Network Layered Models Rroosend


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Network Layered Models Explained

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Network Layered Models Rroosend

  1. 1. NetworkLayered Models(CCNA1-Exploration)<br />Rob Roosendaal, Lecturer<br />INHolland University<br />Regional Cisco Networking Academy<br />
  2. 2. Reasons to use Layers<br />Easier to understand the different tasks of data communication<br />Easier to replace only one part of the whole data communication task stack (BNC / UTP / Fiber / Radio)<br />Easier to study all the roles of data communication (Cisco says)<br /><br />2<br />
  3. 3. Different Models<br />OSI Model<br />Developed by Open Systems Interconnection (OSI)<br />7 Layers<br />Theoretical base<br /><br />3<br />TCP/IP Model<br />De-facto Model developed by DARPA for millitairy computer networks<br />4 Layers<br />Practical base<br />
  4. 4. The OSI Model Layers<br />7 Application Layer<br />6 Presentation Layer<br />5 Session Layer<br />4 Transport Layer<br />3 Network Layer<br />2 Data Link Layer<br />1 Physical Layer<br />All<br />People<br />Seem<br />To<br />Need<br />Data<br />Processing<br /><br />4<br /><ul><li>Anderson
  5. 5. Pamela
  6. 6. See
  7. 7. To
  8. 8. Need
  9. 9. Do
  10. 10. People
  11. 11. Again
  12. 12. People
  13. 13. Sales
  14. 14. Trust
  15. 15. Not
  16. 16. Do
  17. 17. Please</li></li></ul><li>The Application Layer (OSI)<br />Closest to the end user<br />Application layers interact directly with application<br />Users interact directly with application<br />Application layer functions:<br />communication partners<br />determining resource availability<br />synchronizing communication<br />Examples: HTTP, FTP, SMTP<br /><br />5<br />
  18. 18. The Presentation Layer (OSI)<br />Establishes context between Application Layer entities<br />Different syntax and semantics<br />Independence from differences in data representation<br />Transforms data into form that application layer accept<br />Examples: <br />Convert EBCDIC-coded file to ASCII-coded file<br />Serializes objects and other data structures from and to XML<br /><br />6<br />
  19. 19. The Session Layer (OSI)<br />Controls the connections between computers<br />Full-duplex, half-duplex, or simplex operation<br />Checkpointing, adjournment, termination, and restart procedures<br />Graceful close of sessions<br />Implemented explicitly in application environments that use remote procedure calls<br /><br />7<br />
  20. 20. The Transport Layer (OSI)<br />Reliable data transfer services to the upper layers using flow control, segmentation/desegmentation, error control, windowing<br />Five classes of connection-mode transport protocols<br />Class/TP 0 for less reliable to class/TP 4 for most reliable<br /><br />8<br />
  21. 21. The Network Layer (OSI)<br />Functional and procedural means of transferring variable length data sequences<br />Performs network routing functions. Routers operate at this layer using a logical addressing scheme<br />Layer management protocols (ISO 7498/4)<br />Routing protocols<br />Multicast group management<br />Network Layer information and error<br />Network Layer address assignment<br /><br />9<br />
  22. 22. The Data Link Layer (OSI)<br />Functional and procedural means to transfer data between network entities and to detect and possibly correct errors that may occur in the Physical Layer<br />Point-to-Point Protocol (PPP)<br />Manages the interaction of devices with a shared medium (Media Access Control sublayer)<br />Manages addressing and multiplexing on multiaccess media (Logical Link Control sublayer)<br /><br />10<br />
  23. 23. The Physical Layer (OSI)<br />Electrical and physical specifications for devices (layout of pins, voltages, cable specifications)<br />Establishment and termination of a connection to a communications medium.<br />Modulation from and to the signals transmitted over a communications channel (coper, fiber, radio, …). <br />Ethernet incorporates both this layer and the Data Link Layer.<br /><br />11<br />
  24. 24. Internet Protocol Suite (TCP/IP)<br /><br />12<br />
  25. 25. The Application Layer (TCP/IP)<br />Roughly equivalent to the OSI Application, Presentation and Session layers<br />Support the applications and utilities that are the Internet<br />Focuses on network services, APIs, utilities, and operating system environments<br />Examples: DHCP, DNS, HTTP, IRC, POP, SMTP, SSH <br /><br />13<br />
  26. 26. The Transport Layer (TCP/IP)<br />Roughly equivalent to the OSI Transport layer<br />Port identifier in TCP/UDP messages<br />Port identifier and IP address together form a socket<br />Uniquely identified on the Internet by the four-tuplesource port and address, destination port and address<br />TCP provides connection-oriented communication<br />UDP provides connectionless communication<br /><br />14<br />
  27. 27. The Internet Layer (TCP/IP)<br />Roughly equivalent to the OSI Network Layer<br />Provides connectionless transport service across the network<br />Does not provide a mechanism for flow control<br />Examples: IP (IPv4, IPv6), ICMP, ICMPv6, IPsec<br /><br />15<br />
  28. 28. The Network Interface Layer (TCP/IP)<br />Roughly equivalent to the OSI Data Link and Physical Layers<br />Operates over nearly any underlying local or wide area network technology<br />Particularly relevant: <br />The Serial Line Internet Protocol (SLIP, RFC 1055) <br />Point-to-Point Protocol (PPP, RFC 1661)<br />Examples: ARP, RARP, SLIP, PPP, MAC<br /><br />16<br />
  29. 29. TCP/IP versus OSI<br />TCP/IP<br />OSI<br /><br />17<br />Application<br />Application<br />Presentation<br />Session<br />Transport<br />Transport<br />Network<br />Internet<br />Network Interface<br />Data Link<br />Physical<br />