:

• Logical addresses for different types of internet communication, with each service like websites or email having its port for data transmission and reception.

TCP (Transmission Control Protocol):

• A connection-oriented protocol for communications that helps in the exchange of messages between different devices over a network, operating at the transport layer of the OSI model.

TCP 3-Way Handshake:

SYN (Synchronize), SYN-ACK (Synchronize-Acknowledge), and ACK (Acknowledge) steps

TCP Services and Segment Structure:

• Provides a reliable transport service using the network layer service by the IP protocol

TCP Connection Establishment:

• Connection establishment involves a three-way handshake to reserve resources at both ends

Timers:

• TCP uses several timers to ensure that excessive delays are not encountered during communications

Fast Recovery:

• A packet loss recovery technique to tackle congestion states

Data Communication:

• Sends or receive data.

MAC (Media Access Control):

• A series of rules through which devices can transfer data among them in a network, identified by a unique MAC address.

Channel Allocation Problem:

• Multiple devices share a limited number of communication channels, aiming to efficiently allocate channels while avoiding interference or congestion.

Multiple Access Protocols:

• Control how data is transmitted when multiple devices try to communicate over the same network, ensuring efficient and collision-free data packet transmission.

Carrier Sense Multiple Access (CSMA):

• Each device first sense the channel before sending the data.
• If the channel is busy, the device waits until it is free

Collision Detection in CSMA/CD (Carrier Sense Multiple Access/Collision Detection):

• When there used to be shared Bus Topology and each node (Computers) was connected by Coaxial Cables.

Controlled Access Protocols:

• Stop and Wait ARQ sends a data frame and then waits for an acknowledgment before sending the next frame, reliable delivery of data frames.

Selective repeat protocol:

• When the go-back-n protocol works well if errors are less, but if the line is poor it wastes a lot of bandwidth on retransmitted frames.

Piggybacking:

• The technique of delaying outgoing acknowledgment temporarily and attaching it to the next data packet, enhancing efficiency.

IPv4 (Internet Protocol version 4):

• Widely used system for identifying devices on a network, using a set of four numbers separated by periods to give each device a unique address.

IPv6:

• The most common version of the Internet Protocol currently, increasingly used and deployed especially in mobile phone markets

Classful IP Addressing:

• Organizing and managing IP addresses, with a 32-bit unique address having an address space of 232

Classless Addressing in IP Addressing:

• Identifies a network on the internet via a 32-bit binary mask

Classful vs. Classless Addressing:

• Classful addressing divides IP addresses into fixed classes.
• Classless addressing, also known as CIDR (Classless Inter-Domain Routing), offers more flexibility.

CIDR (Classless Inter-Domain Routing):

• A method of IP address allocation and routing that allows for more efficient use of IP addresses than traditional classful addressing.

Supernetting and Subnetting:

• Subnetting divides a large network into smaller networks (subnets), enhancing security and management
• Supernetting is the process of combining multiple networks into a larger network.