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osi_model

An interactive deep-dive into all 7 OSI layers — from physical signal transmission at Layer 1 through Ethernet frames, IP packets, TCP segments, all the way to HTTP at Layer 7. Covers encapsulation, protocol examples at each layer, and why the model exists.

You'll be able to click any layer to expand it, see what protocols live there, and trace a real packet as it moves up and down the stack.

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OSI Reference Model
7ApplicationHTTP · DNS · SMTP · FTP
6PresentationTLS · JPEG · ASCII · MIME
5SessionNetBIOS · PPTP · RPC
4TransportTCP · UDP · SCTP
3NetworkIP · ICMP · BGP · OSPF
2Data LinkEthernet · MAC · ARP
1PhysicalCables · Signals · Bits
devices & components at each layer
7 Application
🌐Web Browser 🖥Web Server 📧Mail Client 🔍DNS Resolver 📁FTP Client
6 Presentation
🔒TLS/SSL Engine 🗜Compression 🎞Media Codec 🔄Format Converter
5 Session
🔌OS Socket API 📡API Gateway 🔑Auth Service 🔄Session Manager
4 Transport
🛡Firewall Load Balancer 🔀NAT Gateway 🔎Deep Packet Inspect
3 Network
🌐Router 🔀L3 Switch 🔒VPN Concentrator 📡IP Gateway
2 Data Link
🔀L2 Switch 🌉Bridge 📶Wireless AP 🖧NIC (MAC addr)
1 Physical
🔌Hub 📻Repeater 🔗Ethernet Cable 💡Fibre Optic 📡Modem
data payload & encapsulation at each layer

As data travels down the stack (sender), each layer wraps the payload with its own header. Going up (receiver), each layer strips its header. The highlighted block is what each layer adds.

encapsulation — sender side (Layer 7 → Layer 1)
layer 7 Application
USER DATA (HTTP request, email body, DNS query…)
Message
raw payload
layer 6 Presentation
TLS ENCRYPT
USER DATA
Encoded Data
encrypted / formatted
layer 5 Session
SESSION ID
TLS HDR
USER DATA
Data
with session token
layer 4 Transport
TCP HDR · SRC:51234 DST:443
SESS
TLS
DATA
Segment
TCP / UDP datagram
layer 3 Network
IP HDR · 192.168.1.5 → 93.184.216.34
TCP HDR
SESS
DATA
Packet
routable unit
layer 2 Data Link
ETH HDR · aa:bb:cc → dd:ee:ff
IP HDR
TCP
DATA
FCS ✓
Frame
+ trailer checksum
layer 1 Physical
1 0 1 1 0 0 1 0 · 1 1 0 1 0 0 1 1 · 0 0 1 0 1 1 0 1 · 1 0 1 0 0 1 1 0 · 0 1 0 1 1 0 1 0 · 1 1 0 0 1 0 1 1 · …
Bits
electrical / optical
header added at this layer inherited from layer above