Network Communication Overview Purpose: This chapter reviews general networking theory and introduces students to some of Cisco’s product line. Timing: This chapter takes approximately 1.5 hours to present. Note: This section has a product selection tool laboratory exercise at the end. Contents: Objectives—This section explains what the student will be able to do at the end of this chapter. Defining Network Components—This section displays where devices are placed in the network. Mapping Business Needs to a Hierarchical Model—This section describes the heirarchical model used in network design. OSI Model Overview—This section reviews the OSI model. Communicating Between Layers—This section describes encapsulation and de-encapsulation. Written Exercise 1—This section has a written exercise to test the students’ knowledge of the OSI model. Physical Layer Functions—This section describes the physical layer of the OSI Model. Data Link Layer Functions—This section describes the data link layer of the OSI Model. Network Layer Functions—This section describes the network layer of the OSI Model. Transport Layer Functions—This section describes the transport layer of the OSI Model.

Network Communication Topics Packet delivery process OSI model overview Purpose: this figure states the chapter objectives. Emphasize: Read or state each objective so each student has a clear understanding of the chapter objectives.

Packet Delivery Process Data package assembled Packet addressed Packet placed on medium Purpose: this figure states the chapter objectives. Emphasize: Read or state each objective so each student has a clear understanding of the chapter objectives.

OSI Model Overview Application Application (Upper) Layers Presentation Session Layer 1 of 2: Purpose: This figure orients the students to the OSI model. Emphasize: This model should be a review for students who attend this course. Gage the depth of your discussion around the knowledge of the students. Transition: The following layer discusses the lower layers of the OSI reference model.

OSI Model Overview Application (Upper) Layers Presentation Session Transport Layer Layer 2 of 2: Purpose: This figure orients the students to the next set of concepts. Emphasize: The Data Link layer of the OSI reference model is implemented by Switches and Bridges. These devices encapsulate date in “frames”. The Network layer of the OSI reference model is implemented by Routers. These devices encapsulate data in ‘packets’. The Transport layer of the OSI reference model is implemented by various protocols; one of which is TCP. TCP uses ports and encapsulates the data in ‘segments’. Network Layer Data Flow Layers Data Link Physical

Role of Application Layers EXAMPLES Telnet HTTP Application Network services Slide 1 of 4: Purpose: This figure orients the students to the application layer. Emphasize: This layer discusses network applications rather than computer applications. So, applications such as spreadsheets, word processors, or presentation graphics are not the applications being described here. Network applications may be applications that support, electronic mail, file transfer, remote access, network management, and so on. Transition: The following discusses the presentation layer.

Role of Application Layers EXAMPLES Telnet HTTP Application Network services ASCII EBCDIC JPEG Presentation How data is presented Slide 2 of 4: Purpose: This figure orients the students to the presentation layer. Emphasize: This layer discusses code formatting, data presentation standards, and conversion. Transition: The following discusses the session layer.

Role of Application Layers EXAMPLES Telnet HTTP Application Network services ASCII EBCDIC JPEG Presentation How data is presented Keeping different applications’ data separate Session Slide 3 of 4: Purpose: This figure orients the students to the session layer. Emphasize: This layer coordinates applications as they interact on different hosts. Examples of session-layer protocols include: NFS, SQL, RPC, and so on. Transition: The following displays the lower layers. Sockets

Role of Application Layers EXAMPLES Telnet HTTP ASCII EBCDIC JPEG Sockets Application Network services Presentation How data is presented Keeping different applications’ data separate Session Slide 4 of 4: Purpose: This figure orients the students to the entire OSI model stack. Emphasize: The lower layers sit below the upper three layers. The remainder of this course is focused on the lower layers. Transition: The following discusses the physical layer of the OSI reference model. Transport Layer Network Layer Data Link Physical

Role of Data Flow Layers EXAMPLES Slide 1 of 5 Purpose: This figure orients the students to the physical layer of the OSI Model. Emphasize: The physical layer specifies the electrical, mechanical procedural, and functional requirements for activating, maintaining, and deactivating the physical link between systems. Certain physical standards are associated with certain data link standards. For example, 802.3 is used with data link standard 802.2 for Ethernet. It is not used in WAN connections. This is covered more in-depth later in the course. Transition: The following discusses Layer 2, the Data Link layer, of the OSI reference model. Move bits between devices Specifies voltage, wire speed and cable pin-outs Ethernet cable Physical

Role of Data Flow Layers EXAMPLES Slide 2 of 5: Purpose: This figure orients the students to the data link layer. Emphasize: The data link layer provides data transport across a physical link. 802.3 is and physical and data link Ethernet protocol. It is used with the 802.2 standard. Transition: The following discusses Layer 3, the network layer, of the OSI reference model. Device addressing Media Access Control Ethernet driver Data Link Move bits between devices Specifies voltage, wire speed and cable pin-outs Ethernet cable Physical

Role of Data Flow Layers EXAMPLES Logical addressing Routing Network IP Slide 3 of 5: Purpose: This figure orients the students to the network layer. Emphasize: Network layer is where IP occurs. Transition: The following discusses Layer 4, the transport layer, of the OSI reference model. Device addressing Media Access Control Data Link Ethernet driver Move bits between devices Specifies voltage, wire speed and cable pin-outs Physical Ethernet cable

Role of Data Flow Layers EXAMPLES Reliable or unreliable delivery Segmentation TCP UDP Transport Logical addressing Routing Network IP Slide 4 of 5: Purpose: This figure orients the students to the transport layer. Emphasize: The Transport layer of the OSI reference model is implemented by various protocols; one of which is TCP. TCP uses ports and encapsulates the data in ‘segments’. TCP is connection oriented so it offers reliable service. The other major transport layer protocol discussed in this course is UDP. It offers speed but no reliability because it is connectionless. Transition: The following presents the entire OSI stack again. Device addressing Media Access Control Data Link Ethernet driver Move bits between devices Specifies voltage, wire speed and pin-out cables Physical Ethernet cable

Role of Data Flow Layers Application Presentation EXAMPLES Session Reliable or unreliable delivery Segmentation TCP UDP Transport Logical addressing Routing Network IP Slide 4 of 5: Purpose: This figure orients the students to the transport layer. Emphasize: The Transport layer of the OSI reference model is implemented by various protocols; one of which is TCP. TCP uses ports and encapsulates the data in ‘segments’. TCP is connection oriented so it offers reliable service. The other major transport layer protocol discussed in this course is UDP. It offers speed but no reliability because it is connectionless. Transition: The following presents the entire OSI stack again. Device addressing Media Access Control Data Link Ethernet driver Move bits between devices Specifies voltage, wire speed and pin-out cables Physical Ethernet cable

Encapsulating Data PDU Segment Transport Network Packet Data Link Application Presentation PDU Session Upper Layer Data Segment Transport TCP Header Upper Layer Data Network Packet IP Header Data Purpose: This figure illustrates encapsulation. Emphasize: The protocol data units (PDUs) are the terms used in the industry and in this course to describe data at the different layers. Encapuslation is a key concept that illustrates how data is formatted prior to being sent across a link. This example is an illustration is Ethernet (or token ring) at the data link and physical layer and TCP/IP at the network and transport layers. Transition: The following discusses de-encalsulation. Data Link Frame MAC Header Data FCS 0101110101001000010 Physical Bits

De-encapsulating Data IP + TCP + Upper Layer Data Application Presentation Session Upper Layer Data Transport Upper Layer Data TCP Header Network TCP+ Upper Layer Data Purpose: This figure illustrates de-encapsulation. Emphasize: At the destination, the headers at each layer are stripped off as the data moves back up the stack. IP Header IP + TCP + Upper Layer Data Data Link LLC/MAC Header Physical 0101110101001000010

Functional Responsibilities Written Exercise: OSI Model OSI Model PDU Functional Responsibilities Examples Application Presentation Session Transport Purpose: This exercise is intended to re-enforce students understanding of the OSI model. Note: Students should fill in the empty spaces to complete the table. Answers are in the “Answers” appendix. Network Data Link Physical