logging in or signing up Network Models ankush85 Download Post to : URL : Related Presentations : Let's Connect Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Copy embed code: Embed: Flash iPad Dynamic Copy Does not support media & animations Automatically changes to Flash or non-Flash embed WordPress Embed Customize Embed URL: Copy Thumbnail: Copy The presentation is successfully added In Your Favorites. Views: 2254 Category: Education License: All Rights Reserved Like it (2) Dislike it (0) Added: May 23, 2009 This Presentation is Public Favorites: 1 Presentation Description No description available. Comments Posting comment... Premium member Presentation Transcript Slide 1: 2.1 Network Models Slide 2: 2.2 2-1 LAYERED TASKS We use the concept of layers in our daily life. As an example, let us consider two friends who communicate through postal mail. The process of sending a letter to a friend would be complex if there were no services available from the post office. Sender, Receiver, and CarrierHierarchy Topics discussed in this section: Slide 3: 2.3 Figure 2.1 Tasks involved in sending a letter Slide 4: 2.4 2-2 THE OSI MODEL Established in 1947, the International Standards Organization (ISO) is a multinational body dedicated to worldwide agreement on international standards. An ISO standard that covers all aspects of network communications is the Open Systems Interconnection (OSI) model. It was first introduced in the late 1970s. Layered ArchitecturePeer-to-Peer Processes Encapsulation Topics discussed in this section: Slide 5: 2.5 ISO is the organization.OSI is the model. Slide 6: 2.6 Figure 2.2 Seven layers of the OSI model Slide 7: 2.7 Figure 2.3 The interaction between layers in the OSI model Slide 8: 2.8 Figure 2.4 An exchange using the OSI model Slide 9: 2.9 2-3 LAYERS IN THE OSI MODEL In this section we briefly describe the functions of each layer in the OSI model. Physical LayerData Link Layer Network Layer Transport Layer Session Layer Presentation Layer Application Layer Topics discussed in this section: Slide 10: 2.10 Figure 2.5 Physical layer Slide 11: 2.11 The physical layer is responsible for movements of individual bits from one hop (node) to the next. Slide 12: 2.12 Figure 2.6 Data link layer Slide 13: 2.13 The data link layer is responsible for moving frames from one hop (node) to the next. Slide 14: 2.14 Figure 2.7 Hop-to-hop delivery Slide 15: 2.15 Figure 2.8 Network layer Slide 16: 2.16 The network layer is responsible for the delivery of individual packets from the source host to the destination host. Slide 17: 2.17 Figure 2.9 Source-to-destination delivery Slide 18: 2.18 Figure 2.10 Transport layer Slide 19: 2.19 The transport layer is responsible for the delivery of a message from one process to another. Slide 20: 2.20 Figure 2.11 Reliable process-to-process delivery of a message Slide 21: 2.21 Figure 2.12 Session layer Slide 22: 2.22 The session layer is responsible for dialog control and synchronization. Slide 23: 2.23 Figure 2.13 Presentation layer Slide 24: 2.24 The presentation layer is responsible for translation, compression, and encryption. Slide 25: 2.25 Figure 2.14 Application layer Slide 26: 2.26 The application layer is responsible for providing services to the user. Slide 27: 2.27 Figure 2.15 Summary of layers Slide 28: 2.28 2-4 TCP/IP PROTOCOL SUITE The layers in the TCP/IP protocol suite do not exactly match those in the OSI model. The original TCP/IP protocol suite was defined as having four layers: host-to-network, internet, transport, and application. However, when TCP/IP is compared to OSI, we can say that the TCP/IP protocol suite is made of five layers: physical, data link, network, transport, and application. Physical and Data Link LayersNetwork LayerTransport Layer Application Layer Topics discussed in this section: Slide 29: 2.29 Figure 2.16 TCP/IP and OSI model Slide 30: 2.30 2-5 ADDRESSING Four levels of addresses are used in an internet employing the TCP/IP protocols: physical, logical, port, and specific. Physical AddressesLogical AddressesPort AddressesSpecific Addresses Topics discussed in this section: Slide 31: 2.31 Figure 2.17 Addresses in TCP/IP Slide 32: 2.32 Figure 2.18 Relationship of layers and addresses in TCP/IP Slide 33: 2.33 In Figure 2.19 a node with physical address 10 sends a frame to a node with physical address 87. The two nodes are connected by a link (bus topology LAN). As the figure shows, the computer with physical address 10 is the sender, and the computer with physical address 87 is the receiver. Example 2.1 Slide 34: 2.34 Figure 2.19 Physical addresses Slide 35: 2.35 Most local-area networks use a 48-bit (6-byte) physical address written as 12 hexadecimal digits; every byte (2 hexadecimal digits) is separated by a colon, as shown below: Example 2.2 07:01:02:01:2C:4B A 6-byte (12 hexadecimal digits) physical address. Slide 36: 2.36 Figure 2.20 shows a part of an internet with two routers connecting three LANs. Each device (computer or router) has a pair of addresses (logical and physical) for each connection. In this case, each computer is connected to only one link and therefore has only one pair of addresses. Each router, however, is connected to three networks (only two are shown in the figure). So each router has three pairs of addresses, one for each connection. Example 2.3 Slide 37: 2.37 Figure 2.20 IP addresses Slide 38: 2.38 Figure 2.21 shows two computers communicating via the Internet. The sending computer is running three processes at this time with port addresses a, b, and c. The receiving computer is running two processes at this time with port addresses j and k. Process a in the sending computer needs to communicate with process j in the receiving computer. Note that although physical addresses change from hop to hop, logical and port addresses remain the same from the source to destination. Example 2.4 Slide 39: 2.39 Figure 2.21 Port addresses Slide 40: 2.40 The physical addresses will change from hop to hop, but the logical addresses usually remain the same. Slide 41: 2.41 Example 2.5 A port address is a 16-bit address represented by one decimal number as shown. 753 A 16-bit port address represented as one single number. You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.