Internet protocols.html (2494B)
1 <?xml version="1.0" encoding="UTF-8"?> 2 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 3 <html><head><link rel="stylesheet" type="text/css" href="sitewide.css"><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/><meta name="exporter-version" content="Evernote Mac 6.13.3 (455969)"/><meta name="altitude" content="-1.514543652534485"/><meta name="author" content="Alex Balgavy"/><meta name="created" content="2018-01-10 2:27:59 PM +0000"/><meta name="latitude" content="52.33314904223889"/><meta name="longitude" content="4.865572894879212"/><meta name="source" content="desktop.mac"/><meta name="updated" content="2018-01-10 2:31:22 PM +0000"/><title>Internet protocols</title></head><body><div>Protocols — rules to communicate over network</div><ul><li>TCPIIP on ARPANET in 1982</li><li>works locally (LAN) & on network</li><li>various models of communication, mainly client/server, but also peer-to-peer and others.</li></ul><div><br/></div>IP (internet protocol):<br/><ul><li>address in IPv4 is 32 bits<br/></li><li>associated with max 1 device at a time<br/></li><li>written as 4 dot-separated bytes<br/></li><li>transfers data packets from source to destination (like postal service)<br/></li><li>packets created by IP software contain:<br/></li><ul><li>header with source/destination address, length, etc.<br/></li><li>data<br/></li></ul></ul><div>TCP (transmission control protocol)</div><ul><li>provides guarantee that packet is delivered</li><li>provides 2-way communication</li><li>analogy: telephone status report</li><li>adds ports (numbers) representing destination process on destination computer (with some being standard)</li><li>higher-level protocols like SMTP, FTP, HTTP are built on top of this</li></ul><div><br/></div><div>UDP (user datagram protocol):</div><div><ul><li>like TCP</li><ul><li>builds IP</li><li>provides ports</li></ul><li>unlike TCP</li><ul><li>no connection concept</li><li>no transmission guarantee</li></ul><li>UDP is lightweight, better for one-time messages</li></ul><div><br/></div></div><div>DNS (domain name service)</div><div><ul><li>“phone book”</li><li>maps IP to hostnames (www.example.org)</li><li>top-level domain is the last part (.com, .org, . edu, etc.)</li></ul><div><br/></div></div><div>Analogy: IP is a telephone network, TCP is a conversation, UDP is a voicemail message, DNS is the yellow pages/directory assistance</div></body></html>