CS100 Lecture Notes - Lecture 2: Digital Subscriber Line, Physical Layer, Communications Protocol
30 Oct 2017
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Document Summary
Module 2. 1 basic communication: the internet (biggest computer network, syncornous (happens in real time, example having a conversation with your friend) vs. Asyncronous (happens after, how all of the internet works) communication: communication -> messages. When message arrives it goes from low layers of communication to high layers. When message is sent it goes from high layers of communication down to low layers. Higher layers usually mean the same thing. Best way to thing of a computer protocol is to think about a form. Module 2. 2 physical layer (lowest payer: communication over the internet (computer network, different physical layers: ethernet, phone, adsl and cable modems, wifi, cellular (3g/lte, ethernet: Connection device requires unique identifies mac (media access control) address. Cable grades and speeds: if one device or cable is slower, it may slow down entire communication rate: phone, adsl, and cable modems. Internet used to be connected through the phone modem.
