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Lesson 3 TCP/IP protocol suite
ObjectiveDescribe the use of the TCP/IP Protocol Stack

TCP/IP Protocol Stack and Suite

The TCP/IP protocol stack, also known as the TCP/IP suite, is a set of communication protocols used for transferring data over networks. It is named after the two most important protocols in the stack: the Transmission Control Protocol (TCP) and the Internet Protocol (IP). The TCP/IP suite is comprised of four layers, each responsible for a different aspect of network communication:
  1. The Application layer: This layer includes protocols that are used by applications for exchanging data with other applications over the network. Examples of application layer protocols include HTTP, SMTP, FTP, and Telnet.
  2. The Transport layer: This layer is responsible for ensuring that data is transferred reliably between two endpoints on the network. The most commonly used transport layer protocol is TCP, which provides reliable, ordered delivery of data.
  3. The Internet layer: This layer is responsible for routing data between different networks. The Internet Protocol (IP) is the primary protocol used at this layer.
  4. The Network Access layer: This layer includes protocols that govern the physical transmission of data over the network, such as Ethernet, Wi-Fi, and Bluetooth.

Together, these four layers make up the TCP/IP protocol stack, which is the foundation of the modern internet and most other computer networks. The TCP/IP suite is widely used because it is a flexible and open standard that can be implemented on a wide range of devices and operating systems. It is also highly scalable, allowing it to support networks of various sizes, from small local area networks to large global networks such as the internet.

What is the TCP/IP Protocol Stack?

(TCP/IP) Transmission Control Protocol/Internet Protocol is a group of communication protocols developed to network dissimilar systems. Its structure follows the ISO Reference Model discussed earlier. While the ISO Model generically identifies the seven protocol layers used to achieve robust communications, the TCP/IP is a particular suite of protocols adopted as the global standard for Internet-based communications. The illustration below shows that the TCP/IP suite (also called the TCP/IP stack) appears in the Network Layer of the OSI Model's protocol stack. Because of this, all network applications can be written to easily interface with the TCP/IP protocols without regard to a particular network software manufacturer or medium.
Protocol stack
TCP/IP: 1. HTTP, 2. FTP, 3. Other High Level Protocols, 4. Custom Protocols
TCP and IP form the TCP/IP protocol stack (or "suite of protocols") that enables dissimilar computer systems to communicate.

What is TCP?

TCP is a "connection-oriented" protocol that guarantees delivery of data packets from a specific source to a specific destination. It provides reliable, end-to-end delivery. Transmission Control Protocol (TCP) is a core communication protocol of the internet protocol suite, which is responsible for reliable and ordered delivery of data between applications running on different hosts connected to a network. TCP operates at the Transport layer of the TCP/IP protocol stack and provides a reliable and error-checked stream of data between two endpoints. It is a connection-oriented protocol that establishes a virtual connection between two devices before transmitting data. TCP breaks data into smaller packets called segments, assigns sequence numbers to each segment, and reassembles them at the receiving end in the correct order. It also implements a flow control mechanism to prevent the receiver from being overwhelmed with data. TCP uses a three-way handshake mechanism to establish a connection between two endpoints, where the sender and receiver exchange a series of SYN (synchronization) and ACK (acknowledgment) packets to synchronize and establish a connection. Once the connection is established, data can be transmitted in both directions. TCP is widely used in the transmission of data over the internet, particularly for applications such as web browsing, email, and file transfer. Its reliability and error-checking mechanisms make it suitable for applications where data integrity is crucial.

What is (IP) Internet Protocol?

IP routes packets around the Internet, and performs route discovery, fragmentation, and re-assembly of those packets. This means IP finds the fastest route to its destination, is able to determine the 'optimal' route moment by moment, and will re-order the packets into their proper sequence at the destination computer. The Internet Protocol (IP) is a core communication protocol of the internet protocol suite, which is responsible for routing data packets between devices connected to a network. IP operates at the Internet layer of the TCP/IP protocol stack and provides a connectionless, best-effort delivery service. It is responsible for addressing packets and routing them across a network to their destination. IP breaks data into packets, assigns each packet an IP address that identifies the destination device, and routes the packets through the network using the best available path. If a packet encounters a problem along the way, such as congestion or a broken link, IP will try to route the packet around the problem or send it back to the sender if it cannot be delivered. IP addresses are numerical identifiers assigned to devices connected to a network. IPv4, the most widely used version of IP, uses a 32-bit address scheme, which allows for approximately 4.3 billion unique addresses. IPv6, a newer version of IP, uses a 128-bit address scheme, which allows for a virtually unlimited number of unique addresses. IP is a fundamental protocol of the internet and is used in virtually all network communication, from web browsing and email to video streaming and online gaming. Its best-effort delivery service makes it suitable for applications where real-time data transfer is not critical, while its address and routing mechanisms enable global communication between devices on the internet.

Client Server Architecture

UDP (User Datagram Protocol):

UDP (User Datagram Protocol) is a connectionless protocol, considered the "poor cousin" of TCP. Whenever TCP sends a packet it numbers them sequentially, then queries the destination computer to see if they all arrived. UDP sends unnumbered packets (called datagrams) and never queries. UDP is faster than TCP because fewer bits are required per packet and no queries are sent. UDP is typically reserved for low-priority messages, such as scheduled server outage times to all users on a LAN. User Datagram Protocol (UDP) is a communication protocol of the internet protocol suite that provides a connectionless, unreliable data transfer service. UDP operates at the Transport layer of the TCP/IP protocol stack and is used for applications where reliability is not critical, such as real-time audio and video streaming, online gaming, and other time-sensitive applications. Unlike TCP, UDP does not establish a virtual connection between two devices before transmitting data. Instead, it sends data packets called datagrams directly to the destination device, without any confirmation that the data has been received. UDP does not implement error-checking or retransmission mechanisms, which makes it a less reliable protocol than TCP. However, it is faster and more efficient than TCP because it does not have the overhead of establishing and maintaining a virtual connection. UDP is often used in applications where speed and low latency are more important than reliability. For example, in online gaming, a small delay in transmitting data can have a significant impact on gameplay, so UDP is used to minimize latency. Similarly, in video streaming applications, a delay in receiving data can cause buffering, so UDP is used to provide a smoother playback experience.
In the next lesson, you will learn about TCP/IP addresses and how they are classified.

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