Explain the functions and layers of the TCP/IP protocol suite. Compare it with OSI.

 

TCP/IP PROTOCOL SUITE – TOPICS & SUBTOPICS (NO THEORY)

1. Definition

  • Formal definition of TCP/IP protocol suite

2. Architecture Overview

  • 4-layer architecture

    • Application Layer

    • Transport Layer

    • Internet Layer

    • Network Interface Layer

3. Application Layer

  • Application layer services

  • Application layer protocols

    • HTTP

    • FTP

    • SMTP

    • POP3

    • IMAP

    • DNS

    • SNMP

  • User-level application support

  • Data representation functions

  • Network management functions

  • Naming services

4. Transport Layer

  • Transport-layer responsibilities

  • Process-to-process communication

  • Port addressing

  • Flow control

  • Error control

  • Congestion control

  • Encapsulation & decapsulation

  • Multiplexing & demultiplexing

  • Protocols

    • TCP

    • UDP

    • SCTP

5. Internet Layer

  • Logical addressing

  • Routing

  • Best-effort delivery

  • Fragmentation & reassembly

  • Internet Layer Protocols

    • IP

    • ICMP

    • IGMP

    • ARP

    • RARP

6. Network Interface Layer

  • Data-link services

  • MAC addressing

  • Framing

  • Physical transmission

  • LAN/WAN technologies

    • Ethernet

    • Wi-Fi

    • PPP

    • Token Ring

COMPARISON WITH OSI MODEL – TOPICS & SUBTOPICS (NO THEORY)

1. Layer Count

  • OSI: 7 layers

  • TCP/IP: 4 layers

2. Layer Mapping

  • OSI vs TCP/IP layer relationships

  • Application–Presentation–Session → Application

  • Transport → Transport

  • Network → Internet

  • Data link + Physical → Network Interface

3. Design Approach

  • OSI: conceptual model

  • TCP/IP: protocol-based model

4. Protocol Support

  • OSI protocol independence

  • TCP/IP protocol dependence

5. Reliability

  • Reliability distribution in OSI

  • TCP-only reliability in TCP/IP

6. Addressing

  • OSI addressing types

  • TCP/IP addressing types

7. Connection Services

  • Connection-oriented services

  • Connectionless services

8. Usage

  • OSI: reference

  • TCP/IP: implementation





FIGURE NUMBERS (NO THEORY)

TCP/IP Protocol Suite – Figures

  • Fig. 1.5.1 – TCP/IP Reference Model

  • Fig. 1.5.2 – Relation of Protocols in TCP/IP Model

  • Fig. 1.5.3 – TCP/IP Layers and Associated Addresses

OSI Model – Figures

  • Fig. 1.4.1 – Layers, Protocols, and Interfaces

  • Fig. 1.4.2 – Communication Between Layers

  • Fig. 1.4.3 – Encapsulation/Decapsulation Between Two Sites

  • Fig. 1.4.4 – Connectionless and Connection-Oriented Service

  • OSI Layer Diagram (CS3591 Notes: standard OSI 7-layer diagram – no explicit figure number)



1. Introduction to TCP/IP Protocol Suite

The TCP/IP protocol suite is a standardized, layered communication architecture used in the Internet. It defines how data is formatted, addressed, transmitted, routed, and received across interconnected networks.
It was developed by DARPA and is the foundation of all modern internetworking.

2. Features of TCP/IP Protocol Suite

  • Provides interoperability across heterogeneous networks

  • Supports end-to-end communication

  • Provides logical addressing (IPv4/IPv6)

  • Supports connectionless and connection-oriented services

  • Includes protocols for routing, error control, application services, security

3. Architecture of TCP/IP Protocol Suite

TCP/IP follows a 4-layer model (mapped from OSI's 7-layer model):

  1. Application Layer

  2. Transport Layer

  3. Internet Layer

  4. Network Interface Layer

4. Detailed Functions of Each TCP/IP Layer

4.1 Application Layer

(Combines Application + Presentation + Session layers of OSI)

Functions:

  • Provides services for user-level applications

  • Handles file transfer, email, remote login, web access

  • Performs high-level data formatting and representation

  • Supports network management and name resolution

Important Protocols:

  • HTTP – Web access

  • FTP – File transfer

  • SMTP, POP3, IMAP – Email services

  • DNS – Domain name to IP mapping

  • SNMP – Network management

4.2 Transport Layer

(Provides process-to-process communication)

Functions:

  • End-to-end reliable delivery (TCP)

  • Connection management

  • Flow control, error control & congestion control

  • Port addressing & multiplexing

  • Supports both connectionless and connection-oriented transfers

Protocols:

  • TCP – Reliable, connection-oriented, stream-based service

  • UDP – Unreliable, connectionless, fast datagram-based service

4.3 Internet Layer

(Corresponds to OSI Network layer)

Functions:

  • Logical addressing (IPv4 / IPv6)

  • Routing of packets across networks

  • Fragmentation and reassembly

  • Best-effort delivery service

  • Provides path determination through routers

Protocols:

  • IP – Main protocol for packet forwarding

  • ICMP – Error reporting and diagnostics

  • ARP / RARP – MAC-to-IP and IP-to-MAC mapping

  • IGMP – Multicast management

4.4 Network Interface Layer

(Combines OSI Data Link + Physical layers)

Functions:

  • Physical transmission of frames

  • Framing, MAC addressing, error detection

  • Media access control

  • Defines how frames are placed on network media

Technologies/Protocols:

  • Ethernet

  • Wi-Fi

  • Token Ring

  • PPP

  • Frame Relay

5. Overall Functions of TCP/IP Protocol Suite

  • Encapsulation and decapsulation of data

  • Addressing at multiple levels (MAC, IP, Port, Application)

  • Reliable and unreliable communication modes

  • Routing and congestion control

  • Support for both LAN and WAN communication

  • Error reporting and diagnostics

6. Advantages of TCP/IP Protocol Suite

  • Highly scalable and flexible

  • Enables global internetworking

  • Provides end-to-end delivery

  • Supports multiple routing protocols

  • Handles error reporting, fragmentation, addressing