Three-Layer Model Distributed data communications involves three primary components: –Networks...
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Three-Layer Model • Distributed data communications involves three primary components: – Networks – Computers – Applications • Three corresponding layers – Network access layer – Transport layer – Application
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Transcript of Three-Layer Model Distributed data communications involves three primary components: –Networks...
Three-Layer Model
• Distributed data communications involves three primary components:– Networks– Computers– Applications
• Three corresponding layers– Network access layer– Transport layer– Application layer
Data Transmission
• Application layer creates data block• Transport layer appends header to create PDU (protocol data unit)
– Destination SAP, Sequence #, Error-Detection Code• Network layer appends another header
– Destination computer, facilities (e.g. “priority”)
Protocols in a Simplified Architecture
Operation of TCP/IP
TCP & UDP
IP Headers
Operation of TCP/IP: Action at the Sender
Operation of TCP/IP: Action at the Router
Operation of TCP/IP: Action at the Receiver
OSI
• Open Systems Interconnection
• Developed by ISO
• Contains seven layers
The OSI Environment
TCP/IP - OSI Comparison
