Title: TCP/IP Model
AG No: 2023-ag-9914
Submitted by: Abdullah Tariq
Submitted To: Dr Akmal Rehan
Degree: Software Engineering
Section: BSSE-4th-M1
Date: 15-05-2025
University of Agriculture Faisalabad
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TCP/IP Model
Introduction:
The TCP/IP model is a fundamental framework for computer networking.
➢ It stands for Transmission Control Protocol/Internet Protocol, which are the core
protocols of the Internet.
➢ This model defines how data is transmitted over networks, ensuring reliable
communication between devices.
Working:
Whenever we want to send something over the internet using the TCP/IP Model, the TCP/IP
Model divides the data into packets at the sender’s end and the same packets have to be
recombined at the receiver’s end to form the same data, and this thing happens to maintain the
accuracy of the data.
TCP/IP model divides the data into a 4-layer procedure.
Layers:
There are four layers of TCP/IP model.
• Application Layer
• Transport Layer (TCP/UDP)
• Network/Internet Layer (IP)
• Network Access Layer
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1. Network Access Layer
Function:
This layer is responsible for the physical transmission of data over a network medium (like
Ethernet or Wi-Fi). It handles how data is framed, sent, and received on the physical network.
Scenario Example:
When you press "Send" on an email, your laptop breaks the message into small parts called
frames and sends it through WiFi to your router. The internet carries them to the receiver,
where their device puts the parts back together and shows the email.
Key Features:
• Handles framing and error detection
• Identifies the network protocol (e.g., TCP/IP)
• Examples: Ethernet (IEEE 802.3), PPP
2. Internet Layer (Network Layer)
Function:
This layer is responsible for routing data across networks using IP addresses. It determines the
best path for data to reach its destination.
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Scenario Example:
You’re sending an email from Lahore to a friend in Faisalabad. The Internet Layer breaks your
message into packets, assigns IP addresses (yours and your friend's), and routes them across
various networks using routers until they reach the correct destination.
Main Protocols:
• IP (Internet Protocol): Sends packets based on destination IP address (IPv4 or IPv6)
• ICMP (Internet Control Message Protocol): Reports network errors (e.g., unreachable
host)
• ARP (Address Resolution Protocol): Converts IP addresses to MAC addresses for delivery
on a local network
Example:
You type in a website URL. ARP helps find the MAC address of the server using its IP. If the server
is unreachable, ICMP might generate an error message like "Destination Unreachable."
3. Transport Layer
Function:
Ensures reliable (or fast, if needed) communication between two devices. It manages error
correction, data flow, and packet ordering.
Scenario Example:
When you download a file, TCP ensures that all pieces (packets) arrive correctly and in order. If
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any are missing, it requests them again. In contrast, if you're streaming a video, UDP is used—it’s
faster and doesn’t wait for missing packets.
Main Protocols:
• TCP (Transmission Control Protocol): Reliable, connection-based communication (e.g.,
downloading files)
• UDP (User Datagram Protocol): Fast, connectionless communication (e.g., live video
streaming or online games)
Example:
While accessing your online bank, TCP ensures every data packet is sent and received accurately.
If you’re watching a live football match, UDP is used to minimize delays, even if a few frames are
lost.
4. Application Layer
Function:
Provides services directly to the end user. This is where web browsers, email clients, and other
applications operate. It merges the functions of the OSI model's Application, Presentation, and
Session layers.
Scenario Example:
You log into your bank’s website via HTTPS. The Application Layer handles secure
communication, authentication, and ensures your login credentials are encrypted and
transmitted safely.
Common Protocols:
• HTTP/HTTPS (Hypertext Transfer Protocol): For accessing websites
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• SSH (Secure Shell): For secure remote access to servers
• NTP (Network Time Protocol): Synchronizes time across systems
Example:
Imagine you transfer money online. Without NTP, your computer and the bank's server might log
different times for the same transaction. This mismatch can lead to inconsistencies or errors in
banking records.
Comparison:
Aspect TCP/IP Model OSI Model
Full Form Transmission Control Protocol/Internet Protocol Open Systems Interconnection
Layer Integration Combines session and presentation layers into the Uses separate session and
application layer presentation layers
Design Approach Follows a connectionless, horizontal approach Follows a vertical layered approach
Transport Layer Does not ensure reliable delivery at the network Ensures reliable delivery of packets at
Reliability layer; reliability is handled by TCP at the transport the transport layer
layer
Protocol Protocols are tightly bound and not easily Protocols are modular and easier to
Replacement replaceable replace with technological changes
Network Layer Provides only connectionless services (via IP) Provides both connectionless and
Services connection-oriented services
Advantages:
Here are some advantages of TCP/IP.
• Interoperability: Different devices and systems can talk to each other easily.
• Scalability: It works well for both small and big networks.
• Standardization: Uses common rules so everything fits and works together.
• Flexibility: Can adjust to different types of networks and settings.
• Reliability: Makes sure data is correct and re-sent if something goes wrong..
Disadvantages:
Here are some disadvantages of TCP/IP.
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• Complex Configuration: Setting it up and managing it can be tricky.
• Security Concerns: It didn’t have strong security at first, so extra tools are needed.
• Not Great for Small Networks: It can be too heavy or complex for simple setups.
• Limited Addresses: The old system (IPv4) doesn’t have enough addresses, but IPv6 fixes
that.
• Extra Data Load: It adds extra data which can slow things down a bit.
Broad-Band and Base-Band in TCP/IP:
1. Baseband Transmission
• Definition:
Baseband transmission sends digital signals directly over the medium using a single
channel. The entire bandwidth of the cable is used for one signal at a time.
• Example:
Ethernet (LAN using coaxial cable or twisted pair) is a classic example of baseband
communication.
• Scenario:
A small office LAN setup using Ethernet over twisted pair cables (e.g., Cat5e or Cat6).
Only one device can transmit data at a time, but the system uses time-sharing and
switches to manage multiple transmissions.
• Key Points:
➢ Used for short distances
➢ Cost-effective
➢ Suitable for local networks
➢ One signal at a time
2. Broadband Transmission
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• Definition:
Broadband transmission divides the medium into multiple frequency channels, allowing
multiple signals to be sent simultaneously.
• Example:
Cable internet using coaxial cables (DOCSIS technology) where data, voice, and video
signals are transmitted simultaneously.
• Scenario:
A residential home receives internet, television, and phone services through a single
coaxial cable from an ISP. TCP/IP packets are carried over one of the frequency channels,
while others carry video and voice data.
• Key Points:
➢ Used for long distances
➢ Multiple channels on the same medium
➢ Higher complexity and cost
➢ Ideal for ISPs and multimedia transmission
Synchronous Time division multiplexing:
Time Division Multiplexing is a technique in digital communication that deals with the
transmission of several streams of data over a single communication channel.
Types:
There are two categories of TDM.
• Synchronous TDM
• Asynchronous TDM.
1. Synchronous TDM (Time Division Multiplexing)
Each device is assigned a fixed time slot to transmit data, regardless of whether it has data or
not. Time slots are grouped into frames, with one or more slots per device.
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Advantages:
• Guaranteed Bandwidth: Each stream has a fixed slot, ensuring steady transmission.
• Predictable Latency: Fixed timing leads to consistent delivery.
• Easy Synchronization: Pre-assigned slots simplify coordination.
• Good for Continuous Data: Ideal for steady, ongoing data streams.
Disadvantages:
• Bandwidth Waste: Unused slots still occupy bandwidth.
• Inflexibility: Cannot adjust to varying data needs.
• Poor for Bursty Data: Not suited for irregular or sudden data bursts.
• Costly When Idle: Channels are considered busy even when idle, increasing costs.
2. Asynchronous TDM (Time Division Multiplexing)
Asynchronous Time Division Multiplexing (or Statistical TDM) gives time slots only when data
needs to be sent. It doesn't waste time slots like the fixed method, so it’s more flexible and
efficient.
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Advantages:
• Efficient Bandwidth Use: Time slots used only when needed—no wastage.
• Dynamic Allocation: Bandwidth can be assigned based on demand.
• Ideal for Busty Data: Well-suited for irregular data transmission.
Disadvantages:
• Higher Complexity: Requires advanced control mechanisms.
• Potential Delays: May cause latency during high traffic.
• Synchronization Issues: Dynamic slots make data stream alignment difficult.
X Series & V Series
X Series:
The X Series is a group of standards defined by the ITU-T for packet-switched networks. X series
focuses on data transmission over public digital networks, including email and directory services.
Example:
Imagine you are sending a letter by post using a courier service. Each letter is put in an envelope
(like a data packet), and the courier (network) handles delivering it to the destination. X.25 is like
the postal system, ensuring your letter (data) reaches its destination safely.
V Series:
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The V series deals with modems and data transmission over telephone lines. It focuses on how
devices like computers and modems communicate over long distances.
Example:
An old dial-up internet connection where your computer used a modem to connect to the internet
using a telephone line. That modem followed V series standards, like V.92, to make sure data was
sent and received properly.
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