OSI layer by cisco

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OSI layer by cisco

  1. 1. OSI Reference Model Presented by Muktianto
  2. 2. OSI Layer Overview
  3. 3. Why a Layered Network Model? <ul><li>Reduces complexity </li></ul><ul><li>Standardizes interfaces </li></ul><ul><li>Facilitates modular engineering </li></ul><ul><li>Ensures interoperable technology </li></ul><ul><li>Accelerates evolution </li></ul><ul><li>Simplifies teaching and learning </li></ul>Application Presentation Session Transport Network Data Link Physical 1 2 3 4 5 6 7
  4. 4. Layer Functions Application Presentation Session Transport Network Data Link Physical 1 2 3 4 5 6 7 Network processes to applications Data representation Inter host communication End-to-end connections Addresses and best path Access to media Binary transmission
  5. 5. Peer-to-Peer Communication Physical Data Link Network Transport Session Presentation Application Physical Data Link Network Transport Session Presentation Application segment packet frame bit
  6. 6. Data Encapsulation Application Presentation Session Transport Network Data Link Physical Host A Application Presentation Session Transport Network Data Link Physical Host B Data Network Header Data Frame Frame Header Trailer Network Header Data 010010011010101
  7. 7. Upper Layer Overview
  8. 8. Application Layer Word Processing Spreadsheet Database Design/Manufacturing Project Planning Others Browser Filezila Ms. Outlook Computer Application Electronic Mail File Transfer Remote Access Client/Server Process Network Management Others Network Application Electronic Data Interchange World Wide Web E-Mail Gateways Special-Interest Bulletin Boards Financial Transaction Services Internet Navigation Utilities Conferencing (Video, Voice, Data) Others Internetwork Apps Internetwork application can extend beyond the enterprise
  9. 9. Presentation Layer <ul><li>Text </li></ul><ul><li>Data </li></ul><ul><ul><li>ASCII </li></ul></ul><ul><ul><li>EBCDIC </li></ul></ul><ul><ul><li>Encrypted </li></ul></ul><ul><li>Graphics </li></ul><ul><li>Visual Images </li></ul><ul><ul><li>PICT </li></ul></ul><ul><ul><li>TIFF </li></ul></ul><ul><ul><li>JPEG </li></ul></ul><ul><ul><li>GIF </li></ul></ul><ul><li>Sound </li></ul><ul><li>Video </li></ul><ul><ul><li>MIDI </li></ul></ul><ul><ul><li>MPEG </li></ul></ul><ul><ul><li>Quick Time </li></ul></ul>Provides code formatting and conversion for applications
  10. 10. Session Layer Network File System (NFS) Structured Query Language (SQL) Remote-Procedure Call (RPC) X Window System AppleTalk Session Protocol (ASP) DNA Session Control Protocol (SCP) Service Request Service Reply Coordinates applications as they interact on different hosts
  11. 11. Transport Layer Overview
  12. 12. Transport Layer <ul><li>Segments upper-layer applications </li></ul><ul><li>Establishes an end-to-end connection </li></ul><ul><li>Sends segments from one end host to another </li></ul><ul><li>Optionally, ensures data reliability </li></ul>
  13. 13. Segment Upper-Layer Applications Application Presentation Session Transport segments share traffic stream Transport Application port Data Application port Data Application port Data Electronic Mail File Transfer Terminal Session
  14. 14. Establishes Connection SENDER RECEIVER Synchronize Negotiate Connection Synchronize Acknowledge Connection Established Negotiate Connection (Send Segments)
  15. 15. Sends Segments with Flow Control <ul><li>Buffer Full </li></ul><ul><ul><li>Process </li></ul></ul><ul><ul><li>Segments </li></ul></ul><ul><li>Buffer OK </li></ul>Stop SENDER RECEIVER Transmit Not Ready Ready Resume Transmission Go
  16. 16. Reliability with Windowing Send 1 Window size = 1 SENDER RECEIVER Send 2 Send 3 Recv 1 Ack 2 Recv 2 Ack 3 Send 1 Window size = 3 SENDER RECEIVER Send 2 Send 3 Recv 1 Recv 2 Recv 3 Ack 4 Send 4
  17. 17. Network Layer Overview
  18. 18. Network Layer: Path Determination Layer 3 functions to find the best path through the internetwork Which Path?
  19. 19. Network Layer: Communicate Path Addresses represent the path of media connections 1 2 3 4 5 6 7 8 9 10 11
  20. 20. Addressing: Network and Host <ul><li>Network address - Path part used by the router </li></ul><ul><li>Host address - Specific port or device on the network </li></ul>1.1 2.1 3.1 1.2 1.3 Network Host 1 1 2 3 2 1 3 1
  21. 21. Routing Uses Network Addresses <ul><li>Network portion of address used to make path selections </li></ul><ul><li>Node portion of address refers to router port to the path </li></ul>Destination Network Direction and Router Port 1.0 2.0 3.0 1.1 2.1 3.1 1.0 3.1 3.0 2.1 2.0 1.1
  22. 22. Network-Layer Protocol Operations X Y A B C Application Presentation Session Transport Network Data Link Physical X Network Data Link Physical Network Data Link Physical Network Data Link Physical Application Presentation Session Transport Network Data Link Physical Y A B C Each router provides its services to support upper-layer functions
  23. 23. Physical and Data Link Overview
  24. 24. Physical and Data-Link Types Data Link (frames) Physical (bits, signals, clocking) E t h e r n e t 802.2 LLC 8 0 2 . 3 8 0 2 . 5 F D D I Dial on Demand SDLC HDLC X.25 Frame Relay ISDN PPP V.24 EIA/TIA-232 G.703 V.35 EIA/TIA-449 EIA-530 HSSI LAN WAN Separate physical and data link layers for LAN and WAN
  25. 25. LAN Data Link Sublayers Network Data Link Physical LLC MAC Logical Link Control Media Access Control MAC Frame 802.2 LLC Packet or Datagram <ul><li>LLC refers upward to higher-layer software functions </li></ul><ul><li>MAC refers downward to lower-layer hardware functions </li></ul>
  26. 26. Physical and Logical Addressing 0000.0c12.3456
  27. 27. MAC Address Vendor Code Serial Number 0000.0c12.3456 ROM RAM MAC address is burned into ROM on a network interface card 24 bits 24 bits
  28. 28. Finding the MAC Address Broadcast Host Z MAC ? Host Z ARP Request Host Y Host Z Host Y MAC Host Z MAC ARP Reply Example 1 : TCP/IP destination local Broadcast Host Z MAC ? Host Z ARP Request Host Y Host Z Host Y MAC Router MAC ARP Reply Example 2 : TCP/IP destination not local Router A Routing Table: Net for Host Z <ul><li>An example: TCP/IP Address Resolution Protocol (ARP) </li></ul><ul><li>ARP finds the MAC address for a data-link connection </li></ul>
  29. 29. WAN Technology Overview SDLC HDLC LAPB PPP X.25 Frame Relay ISDN
  30. 30. Physical Layer: WAN EIA/TIA-232 V.35 X.21 HSSI others (Modem) <ul><li>DTE </li></ul><ul><li>Data Terminal Equipment </li></ul><ul><ul><li>End of the user’s device on the WAN link </li></ul></ul><ul><li>DCE </li></ul><ul><li>Data Circuit-Terminating Equipment </li></ul><ul><ul><li>End of the WAN provider’s </li></ul></ul><ul><ul><li>side of the communication facility </li></ul></ul>
  31. 31. Data Link Layer: WAN Protocols (Modem) (Modem) <ul><li>SDLC - Synchronous Data Link Control </li></ul><ul><li>HDLC - High-Level Data Link Control </li></ul><ul><li>LAPB - Link Access Procedure Balanced </li></ul><ul><li>Frame Relay - Simplified version of HDLC framing </li></ul><ul><li>PPP - Point-to-point Protocol </li></ul><ul><li>X.25 - Packet level protocol (PLP) </li></ul><ul><li>ISDN - Integrated Services Digital Network (data-link signaling) </li></ul>
  32. 32. End Of Session

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