The document discusses networking fundamentals and the OSI model. It describes the OSI model as having 7 layers that define protocols for network communication. Each layer has a specific function, with layer 1 being the physical level and layer 7 the application level. Common protocols are assigned to their respective layers, such as IP addresses and routing at layer 3. The model provides a standardized way to understand network communication across different systems.

1. Networking
Fundamentals
UAS TSR Training Program
Atria Paula Nidar, ECE
NOC Engineer

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Describing a Network
 OSI Model

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What is Network?
A network is two or more computer systems interconnected
together by some form of transmission medium that enables them to
share information.

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PC A PC B

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OSI Model (Open Systems Interconnection)
Developed by International
Organization for Standardization (ISO)
reference model or standard of
communication system
 Aid understanding of how a network
system works in terms of both the
hardware and software components
by separating the function each layers.

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Advantage of using OSI Model
Intervendor
Operability
Ease of
troubleshooting
Ease of
understanding

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OSI Model
Layer 7: Application
Layer 6: Presentation
Layer 5: Session
Layer 4: Transport
Layer 3: Network
Layer 2: Data Link
Layer 1: Physical
Note that there are different protocols that run in each layers.
Segments
Packets
Frames
Bits

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Layer 7: Application
Functions: provide an interface for software programs on network hosts that have
established a communications channel through the lower-level protocols to exchange
data.
Protocols at Application Layer:
• http
• https
• ftp
• smtp
• tftp

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Layer 6: Presentation
Function: Takes care that the data is sent in such a way that the
receiver will understand the information (data) and will be able to use
the data
Protocols at Application Layer:
• Jpeg
• Png
• Mp3
• mp4

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Layer 5: Session
Function:
Allows users on different machines to establish active
communications sessions between them.
It is responsible for establishing, maintaining, synchronizing,
terminating sessions between end-user applications
Examples: When accessing mobile banking

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Layer 4: Transport
Function: Responsible for the reliable transfer of data, by ensuring that data
arrives at its destination, error-free, and in order.
Segmentation
• Data received is divided
into small data unis
Flow Control
• Controls the amount of
data of being transmitted
Error Control
• Retransmit loss data by
using checksum

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Layer 4: Transport
Flow control

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Layer 4: Transport
Protocols
• Transmission Control
Protocol
• User Datagram Protocol
Services
• Connection Oriented
Transmission
• Connectionless
Transmission
Examples: Youtube videos,
sending email
Examples: Livestreaming,
VOIP Calls

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Layer 3: Network
Function: Responsible for routing packets from the source host to the destination host
Responsible for moving data around a network of
networks, known as an internetwork or the Internet.
Logical / IP address is a unique address that
identifies a device on the internet or a local network
•Class A: 10.0. 0.0 — 10.255. 255.255.
•Class B: 172.16. 0.0 — 172.31. 255.255.
•Class C: 192.168. 0.0 — 192.168. 255.255
Routing - Determines the best path to a particular
destination network and then routes data accordingly

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Layer 3: Network
Source IP Address Destination IP Address

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Layer 2: Data Link
Functions: Responsible for controlling the transfer of the frames across
the local media
2 Sublayer
• Media Access Control – provides control for accessing the transmission medium
mac address is physical address which is burned into the NIC or communication card ni device from its
manufacturer
• Logical Link Control – connection services

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Layer 2: Data Link

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Layer 1: Physical
Functions:
Responsible for sending bits from one computer to another
Defines how the cable is attached to the network adapter
Devices involves:
Copper cable
Fiber optic cable cable
Hub
Antenna

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How the OSI model works
ENCAPSULATION DECAPSULATION