TCP/IP Model

The Internet Protocols (TCP/IP) Architecture Model

- The TCP/IP Model For General Networking Systems

Technical standards specifying the Internet protocol suite (TCP/IP) and many of its constituent protocols are maintained by the Internet Engineering Task Force (IETF). The TCP/IP suite predates the OSI model, a more comprehensive reference framework for general networking systems.  

The TCP/IP suite occupies the middle five layers of the 7-layer open system interconnection (OSI) model. The TCP/IP layering scheme combines several of the OSI layers. From an implementation standpoint, the TCP/IP stack encapsulates the network layer and transport layer (OSI layer 4). The physical layer, the data-link layer (OSI layer 1 and 2, respectively) and application layer (OSI layer 7) at the top can be considered non-TCP/IP-specific.TCP/IP can be adapted to many different physical media types.

The TCP/IP suite helps you to determine how a specific computer should be connected to the Internet and how data should be transmitted between them. It helps you to create a virtual network when multiple computer networks are connected together. The purpose of TCP/IP model is to allow communication over large distances. TCP/IP stands for Transmission Control Protocol/ Internet Protocol. It is specifically designed as a model to offer highly reliable and end-to-end byte stream over an unreliable internetwork.

- Four Abstraction Layers

The TCP/IP suite provides end-to-end data communication specifying how data should be packetized, addressed, transmitted, routed, and received. This functionality is organized into four abstraction layers, which classify all related protocols according to the scope of networking involved. From lowest to highest, the layers are:

• The Link Layer, containing communication methods for data that remains within a single network segment (link); 

• The Internet Layer, providing internetworking between independent networks; 

• The Transport Layer, handling host-to-host communication; 

• The Application Layer, providing process-to-process data exchange for applications.

Each layer of the TCP/IP model is designed for a specific purpose and exists on both the sending and receiving hosts. Each is designed so that a specific layer on one machine sends or receives exactly the same object sent or received by its peer process on another machine. These activities take place independently from what is going on in layers above or below the layer under consideration. In other words, each layer on a host acts independently of other layers on the same machine, and in concert with the same layer on other hosts.

The Internet protocol suite (TCP/IP) is the conceptual model and set of communications protocols used on the Internet and similar computer networks. It is commonly known as TCP/IP because the foundational protocols in the suite are the Transmission Control Protocol (TCP) and the Internet Protocol (IP).  

- Implementations

The Internet protocol suite does not presume any specific hardware or software environment. It only requires that hardware and a software layer exists that is capable of sending and receiving packets on a computer network. As a result, the suite has been implemented on essentially every computing platform. 

A minimal implementation of TCP/IP includes the following: Internet Protocol (IP), Address Resolution Protocol (ARP), Internet Control Message Protocol (ICMP), Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and Internet Group Management Protocol (IGMP). In addition to IP, ICMP, TCP, UDP, Internet Protocol version 6 requires Neighbor Discovery Protocol (NDP), ICMPv6, and IGMPv6 and is often accompanied by an integrated IPSec security layer.

[More to come ...]