Network protocols are basic for establishing communication between devices in a network. They specify the regulations, traditions and conventions of sending data and help in the effective exchange of information between devices. As you stated, these can be distinguished according to their role in the OSI model or the TCP/IP.
1. OSI Model (7 Layers)
The OSI model divides network communication into seven layers, from physical transmission to application interaction. The protocols are grouped based on the layer they operate within.
Layer 1: Physical Layer
Function: Defines the physical means of transmitting data over a network, including cables, switches, and hardware.
Protocols:
Ethernet: A family of protocols for wired networks (though it technically operates in both Layer 1 and Layer 2).
DSL (Digital Subscriber Line): Provides broadband access over telephone lines.
Wi-Fi: Wireless networking protocol.
Layer 2: Data Link Layer
Function: Manages how data is formatted for transmission over the physical medium. It ensures error-free transmission.
Protocols:
Ethernet: Defines how data is packaged into frames for transmission.
PPP (Point-to-Point Protocol): Used for direct connections between two network nodes.
HDLC (High-Level Data Link Control): A bit-oriented protocol used in point-to-point and point-to-multipoint communication.
MAC (Media Access Control): Handles access to the shared physical medium (Ethernet uses MAC addresses).
Layer 3: Network Layer
Function: Determines how data packets are routed across the network, including addressing and forwarding.
Protocols:
IP (Internet Protocol): The fundamental protocol for addressing and routing packets on the internet (IPv4, IPv6).
ICMP (Internet Control Message Protocol): Used for diagnostic and error messages (e.g., ping).
ARP (Address Resolution Protocol): Maps IP addresses to MAC addresses in a local network.
Routing protocols (e.g., OSPF, BGP): Used for determining the best route for data.
Layer 4: Transport Layer
Function: Provides reliable data transfer between devices and ensures the integrity of the data.
Protocols:
TCP (Transmission Control Protocol): Ensures reliable, ordered data transmission with error checking.
UDP (User Datagram Protocol): Provides faster, connectionless data transfer without guarantees (e.g., streaming or VoIP).
SCTP (Stream Control Transmission Protocol): A reliable message-oriented protocol that allows multiple streams in one connection.
Layer 5: Session Layer
Function: Manages sessions or connections between applications. It handles establishing, maintaining, and terminating communication sessions.
Protocols:
RPC (Remote Procedure Call): Allows a program to execute code on a remote server.
NetBIOS (Network Basic Input/Output System): Provides session and communication services in local networks.
Layer 6: Presentation Layer
Function: Translates data between the application layer and the network, ensuring that data is in a readable format (e.g., encryption, compression).
Protocols:
SSL/TLS (Secure Sockets Layer / Transport Layer Security): Used to encrypt data to ensure secure communication (e.g., HTTPS).
MIME (Multipurpose Internet Mail Extensions): Standard for email formatting and attachments.
JPEG, GIF, PNG: Image formats used for visual data translation.
Layer 7: Application Layer
Function: Provides network services directly to end-user applications. This is the layer users interact with directly.
Protocols:
HTTP/HTTPS (Hypertext Transfer Protocol/Secure): Used for web browsing and secure communication.
FTP (File Transfer Protocol): Used for transferring files between clients and servers.
SMTP (Simple Mail Transfer Protocol): Used for sending emails.
POP3/IMAP (Post Office Protocol/Internet Message Access Protocol): Used for receiving and managing emails.
DNS (Domain Name System): Resolves human-readable domain names to IP addresses.
2. TCP/IP Model (4 Layers)
The TCP/IP model is a more simplified, practical model used for real-world networking. It consolidates some of the OSI layers into broader categories.
Layer 1: Link Layer (Data Link + Physical)
Function: Deals with the physical transmission of data and the methods for local delivery between network devices.
Protocols:
Ethernet
Wi-Fi
PPP
Layer 2: Internet Layer
Function: Handles packet forwarding, addressing, and routing between devices across different networks.
Protocols:
IP (IPv4/IPv6)
ICMP
ARP
Routing protocols (e.g., BGP, OSPF)
Layer 3: Transport Layer
Function: Provides communication services for applications and ensures reliable data transfer.
Protocols:
TCP
UDP
SCTP
Layer 4: Application Layer
Function: Provides network services directly to the applications used by end-users.
Protocols:
HTTP/HTTPS
FTP
SMTP
DNS
Telnet
Common Network Protocols Overview
- TCP/IP: Provides end-to-end communication services for applications over the internet, combining the transport and internet layers.
- HTTP/HTTPS: Foundation for web browsing and secure connections.
- FTP/SFTP: File transfer protocols, where FTP is less secure and SFTP adds encryption for security.
- SMTP/IMAP/POP3: Email protocols for sending and receiving messages.
- DNS: Resolves domain names to IP addresses, allowing access to websites by name.
Ref : Internet
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