ENG EC 441 Lecture Notes - Lecture 3: Wi-Fi, Physical Layer, Packet Switching

• School: Boston University
• Department: Electrical & Computer Engineering
• Course: ENG EC 441
• Professor: Jeffrey Carruthers

Document Summary

Service models: each layer provides its service by, network layer is a mixed implementation of hardware and software, internet protocol stack = internet protocols of various layers. Using services of the layer directly below it: application layer. App in one end system uses protocol to exchange packets of info with app in another end system. Http protocol - provides for web document request and transfer. Smtp - provides for the transfer of e-mail messages. Ftp - provides for the transfer of files between two end systems. Dns (domain name system) - translation of human-friendly names of internet end systems to 32-bit network address: transport layer. Types: provides a connection-oriented service to its applications guarantees delivery of messages to destination and flow control (sender/receiver speed matching) Breaks long messages into shorted segments for congestion-control mechanism. Udp - provides a connectionless service to its applications: network layer/ ip layer. Receives segment and a destination address from transport layer.