CS100 Lecture Notes - Lecture 8: Asymmetric Digital Subscriber Line, Unique Identifier, International Mobile Station Equipment Identity

• School: University of Waterloo
• Department: Computer Science
• Course: CS100
• Professor: Kevin Harrigan

Document Summary

2. 2 physical layer lowest layer of communication. Communicates over a physical wire or ethernet cable. Requires a unique identifier: mac (media access control) A(cid:374)alogy: (cid:862)party ce(cid:374)ario(cid:863: de(cid:448)ice (cid:449)o(cid:374)"t start (cid:862)talki(cid:374)g(cid:863) u(cid:374)til others are do(cid:374)e talki(cid:374)g or (cid:449)he(cid:374) there is a gap. Slower connection devices or ethernet cables can slow down entire communication chain. Communication with a modem occurs b/t two devices. Modern equivalents to traditional modems are cable modems and adsl modems (over a phone line) Cable modems & adsl: use non-vocal frequencies to transmit info (allows higher capacities and faster speeds) Traditional/phone modems: use vocal frequencies to transmit info. Adsl (asymmetric digital subscriber line: do(cid:449)(cid:374)load speed is (cid:373)uch faster tha(cid:374) upload speed; he(cid:374)ce (cid:862)asy(cid:373)(cid:373)etric(cid:863) Wifi requires an access point: connects to internet through wifi, broadcasts a (cid:862)(cid:374)a(cid:373)e(cid:863, provides additional security (i. e. username, password, extra encryption) Have different speeds and different protocols multiple standards. Very similar to ethernet process (cid:862)party(cid:863) sce(cid:374)ario: (cid:449)aiti(cid:374)g for the gap to talk.