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10-A.1: TCP/IP Fundamentals

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  • Objectives of this Module

    In this lesson, you will:

    • Describe the fundamental concepts of TCP/IP.
    • Determine the various roles that  Linux servers can play.
    • Learn how to connect to a network.
    • Learn how to configure DNS and DHCP client services.
    • Learn about configuring cloud and virtualization technologies.
    • Troubleshoot networking and connection issues.

    Linux uses networks A LOT. Therefore, we have to have some understanding of networks and how they work. Then we can build Linux specific networking skills. 

    What is a Network Protocol?

    Networks use protocols as a set of rules for formatting and processing data. Network protocols provide a common language so computers can communicate with one another. Computers within any network may use totally different software and hardware, however, protocols enable them all to communicate with each other at any time.

    When standardized protocols are used, it's like a common language that computers can use. It is just like two people from different parts of the world  trying to communicate - they may not understand each other's native languages, but they can communicate by using a shared third language. If one computer uses the Internet Protocol (IP) and a second computer also uses IP, they will be able to communicate. But if one computer uses IP and the other uses some other protocol, they will be unable to communicate.

    On the Internet, there are different protocols for different types of processes. Protocols are often discussed in terms of which OSI model layer they belong to.

    The OSI Model

    The Open Systems Interconnection model (OSI model) is a conceptual model that characterizes and standardizes the communication functions of a telecommunication or computing system without regard to its underlying internal structure and technology. Its goal is the interoperability of diverse communication systems with standard communication protocols.

    Showing the 7 layers of OSI Model: Layer 1 - Physical; Layer 2 - Datalink; Layer 3 - Network; Layer 4 - Transport; Layer 5 - Session; Layer 6 - Presentation; Layter 7 - Application
    Figure \(\PageIndex{1}\): The OSI Model ("The OSI Model " by Bill MacKenty is licensed under CC BY-NC-SA 4.0)

    The model partitions the flow of data in a communication system into seven abstraction layers, from the physical implementation of transmitting bits across a communications medium to the highest-level representation of data of a distributed application. Each intermediate layer serves a class of functionality to the layer above it and is served by the layer below it. Classes of functionality are realized in software by standardized communication protocols.

    The TCP/IP Model

    The Internet protocol suite is the conceptual model and set of communications protocols used in 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). During its development, versions of it were known as the Department of Defense (DoD) model because the development of the networking method was funded by the United States Department of Defense through DARPA. Its implementation is a protocol stack.

    The Internet protocol 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 inter-networking between independent networks; the transport layer, handling host-to-host communication; and the application layer, providing process-to-process data exchange for applications.

    TCP/IP Stack compared to OSI Model. Also some of the  applications/utilities that run at each of the TCP/IP layers. The TCP/IP Network Interfacelayer is the same OSI Layer 1 and 2. At this layer the routers and switches and ethernet run. TCP/IP layer 2 - Network is the same as the OSI  Network layer. IP and Arp run in this layer. The TCP/IP and OSI Transport and OSI is next. It runs TCP and UDP. The TCP/IP Application layer encompasses the Session, Presentation and Application layer in the OSI model. The protocols that run here are http, ftp, telnet,ping and dhcp
    Figure \(\PageIndex{1}\): TCP/IP Model diagram. ("TCP/IP Model diagram" by Ardika6879Wikimedia Commons is licensed under CC BY-SA 4.0)

    Adapted from:
    "OSI model" by Multiple ContributorsWikipedia is licensed under CC BY-SA 3.0
    "Internet protocol suite" by Multiple ContributorsWikipedia is licensed under CC BY-SA 3.0

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