Ch. 2 Communication Models Review

We use models to simplify explanation when the real object is too ______ to visualize in human terms

The OSI model is complex and understanding its functions is crucial to understanding data ______

The OSI model describes these functions and generally specifies the order in which they take place in ______

The OSI model goes from the concrete to the ______

This analogy bears a close similarity to the OSI model for end-user-to-end-user ______

It is important that you grasp what these models represent, as almost all discussions of protocols and standards are based on these ______

The International Organization for Standardization Open Systems Interconnection model is a model of the functionality required to communicate from the source end user to the destination end ______

One critical question should be addressed here: how did the sending user know that the letter was ______

To understand data communications, it is important that you grasp what these models represent, as almost all discussions of protocols and standards are based on these ______

Conversely, when you filled out the PO, you did not consider how many places the envelope that contained it would be picked up at and delivered to on its way to the end ______

THIS STANDARD DEFINES THE ______ BUS, A BUS TOPOLOGY THAT USES A TOKEN-PASSING ACCESS

THE RATIONALE BEHIND THE IEEE 802 MODEL AND ITS SPECIFICATIONS IS THIS: IF YOU MEET THE EXTERNAL INTERFACE REQUIREMENTS OF THE LLC LAYER, THEN YOUR COMMUNICATIONS WILL WORK REGARDLESS OF THE UNDERLYING ______ TECHNOLOGY BEING USED

We will look at four types of application models: one-tier, two-tier, three-tier, and ______

The Business Services are an extremely important part of the system; they supply the organization, as well as the boundaries, procedures, and ______

An example of a one-tier model is established in the 1980s, when the functional model for a stand-alone PC running a check balancing program in which check data is stored in a simple database, such as ______

In control systems, the publisher-subscriber approach is a better method for exchanging ______

Using the publisher-subscriber method, a client application communicates a request to a server and is put on a list to receive a response when the value ______

This request can be for a one-time receipt of ______

The subscriber application is provided by the ______

The majority of databases of any size are managed by relational database management systems, such as ______, Oracle, or SQL Server

The Open Systems Interconnection reference model is an attempt to standardize the functionality of end-user to end-user computer communications. OSI Model Some communications systems built today are OSI compliant. In the OSI model, the line of demarcation between data communications and data processing exists at the border between the ______ and Session layers

The Physical layer provides the mechanical and electrical means of connecting to the medium, be it copper, fiber optic, or wireless. Physical Layer Some examples of the Physical layer include Electronic Industries Alliance /Telecommunications Industry Association 232, EIA/TIA 485, or the LAN network interface card. The Physical layer provides line termination and/or impedance matching as well as synchronization of data. For every connection or task requiring communications, there will be a set of SAPs: the source service access point and the destination access service point Service Access Points or the User Datagram Protocol SAPs are nothing more than addresses in memory assigned by whatever program is controlling the communications The ______ layer performs end-user-to-end-user routing

The Internet Protocol and Internet Packet Exchange , along with the OSI Internet protocol, are all concerned with routing and the path that packets take from end user to end user. The Transport layer is responsible for reliable end-user-to-end-user communications Transport Layer The most common Transport protocols are TCP, which is connection-oriented, and UDP, which is connectionless TCP is not OSI compliant, yet it has Layer 4 functionality and is the de facto standard for data communications today The Session layer is concerned with the jobs at hand and with scheduling jobs from the Applications layer through the Presentation layer ______

It allocates system resources as required and communicates commands to the Transport layer The Session layer establishes virtual connections and closes them when the communication tasks are complete The Presentation layer ensures that the communications data has the correct syntax for the Applications layer Presentati on Layer The Presentation layer ensures that communications are performed in a common language; the encryption and decryption of the data is usually performed at the Presentation layer This layer also ensures that all the data typing and formatting will interface with the Application and Session layers Application layer functions are extremely high level compared to the bit functions at the Physical layer ______

The Application layer is much like an operating system using a graphical user interface The Application layer takes requests and gives output to the user in the user’s required form The Tortuous Path The Tortuous Path ∙The Network layer ensures that both the receive and send IP addresses are in the proper locations in the protocol header at the sending end, and that this is the correct station at the receiving end Originating at about the same time as the OSI ISO model, the Internet model defines data communications in only five layers, as figure 2-5 illustrates The Internet Model The Internet model is the most widely used protocol model for all data communications The Data Link and Physical layers generally follow the IEEE 802 model , but the Network layer always uses the IP format, which is currently defined as either version 4 or version The TCP/IP suite, as currently delivered, provides a number of standard applications , in addition to the Layer 3 and 4 functions The IEEE 802 Model ∙ IEEE 802 was established as a local area network specification ∙ This standard divides the OSI Data Link layer into two distinct sublayers: Media Access Control and Logical Link Control ∙ IEEE 802 also defines how different standard networks are to be physically connected: what form of media access they should use and how the user will interface data to the Data Link layer Logical Link Control ∙ The number 802 is the designation for the main IEEE committee for LAN standardization and specification ∙ An example is 802.3, the standard for a Carrier Sense Multiple Access with Collision Detection network and a formalization of Ethernet IEEE 802 CURRENTLY SPECIFIES SIX DIFFERENT LAN TECHNOLOGIES, MANY OF WHICH WILL BE DISCUSSED AT SOME LENGTH IN LATER CHAPTERS: IEEE 802.3: THIS STANDARD DEFINES THE CSMA/CD NETWORK AND DESCRIBES SIX LAN TYPES: 10BASE5, 10BASE2, 10BASE-T, 100BASE-T, 1000BASE-T, AND 10000BASE-T IEEE 802. ______

The Internet model is the most widely used protocol model for all data communications The Data Link and Physical layers generally follow the IEEE 802 model , but the Network layer always uses the IP format, which is currently defined as either version 4 or version The TCP/IP suite, as currently delivered, provides a number of standard applications , in addition to the Layer 3 and 4 functions The IEEE 802 Model ∙ IEEE 802 was established as a local area network specification ∙ This standard divides the OSI Data Link layer into two distinct sublayers: Media Access Control and Logical Link Control ∙ IEEE 802 also defines how different standard networks are to be physically connected: what form of media access they should use and how the user will interface data to the Data Link layer Logical Link Control ∙ The number 802 is the designation for the main IEEE committee for LAN standardization and specification ∙ An example is 802.3, the standard for a Carrier Sense Multiple Access with Collision Detection network and a formalization of Ethernet IEEE 802 CURRENTLY SPECIFIES SIX DIFFERENT LAN TECHNOLOGIES, MANY OF WHICH WILL BE DISCUSSED AT SOME LENGTH IN LATER CHAPTERS: IEEE 802.3: THIS STANDARD DEFINES THE CSMA/CD NETWORK AND DESCRIBES SIX LAN TYPES: 10BASE5, 10BASE2, 10BASE-T, 100BASE-T, 1000BASE-T, AND 10000BASE-T IEEE 802. ______