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1.3.2a modelos de referencia


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Los Modeos de Referencia de arquitecturas de red OSI y TCP/IP

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1.3.2a modelos de referencia

  1. 1. Conceptos PreviosWilliam StallingsData and Computer Communications
  2. 2. OSI - The ModelA layer modelEach layer performs a subset of the required communication functionsEach layer relies on the next lower layer to perform more primitive functionsEach layer provides services to the next higher layerChanges in one layer should not require changes in other layers
  3. 3. The OSI Environment
  4. 4. OSI as Framework forStandardization
  5. 5. Layer Specific Standards
  6. 6. Elements of StandardizationProtocol specification Operates between the same layer on two systems May involve different operating system Protocol specification must be precise Format of data units Semantics of all fields allowable sequence of PCUsService definition Functional description of what is providedAddressing Referenced by SAPs
  7. 7. OSI Layers (1)Physical Physical interface between devices Mechanical Electrical Functional ProceduralData Link Means of activating, maintaining and deactivating a reliable link Error detection and control Higher layers may assume error free transmission
  8. 8. OSI Layers (2)Network Transport of information Higher layers do not need to know about underlying technology Not needed on direct linksTransport Exchange of data between end systems Error free In sequence No losses No duplicates Quality of service
  9. 9. OSI Layers (3)Session Control of dialogues between applications Dialogue discipline Grouping RecoveryPresentation Data formats and coding Data compression EncryptionApplication Means for applications to access OSI environment
  10. 10. Use of a Relay
  11. 11. TCP/IP Protocol SuiteDominant commercial protocol architectureSpecified and extensively used before OSIDeveloped by research funded US Department of DefenseUsed by the Internet
  12. 12. TCP/IP Protocol Architecture(1)Application Layer Communication between processes or applicationsEnd to end or transport layer (TCP/UDP/…) End to end transfer of data May include reliability mechanism (TCP) Hides detail of underlying networkInternet Layer (IP) Routing of data
  13. 13. TCP/IP Protocol Architecture(2)Network Layer Logical interface between end system and networkPhysical Layer Transmission medium Signal rate and encoding
  14. 14. PDUs in TCP/IP
  15. 15. Some Protocols in TCP/IP Suite