Lec03_Networks.pdf

Basic Networking Lecture 3: Network Reference Models OSI and TCP/IP Models Lecture Objectives 02 04 Benefits of Reference models. TCP/IP and OSI models. 01 Reference models: an overview 03 OSI model layers illustration. 05 Addressing in networks. OSI 0 0 0 0 0 0 0 5 5R 5000000 R 0 0 0 0 0 0 0 5 ❑ Co...

Basic Networking Lecture 3: Network Reference Models OSI and TCP/IP Models Lecture Objectives 02 04 Benefits of Reference models. TCP/IP and OSI models. 01 Reference models: an overview 03 OSI model layers illustration. 05 Addressing in networks. OSI 0 0 0 0 0 0 0 5 5R 5000000 R 0 0 0 0 0 0 0 5 ❑ Computers have different architecture so communication cannot be done in the right way. ❑ There is a need for model (Framework or Rules) to enable communication. Ne tw o rk Re fe re nc e Mo de ls ❑A framework (guideline) for network implementation and troubleshooting. ❑Divides complex functions into simpler components (layers). ❑Importance of reference model: ▪ Vendor interoperability “standardization”: multiple vendors can communicate together. ▪ Better understanding of data transfer: Through layering. ❑Reference model types : OSI (Open System Interconnection ). TCP/IP (Internet Model). Advantage s o f R.M Divide s the ne tw o rk c o mmunic atio n pro c e ss into smalle r and simple r c o mpo ne nts. 1 4 2 Allo w s multiple -ve ndo r de ve lo pme nt thro ugh standardizatio n o f ne tw o rk c o mpo ne nts. 3 Enc o urage s industry standardizatio n by de fining w hat func tio ns o c c ur at e ac h lay e r o f the mo de l. Allo w s vario us ty pe s o f ne tw o rk hardw are and so ftw are to c o mmunic ate. 1 OSI Re fe re nc e Mo de l OSI Re fe re nc e Mo de l The OSI (Open Systems Interconnection) model is the primary architectural model for networks. It describes how data and network information are communicated from an application on one computer, to an application on another computer. The model was defined by the International Organization for Standardization (ISO) The OSI reference model breaks this approach into layers. OSI Re fe re nc e Mo de l NIC Software Cable NIC Cable OSI Re fe re nc e Mo de l Layer 7 - The Application Layer 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data Link 1 Physical ❑ It’s the S\w on our PCs that is used to represent a user interface to the network & so aids the user to make applications. Examples: Email (SMTP,POP3). Web browsers (HTTP). FTP. Telnet. Layer 6 - The Presentation Layer 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data Link 1 Physical This layer is responsible for presenting the data in the proper format. Examples: ASCII, AVI,JPG,…. Layer 5 - The Session Layer 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data Link 1 Physical Ensure that all information required for opening a session is available. Give orders for: establishment, management, and termination of the session. Layer 4 - The Transport Layer 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data Link 1 Physical Responsible for actual mechanism of: 1. Establishment of connection. 2. Management of connection: 2.1) Segmentation. 2.2) Sequencing. 2.3) End-to-end check. 2.4) Error detection &correction. 2.5) Flow control. 3. Termination of connection. Examples: TCP (transmission control protocol). UDP (User Datagram Protocol). Layer 3 - The Network Layer 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data Link 1 Physical Responsible for: 1. End-to-end delivery. 2. Logical addressing. EX: IPv4,IPv6,IPX,APPLETALK 3. Routing (choose the best path to destination.) EX: RIP,OSPF,IS-IS,EIGRP Layer 2 - The Data Link Layer 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data Link 1 Physical Responsible for: 1. Hop-to hop data delivery. 2. Hop-to-hop addressing (MAC Address in Ethernet). 3. Hop-to-hop error detection 4. Hop-to-hop flow control. Layer 1 - The Physical Layer 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data Link 1 Physical It’s responsible for all Physical properties of the network : 1. Cable length. 2. Cable type. 3. Bit rate. 4. Voltage levels. 5. H/W interface types. Summary Provides protocols for applications to be able to communicate Example: http, DNS, FTP, DNS ,SMTP. Responsible for data representation, Compression and encryption Establish, maintain and terminates sessions. Data segmentation, Sequencing, port addressing and flow control Protocols: TCP and UDP Routing, IP addressing , fragmentation and reassembly. Protocols: IP, ARP, RARP and ICMP MAC addressing, Access method, Framing and error checking. Protocols: Ethernet and ATM Carrying bits, cable length and signal value 2 TCP/I P Mo de l Layers with TCP/IP and OSI Model Compare OSI and TCP/IP model Compare OSI and TCP/IP model Point of view Similarities Differences OSI model TCP/IP model Consists of set of layers. Each layer performs function via protocol. Each layer adds header. Consists of 7 layers Consists of 4 layers Theoretical Practical More headers = more Less headers = less overhead. overhead. Encapsulation Data Link Header IP Header TCP Header HTTP Header Data Data Link Trailer Server HTTP Data Encapsulation – Process of adding control information as it passes down through the layered model. trailer The Communication Process - Decapsulation Data Link Header IP Header TCP Header HTTP Header Data Client HTTP Data trailer Data Link Trailer The Communication Process Protocol Data Unit (PDU) - The form that a piece of data takes at any layer. At each stage of the process, a PDU has a different name to reflect its new appearance. PDUs are named according to the protocols of the TCP/IP suite. ◦ ◦ ◦ ◦ ◦ Data - The general term for the PDU used at the Application layer Segment - Transport Layer PDU Packet - Internetwork Layer PDU Frame - Network Access Layer PDU Bits - A PDU used when physically transmitting data over the medium The Communication Process ❑ Physical layer → no header ❑ Data link layer→ source and destination MAC address ❑ Network layer→ source and destination IP address ❑ Transport layer→ source and destination Port address Addressing and Naming Schemes How labels in encapsulation headers are used to manage communication in data networks. Difference Between IP & MAC addresses MAC B IP: 1.1.1.2 MAC D IP: 2.2.2.1 MAC A IP: 1.1.1.1 MAC C IP: 1.1.1.3 MAC E IP: 2.2.2.2 What is the Address on my Ethernet NIC? IP and MAC addresses Point of view Definition Number of bits Representation Usage Layer Example IP address Logical = Can be changed Hardware address Physical = burned on NIC cannot be changed. 32 bits 48 bits Decimal. Hexadecimal. Communication between hosts in Communication between different LANs hosts in the same LANs Network layer Data link layer 190.10.120.1 F1.2C.33.2D.E5.23 Network devices capabilities Router Switch Bridge ‫‪Summary‬‬ ‫ توفر بروتوكوالت للتواصل بين التطبيقات ) ‪( HTTP, DHCP, DNS‬‬ ‫ مسئولة عن تمثيل البيانات و ضغطها وتشفيرها‬ ‫ انشاء قناة اتصال و المحافظة عليها خالل االتصال وانهاؤها‪.‬‬ ‫ تقسيم البيانات و ترقيمها و عنونتها بــ ‪Port address‬‬ ‫ التوجيه ‪ + IP addressing +‬التقسيم و التجميع‬ ‫ التحويل ‪ + MAC addressing +‬طريقة الوصول ‪Access method‬‬ ‫ نقل البيانات‬ THANKS! Best Regards!