{"id":358,"date":"2020-04-06T08:12:56","date_gmt":"2020-04-06T06:12:56","guid":{"rendered":"http:\/\/tech.sosthe.sk\/?p=358"},"modified":"2020-04-06T22:43:35","modified_gmt":"2020-04-06T20:43:35","slug":"4-8-unicast-broadcast-multicast-a-anycast","status":"publish","type":"post","link":"http:\/\/tech.sosthe.sk\/index.php\/2020\/04\/06\/4-8-unicast-broadcast-multicast-a-anycast\/","title":{"rendered":"4.12. Unicast, broadcast, multicast a anycast."},"content":{"rendered":"<p>T\u00e1to kapitolka sl\u00fa\u017ei iba na vysvetlenie \u0161tyroch smerovac\u00edch sch\u00e9m:<\/p>\n<ul>\n<li><strong>Unicast<\/strong>\u00a0je tak\u00e1 smerovacia sch\u00e9ma, pri ktorej datagramy vych\u00e1dzaj\u00face od zdroja d\u00e1t smeruj\u00fa v\u017edy k jedinej presne ur\u010denej cie\u013eovej stanici. Unicast smerovanie je vy\u017eadovan\u00e9 napr\u00edklad protokolom TCP, kedy mus\u00ed komunik\u00e1cia prebieha\u0165 v\u017edy len medzi dvojicou stan\u00edc.<\/li>\n<li><strong>Anycast<\/strong>\u00a0je smerovacia sch\u00e9ma, pri ktorej je viac potenci\u00e1lnych pr\u00edjemcov spr\u00e1vy, ale spr\u00e1va je doru\u010den\u00e1 iba jedn\u00e9mu z nich, obvykle najbli\u017e\u0161iemu. Anycast sa vyu\u017e\u00edva napr\u00edklad pri komunik\u00e1cii s kore\u0148ov\u00fdmi DNS servermi pr\u00edpadne aj niektor\u00fdmi TLD DNS servermi. Ako vieme, existuje iba 13 IPv4 adries kore\u0148ov\u00fdch DNS serverov, ale re\u00e1lne je ka\u017ed\u00e1 z t\u00fdchto IPv4 adries pou\u017eit\u00e1 pre viacer\u00e9 stanice. Po\u017eiadavka na kore\u0148ov\u00fd DNS server teda m\u00f4\u017ee pr\u00eds\u0165 na \u013eubovo\u013en\u00fd (jeden) z t\u00fdchto serverov.<\/li>\n<li><strong>Broadcast<\/strong>\u00a0je smerovacia sch\u00e9ma, ktor\u00e1 zaru\u010duje doru\u010denie odoslanej spr\u00e1vy v\u0161etk\u00fdm uzlom, \u010di podsie\u0165am. Broadcast sa pou\u017e\u00edva napr\u00edklad pri protokole OSPF, ktor\u00fd pred samotn\u00fdm spusten\u00edm Dijkstrovho algoritmu potrebuje rozosla\u0165 od ka\u017ed\u00e9ho routra ku ka\u017ed\u00e9mu routru inform\u00e1ciu o lok\u00e1lnych cen\u00e1ch spojov (hr\u00e1n). Pojem broadcast sa pou\u017e\u00edva aj na ozna\u010denie spr\u00e1vy vo vn\u00fatri siete ur\u010denej pre v\u0161etky stanice v sieti. Na tomto princ\u00edpe funguje napr\u00edklad protokol DHCP alebo ARP (bude vysvetlen\u00fd pri spojovej vrstve). Na aplika\u010dnej vrstve funguje na princ\u00edpe broadcastu napr\u00edklad peer-to-peer protokol Gnutella.<\/li>\n<li><strong>Multicast<\/strong>\u00a0je smerovacia sch\u00e9ma, ktor\u00e1 rozosiela spr\u00e1vy ka\u017ed\u00e9mu, kto je prihl\u00e1sen\u00fd v danej multicastovej skupine. Multicast je ve\u013emi podobn\u00fd broadcastu, preto\u017ee zabezpe\u010duje, aby rozosielan\u00e9 spr\u00e1vy prij\u00edmali v\u0161etky stanice a routre, ktor\u00e9 ich prij\u00edma\u0165 chc\u00fa, ale na rozdiel od broadcastu zabezpe\u010duje aj to, aby stanice, a ak to nebr\u00e1ni prvej podmienke aj routre, neprij\u00edmali rozosielan\u00e9 spr\u00e1vy, ak si to nepraj\u00fa. Multicast pou\u017e\u00edvaj\u00fa hlavne r\u00e1di\u00e1 a telev\u00edzie na streamovan\u00e9 vysielanie cez internet. Je v\u0161ak ve\u013emi u\u017eito\u010dn\u00fd aj napr\u00edklad pre videokonferencie, gridov\u00e9 v\u00fdpo\u010dty, sie\u0165ov\u00e9 hry alebo rozosielanie aktualiz\u00e1ci\u00ed programov.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>T\u00e1to kapitolka sl\u00fa\u017ei iba na vysvetlenie \u0161tyroch smerovac\u00edch sch\u00e9m: Unicast\u00a0je tak\u00e1 smerovacia sch\u00e9ma, pri ktorej datagramy vych\u00e1dzaj\u00face od zdroja d\u00e1t smeruj\u00fa v\u017edy k jedinej presne&hellip;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9],"tags":[],"_links":{"self":[{"href":"http:\/\/tech.sosthe.sk\/index.php\/wp-json\/wp\/v2\/posts\/358"}],"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=358"}],"version-history":[{"count":2,"href":"http:\/\/tech.sosthe.sk\/index.php\/wp-json\/wp\/v2\/posts\/358\/revisions"}],"predecessor-version":[{"id":536,"href":"http:\/\/tech.sosthe.sk\/index.php\/wp-json\/wp\/v2\/posts\/358\/revisions\/536"}],"wp:attachment":[{"href":"http:\/\/tech.sosthe.sk\/index.php\/wp-json\/wp\/v2\/media?parent=358"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/tech.sosthe.sk\/index.php\/wp-json\/wp\/v2\/categories?post=358"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/tech.sosthe.sk\/index.php\/wp-json\/wp\/v2\/tags?post=358"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}