OSI Model

KILLjoy — Mon, 17 Mar 2025 05:18:15 +0000

WHAT IS OSI MODEL - OSI model is just a 7 layers framework that standardizes a network communication. i meant to establish a common format or set of rules that ensures consistency and compatibility. so OSI model set a standard for network communication so ensuring the data travels sender to receiver efficiently or we can say he OSI model has 7 layers that help computers talk to each other in a structured way.

What if we do not follow network standards-
The communication between devices and network would be chaotic like-
Different companies will create their own networking protocols so it makes impossible to communicate other companies manufactured devices. Ex-A Dell laptop might not be able to connect to an HP printer or a Cisco router.

Without standardization, different regions or companies might use separate protocols, making global internet communication difficult or impossible.Ex-Websites hosted in one country might not be accessible in another due to differing network structures.

1️⃣ Physical Layer (Wires & Signals) – "How to send data?"
Transmits raw bits (0s & 1s) through cables, fiber, or radio signals.(because computer networks data travels two main transmission mediums- (1).Data travels through a physical medium (cables). (2).Data travels through the air using electromagnetic waves.).

Devices: Hubs, Repeaters, Cables (Ethernet, Fiber).
Protocols: Ethernet (Physical part), Bluetooth, Wi-Fi (Radio signals).

Functions:

Bit Transmission – Converts data into electrical, optical, or radio signals.
Modulation & Encoding – Converts digital signals for transmission.
Transmission Medium – Uses copper, fiber optics, or wireless.
Synchronization – Ensures sender and receiver are in sync.

2️⃣ Data Link Layer (Direct Connection) – "Who am I connected to?"

Ensures error-free data transfer between two directly connected devices using MAC addresses.

** Devices:** Switches, Bridges, Network Interface Cards (NICs).
Protocols: MAC, ARP, PPP, Ethernet (Frame handling).

Functions:

MAC Addressing – Identifies devices in a local network.
Error Detection & Correction – Uses CRC (Cyclic Redundancy Check).
Frame Synchronization – Divides data into frames. Flow Control – Prevents overwhelming slower devices.

3️⃣ Network Layer (Routing & IP Address) – "Where is it going?"
Finds the best path for data using IP addresses and handles packet forwarding.

Devices: Routers, Layer 3 Switches.
Protocols: IP (IPv4/IPv6), ICMP (Ping), OSPF, RIP.

Functions:
Logical Addressing (IP) – Assigns unique IPs to devices.
Routing – Finds the best path for data.
Fragmentation & Reassembly – Splits large packets for transmission.
Error Handling – Uses ICMP for troubleshooting (Ping).

4️⃣ Transport Layer (Delivery Control) – "How to send it?"
Ensures data is fully delivered using TCP (reliable) or UDP (fast).

Devices: Firewalls (manage traffic flow).
Protocols: TCP (WhatsApp messages), UDP (Live streaming, gaming).

Functions:
Segmentation & Reassembly – Splits data into segments and reassembles it.
Flow Control – Ensures the receiver isn’t overwhelmed.
Error Control – Ensures complete and correct data delivery.
Multiplexing – Handles multiple connections at once.

5️⃣ Session Layer (Connections & Communication) – "How long do we talk?"
Manages sessions (start, maintain, and end) between applications.

Devices: Application servers, Proxy servers.
Protocols: NetBIOS, RPC, PPTP (VPNs).

Functions:
Session Establishment – Starts and maintains sessions.
Synchronization – Saves session data in case of disconnection.
Session Termination – Ends communication properly.
Token Management – Prevents multiple applications from interfering.

6️⃣ Presentation Layer (Data Formatting & Encryption) – "How to present it?"
Converts, encrypts, and compresses data for the application layer.

Devices: Encryption devices (SSL/TLS terminators).
Protocols: SSL/TLS (HTTPS security), JPEG, MP3, GIF.

Functions:
Data Formatting – Converts data for different systems (ASCII, Unicode).
Compression – Reduces file sizes for faster transmission.
Encryption & Decryption – Protects data from hackers (SSL/TLS).
Character Encoding – Ensures different languages are correctly displayed.

7️⃣ Application Layer (User Interaction) – "What does the user see?"
Provides the interface for users to interact with network services.

Devices: Web servers, Email servers, DNS servers.
Protocols: HTTP/HTTPS (Web), FTP (File transfer), SMTP (Email), DNS (Domain names).

Functions:
User Interaction – Provides web browsing, email, file sharing, etc.
Data Representation – **Ensures proper formatting for applications.
**Authentication – Verifies users before accessing services.
Error Handling – Displays proper messages for failed requests.

JS Eventloop and Nodejs event loop different or not?

KILLjoy — Sun, 12 May 2024 05:59:42 +0000

They are not the same. It's a similar concept. Both have their own eventloop. Node js event loop is somewhat advanced version customized for server environment.

Now you must be wondering how these two event loops work together?I was stuck for a long time and how these both work together. Then I asked someone.His youtube channel-https://www.youtube.com/@codingscenes/videos. He provides me some pics helped me lot!

Let's suppose you have clicked a button that will bring users result on UI
How does this go from front-end to back-end

FRONTED

BACKEND

FRONTED

Hope you have understood a little🙃.
Special Thanks ♥️-https://www.codingscenes.com/

Position-relative and absolute

KILLjoy — Thu, 22 Dec 2022 04:50:14 +0000

1.Relative
When your are using position relative it relative to itself means relative will try to position itself according to it's current position.

So above image shows that suppose you have given a green box container position:relative top:20px this green box will moves it's current position.

2.Absolute
When you are using position absolute it will try to look first it's ancestor(parent) if we have defined the position relative over there(parent),so it position according to its ancestor.otherwise it will position according your browser or other dimensions.

Above images when u do green box position:absolute left:20px and in black container you have defined a position:relative so the green box will move its parent position or we can say its ancestor if parent doesn't defined position relative . then it will look browser dimensions.

ThankYou!😃
Keep learning new things.

Git Graph Extension In Vs Code

KILLjoy — Sun, 30 Jan 2022 06:18:24 +0000

Recently, I watched a github tutorial. and i found out a fascinating git tool extension in vs code called "Git Graph".

If you working a bigger projects.Lots of people commit there code and merge in other branches so sometimes it pretty much confusing to see their commit and merging.

This extension help pretty good visualization of the my branch in relation to other branches.something this-

You can also see who made commit full details about it.
thanks!

DEV Community: KILLjoy

OSI Model

JS Eventloop and Nodejs event loop different or not?

Position-relative and absolute

Git Graph Extension In Vs Code