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Unformatted text preview: nough information to allow Art good performance
but not so much that small changes in one layer need changes to but other layers ISO OSI 7-Layer Model No very successful in practice (why?), more of a theoretical No interest only But have helped to shape the design of “real” protocol stacks But How is it different from the Internet protocol stack ? How Some terminology
Service access point (SAP) Service
interface between an upper layer and a lower layer interface Protocol data units (PDUs) Protocol
packets exchanged between peer entities packets Service data units (SDUs) Service
packets handed to a lower layer by an upper layer packets PDU = SDU + optional header or trailer PDU Example Example
letter transfer service letter protocol data unit between customers = letter protocol service data unit for postal service = letter service protocol data unit = mailbag (aggregation of letters) protocol (what is the SDU header?) (what Physical layer
Moves bits between physically connected end-systems Moves Standard prescribes Standard
coding scheme to represent a bit coding shapes and sizes of connectors shapes bit-level synchronization bit-level Postal network Postal
technology for moving letters from one point to another (trains, technology planes, vans, bicycles, ships…) Internet Internet
technology to move bits on a wire, wireless link, satelli...
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This note was uploaded on 12/08/2010 for the course IEG IEG3310 taught by Professor Wingc.lau during the Spring '10 term at CUHK.
- Spring '10