31. TCP IP

TCP/IP is the most widely used network protocol suite. It is not one single protocol, but a group of protocols used for communication across networks.

It was developed before the OSI model and focuses on the core functions needed for real-world networking.

TCP/IP has four layers:

• Application Layer – provides protocols used by applications and service
• Transport Layer – moves data between devices
• Internet Layer – handles packet creation and logical addressing
• Network Interface Layer – handles how data moves across the physical network

Main protocols
At the Transport Layer, the two main protocols are:

• TCP – connection-oriented and reliable
• UDP – connectionless and faster, but with less reliability

At the Internet Layer:

• IP handles addressing and routing
• ICMP is used for network status, error reporting, and tools like ping and traceroute
• IGMP is used for multicast group management

At the Application Layer:

• FTP
• TFTP
• Telnet
• SMTP
• SNMP
• NFS

At the Network Interface Layer:

• Ethernet
• Fast Ethernet
• Token Ring
• FDDI

TCP/IP vs OSI
TCP/IP has 4 layers, while OSI has 7.
The TCP/IP Application Layer covers the OSI Application, Presentation, and Session layers.
The TCP/IP Network Interface Layer covers the OSI Data Link and Physical layers.

Main Idea
TCP/IP is the standard protocol suite for networking, using layered protocols to handle application communication, transport, addressing, and network access.