{"id":266,"date":"2020-04-05T23:00:47","date_gmt":"2020-04-05T21:00:47","guid":{"rendered":"http:\/\/tech.sosthe.sk\/?p=266"},"modified":"2020-04-06T16:45:38","modified_gmt":"2020-04-06T14:45:38","slug":"1-6-jadro-internetu","status":"publish","type":"post","link":"http:\/\/tech.sosthe.sk\/index.php\/2020\/04\/05\/1-6-jadro-internetu\/","title":{"rendered":"1.6.\u2002Jadro internetu"},"content":{"rendered":"<p>Jadro internetu tvor\u00ed sie\u0165 routrov (po slovensky smerova\u010dov) prev\u00e1dzkovan\u00fdch providermi, ktorej \u00falohou je umo\u017eni\u0165 komunik\u00e1ciu medzi \u013eubovo\u013en\u00fdmi dvoma koncov\u00fdmi zariadeniami. Prv\u00e9 telef\u00f3nne spolo\u010dnosti vyu\u017e\u00edvali na spojenie \u013eubovo\u013en\u00fdch dvoch telef\u00f3nov oper\u00e1torov (prep\u00e1jate\u013eov), ktor\u00ed priamym napojen\u00edm jedn\u00e9ho kan\u00e1lu v prenosovom k\u00e1bli vytvorili okruh, ktor\u00fd priamo spojil oboch telefonistov. Tento princ\u00edp ostal v telef\u00f3nnych \u00fastredniach dodnes, aj ke\u010f sa u\u017e \u013eudsk\u00ed oper\u00e1tori nepou\u017e\u00edvaj\u00fa. Tento princ\u00edp prep\u00e1jania nazveme\u00a0<strong>prep\u00ednanie okruhov<\/strong>.<\/p>\n<h3>1.6.1\u2002 Prep\u00ednanie okruhov<\/h3>\n<p>Po vytvoren\u00ed okruhu medzi koncov\u00fdmi stanicami, s\u00fa v\u0161etky zdroje na ceste vyhraden\u00e9 tejto komunik\u00e1cii aj v pr\u00edpade, \u017ee nikto z \u00fa\u010dastn\u00edkov okruhu pr\u00e1ve nevysiela. Na to, aby bolo umo\u017enen\u00e9 komunikova\u0165 aj ostatn\u00fdm, ktor\u00ed s\u00fa napojen\u00ed na niektor\u00fa \u00fastred\u0148u, sa pou\u017e\u00edva rozk\u00faskovanie pripojenia na dan\u00fd po\u010det kan\u00e1lov (spojen\u00ed). Rozk\u00faskovanie sa rob\u00ed bu\u010f frekven\u010dn\u00fdm delen\u00edm (FDM) alebo \u010dasov\u00fdm delen\u00edm (TDM).<\/p>\n<p>Pri\u00a0<strong>frekven\u010dnom delen\u00ed<\/strong>\u00a0m\u00e1 ka\u017ed\u00fd kan\u00e1l vyhraden\u00fd po cel\u00fd \u010das nejak\u00fd zlomok celkovej \u0161\u00edrky p\u00e1sma (interval frekvenci\u00ed v ktorom vysiela). Napr\u00edklad ak je \u0161\u00edrka prenosov\u00e9ho p\u00e1sma 100 kb\/s a dan\u00e9 spojenie je zdie\u013ean\u00e9 5 kan\u00e1lmi, tak ka\u017ed\u00fd z nich m\u00e1 k dispoz\u00edcii \u0161\u00edrku p\u00e1sma 20 kb\/s v \u013eubovo\u013enom \u010dase.<\/p>\n<p><strong>\u010casov\u00e9 delenie<\/strong>\u00a0poskytuje st\u00e1le dookola cel\u00fa \u0161\u00edrku p\u00e1sma postupne ka\u017ed\u00e9mu kan\u00e1lu na kr\u00e1tky \u010dasov\u00fd \u00fasek, t. j. ak je celkov\u00e1 \u0161\u00edrka p\u00e1sma 100 kB\/s, tak ka\u017ed\u00fd zo zdie\u013ean\u00fdch 5 kan\u00e1lov m\u00e1 k dispoz\u00edcii cel\u00fa \u0161\u00edrku p\u00e1sma 100 kB\/s, ale nie po cel\u00fd \u010das. Napr\u00edklad ak cyklus prep\u00ednania trv\u00e1 100 ms, tak povedzme prv\u00fd z kan\u00e1lov je akt\u00edvny od dan\u00e9ho \u010dasu iba v \u010dasoch 0-20 ms, 100-120 ms, 200-220 ms a tak \u010falej.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-267 size-full\" src=\"http:\/\/tech.sosthe.sk\/wp-content\/uploads\/2020\/04\/fig01_p01.gif\" alt=\"\" width=\"708\" height=\"357\" \/><\/p>\n<h3>1.6.2\u2002 Prep\u00ednanie riaden\u00e9 paketmi<\/h3>\n<p>V internete sa pou\u017e\u00edva\u00a0<strong>prep\u00ednanie riaden\u00e9 paketmi<\/strong>. Jeho ve\u013ekou v\u00fdhodou je to, \u017ee nenast\u00e1va situ\u00e1cia, \u017ee nejak\u00e9 spojenie m\u00e1 pridelen\u00e9 v\u0161etky zdroje iba pre seba a v danom \u010dase nepotrebuje vysiela\u0165 ani prij\u00edma\u0165 d\u00e1ta. Pri komunik\u00e1cii riadenej paketmi pou\u017e\u00edvatelia vyu\u017e\u00edvaj\u00fa zdroje vtedy, ke\u010f potrebuj\u00fa. Cenou za to je nutnos\u0165 rozdeli\u0165 odosielan\u00e9 d\u00e1ta na men\u0161ie k\u00fasky, takzvan\u00e9 pakety. Ka\u017ed\u00fd paket m\u00e1 k dispoz\u00edcii cel\u00fa \u0161\u00edrku p\u00e1sma. Pri prep\u00ednan\u00ed riadenom paketmi odpad\u00e1 nutnos\u0165 vytvorenia okruhu medzi koncov\u00fdmi stanicami pred samotn\u00fdm posielan\u00edm d\u00e1t, preto\u017ee ka\u017ed\u00fd paket so sebou nesie inform\u00e1ciu o tom, odkia\u013e a kam ide.<\/p>\n<p>Nev\u00fdhodou tohto pr\u00edstupu je, \u017ee po\u017eiadavky na zdroje m\u00f4\u017eu by\u0165 v\u00e4\u010d\u0161ie ako tieto zdroje zvl\u00e1dnu. Tieto zdroje s\u00fa potom zahlten\u00e9, \u010do m\u00f4\u017ee sp\u00f4sobi\u0165 zahodenie niektor\u00fdch paketov.<\/p>\n<p>Najv\u00e4\u010d\u0161ou v\u00fdhodou tohto pr\u00edstupu je mo\u017enos\u0165 komunik\u00e1cie v\u00e4\u010d\u0161ieho mno\u017estva zariaden\u00ed paralelne v porovnan\u00ed s prep\u00ednan\u00edm okruhov. D\u00f4vod je ten, \u017ee nedoch\u00e1dza k stavu, \u017ee zariadenie m\u00e1 pridelen\u00e9 spojenie a nevysiela ani neprij\u00edma (\u010do je ve\u013emi \u010dast\u00e9). V\u0161etky tieto \u201ehluch\u00e9 miesta\u201c tak m\u00f4\u017eu by\u0165 vyu\u017eit\u00e9 nov\u00fdmi zariadeniami.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Jadro internetu tvor\u00ed sie\u0165 routrov (po slovensky smerova\u010dov) prev\u00e1dzkovan\u00fdch providermi, ktorej \u00falohou je umo\u017eni\u0165 komunik\u00e1ciu medzi \u013eubovo\u013en\u00fdmi dvoma koncov\u00fdmi zariadeniami. Prv\u00e9 telef\u00f3nne spolo\u010dnosti vyu\u017e\u00edvali na&hellip;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6],"tags":[],"_links":{"self":[{"href":"http:\/\/tech.sosthe.sk\/index.php\/wp-json\/wp\/v2\/posts\/266"}],"collection":[{"href":"http:\/\/tech.sosthe.sk\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/tech.sosthe.sk\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/tech.sosthe.sk\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/tech.sosthe.sk\/index.php\/wp-json\/wp\/v2\/comments?post=266"}],"version-history":[{"count":2,"href":"http:\/\/tech.sosthe.sk\/index.php\/wp-json\/wp\/v2\/posts\/266\/revisions"}],"predecessor-version":[{"id":464,"href":"http:\/\/tech.sosthe.sk\/index.php\/wp-json\/wp\/v2\/posts\/266\/revisions\/464"}],"wp:attachment":[{"href":"http:\/\/tech.sosthe.sk\/index.php\/wp-json\/wp\/v2\/media?parent=266"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/tech.sosthe.sk\/index.php\/wp-json\/wp\/v2\/categories?post=266"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/tech.sosthe.sk\/index.php\/wp-json\/wp\/v2\/tags?post=266"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}