Computer Networks – Summary
Notes
Introduction
A computer network is a collection of interconnected
devices that share resources and data.
Networks are designed to enable communication, resource
sharing, and data exchange.
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OSI Model (Open Systems Interconnection)
The OSI model has 7 layers, each with specific functions.
Layer Function Examples
7. Application User interface, network services HTTP, FTP,
SMTP, DNS
, 6. Presentation Data translation, encryption,
compression SSL, JPEG, ASCII
5. Session Session management between hosts APIs,
NetBIOS
4. Transport Reliable data transfer, error recovery TCP,
UDP
3. Network Logical addressing, routing IP, ICMP
2. Data Link Error detection, framing Ethernet, PPP
1. Physical Transmission media, signaling Cables, Hubs
Mnemonic: “Please Do Not Throw Sausage Pizza Away”
(Physical → Application)
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🖧 TCP/IP Model
The TCP/IP model has 4 layers that map to the OSI model:
TCP/IP Layer Corresponding OSI Layers Protocols
Notes
Introduction
A computer network is a collection of interconnected
devices that share resources and data.
Networks are designed to enable communication, resource
sharing, and data exchange.
---
OSI Model (Open Systems Interconnection)
The OSI model has 7 layers, each with specific functions.
Layer Function Examples
7. Application User interface, network services HTTP, FTP,
SMTP, DNS
, 6. Presentation Data translation, encryption,
compression SSL, JPEG, ASCII
5. Session Session management between hosts APIs,
NetBIOS
4. Transport Reliable data transfer, error recovery TCP,
UDP
3. Network Logical addressing, routing IP, ICMP
2. Data Link Error detection, framing Ethernet, PPP
1. Physical Transmission media, signaling Cables, Hubs
Mnemonic: “Please Do Not Throw Sausage Pizza Away”
(Physical → Application)
---
🖧 TCP/IP Model
The TCP/IP model has 4 layers that map to the OSI model:
TCP/IP Layer Corresponding OSI Layers Protocols
