International Standards Organization Open Systems Interconnect OSI Reference Slides: 7 Download presentation International Standards Organization Open Systems Interconnect (OSI) Reference Model Networks: OSI Reference Model 1 Application A Application B Application Layer Presentation Layer Session Layer Transport Layer Communication Network Transport Layer Network Layer Data Link Layer Physical Layer Copyright © 2000 The Mc. Graw Hill Companies Electrical and/or Optical Signals Leon-Garcia & Widjaja: Communication Networks: OSI Reference Model Figure 2. 6 2 Leon-Garcia & Widjaja: Communication Networks Copyright © 2000 The Mc. Graw Hill Companies Application A data Transport Layer data Network Layer Physical Layer Presentation Layer ph data Session Layer Application Layer ah data Presentation Layer Data Link Layer Application B data Application Layer sh Session Layer th Transport Layer data dt Figure 2. 9 data bits Networks: OSI Reference Model Network Layer nh dh Data Link Layer Physical Layer 3 HTTP Request Header contains source and destination port numbers Header contains source and destination IP addresses; transport protocol type Header contains source and destination physical addresses; network protocol type TCP Header IP Header Frame Check Sequence Ethernet Header Copyright © 2000 The Mc. Graw Hill Companies Leon-Garcia & Widjaja: Communication Networks: OSI Reference Model Figure 2. 15 4 OSI versus TCP/IP Figure 1 -21. The TCP/IP reference model. Networks: OSI Reference Model 5 OSI versus TCP/IP DCC 6 th Ed. , W. Stallings Figure 1. 11 Networks: OSI Reference Model 6 Seven OSI Layers Networks: OSI Reference Model 7