Network Notes PDF

OSI and TCP/IP Models Physical layer (1) - Deals with physical connections (e.g., cables, switches) and signal transmission ( electrical, optical, or radio waves) - Example Ethernet cables , fiber optics Data link layer (2) - Provides error- free data transfer between two devices on t...

OSI and TCP/IP Models Physical layer (1) - Deals with physical connections (e.g., cables, switches) and signal transmission ( electrical, optical, or radio waves) - Example Ethernet cables , fiber optics Data link layer (2) - Provides error- free data transfer between two devices on the same network - Handles MAC (media Access Control) addresses and frames - Example Switches, NIC (Network Interface Card) Network layer (3) - Handles routing, logical addressing (IP), and forwarding of packets between networks - Example Routers and IP Transport layer (4) - Ensures reliable data delivery (e.g., TCP for guaranteed delivery, UDP for faster but unreliable transfer - Example TCP, UDP Session layer (5) - Manages sessions, including initiation, maintenance, and termination of communication between devices - Example Authentication protocols Presentation Layer (6) - Translates data into a format the application can understand (e.g., encryption, compression) - Example SSL (Secure Sockets Layer ) encryption and TLS (Transport Layer Security) Application Layer (7) - Interfaces with user application for data transfer (e.g., HTTP, FTP, DNS) - Example Web browser , email clients **TCP/IP model** 1. Network Interface later - Combines OSI layer 1 and 2 (Physical and Data Link) - Handles MAC addressing, Physical Connections and framing of data 2. Internet Layer - Equivalent to OSI layer 3 (Network) - Responsible for IP addressing and packet routing 3. Transport layer - Matches OSI layer 4 (Transport) - Provides end to end Communication using TCP/UDP Protocols 4. Application Layer - Combines OSI layer 5,6,7 (Session, Presentation , Application - Handles user-facing applications and protocols like HTTP, FTP, and DNS OSI Model TCP/IP Model ------------------------------------- ------------------- Physical, Data Link Network Interface Network Internet Transport Transport Session, Presentation , Application Application Common Ports Numbers and their Application Port Number Protocol/service Description ------------- ------------------ ------------------------------------------------------------------------------- 80 HTTP Standard web browsing (Unencryted) 443 HTTPS Secure Web browsing using SSL/TLC Encrytion 25 SMTP Sending emails (Simple Mail Transfer Protocol) 20/21 FTP File Transfer Protocol **20 for** data transfer **, 21 f**or control commands 53 DNS Resolves domain name into IP addresses Devices and their Corresponding OSI/TCP layer **Device** **OSI Layer(s)** **TCP/IP Layer(s)** ------------------ ---------------------------------------------------------------- ----------------------------- **Switch** Layer 2 (Data Link, MAC-based), Layer 3 (for Layer 3 switches) Network Interface, Internet **Router** Layer 3 (Network, IP-based) Internet **Network Card** Layers 1 (Physical) and 2 (Data Link) Network Interface