The TCPIP Protocol Stack


The TCP/IP Protocol Stack

The TCP/IP model is an example of a protocol stack, that is, a number of protocols that work together in a well-defined hierarchy, to provide communications between devices on a network, and is the mechanism used by the Solaris operating environment. You saw in the previous chapter that a protocol is a set of rules that govern how data communication takes place. A protocol stack, such as this, is hierarchical in that the overall structure is the model itself. The structure contains a number of layers , each carrying out a separate function, and each function is subjected to certain rules about how the function is executed ”the protocol.

A protocol stack has the following properties:

  • Each layer exists to carry out a specific function.

  • Each layer is present on both the sending host and the receiving host.

  • Each layer communicates with its opposite number (peer) on another host, following well-defined procedures.

  • Each layer on a host is independent of the other layers on the same host; the relationship is with its peer layer on another host ”the application layer on host A is a peer of the application layer on host B, for example.

So, for communication to take place between two hosts , there are a number of sequential steps that must be followed; think of these steps as the layers.

There are several advantages in using a layered model:

  • The format of the data, how the data is actually transmitted, the transport mechanism used, and the actual route taken by the data are broken down into several functions (layers), thereby simplifying the issue of communicating across a network.

  • Standards exist, allowing a common approach to be taken by hardware and software suppliers.

  • Modifications can be made to one of the layers without affecting the whole model because each layer is independent of the other layers.

  • The modular structure of the layers makes resolution of problems easier because a problem will point to a specific layer or function.

Consider this simple example:

When you write a letter to someone (this is the application), you are interested only in the letter getting there in one piece and what the response is (the Transport layer). You don't have any interest in which specific route the delivery takes (the Internet layer), or in which postman delivers the letter (the Network Interface layer) ”that is the responsibility of the postal service or courier (the Application layer).



Solaris 9 Network Administration Exam Cram 2 (Exam Cram CX-310-044)
Solaris 9 Network Administrator Exam Cram 2 (Exam CX-310-044)
ISBN: 0789728702
EAN: 2147483647
Year: 2003
Pages: 174
Authors: John Philcox

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