{"id":350,"date":"2020-04-06T08:10:01","date_gmt":"2020-04-06T06:10:01","guid":{"rendered":"http:\/\/tech.sosthe.sk\/?p=350"},"modified":"2020-04-06T22:42:19","modified_gmt":"2020-04-06T20:42:19","slug":"4-5-smerovacie-protokoly-vnutri-autonomnych-systemov","status":"publish","type":"post","link":"http:\/\/tech.sosthe.sk\/index.php\/2020\/04\/06\/4-5-smerovacie-protokoly-vnutri-autonomnych-systemov\/","title":{"rendered":"4.10. Smerovacie protokoly vn\u00fatri auton\u00f3mnych syst\u00e9mov"},"content":{"rendered":"<p>Smerovac\u00ed protokol vn\u00fatri auton\u00f3mnych syst\u00e9mov m\u00e1 za \u00falohu nastavi\u0165, ako bud\u00fa smerovan\u00e9 datagramy medzi jednotliv\u00fdmi sie\u0165ami v r\u00e1mci tohto auton\u00f3mneho syst\u00e9mu. Najzn\u00e1mej\u0161ie tak\u00e9to smerovacie protokoly s\u00fa RIP a OSPF. Pr\u00edbuzn\u00fd protokol k OSPF je IS-IS protokol (<a href=\"http:\/\/www.ietf.org\/rfc\/rfc1142.txt\">RFC 1142<\/a>). My sa bli\u017e\u0161ie pozrieme na prv\u00e9 dva.<\/p>\n<p>Smerovacie protokoly pre auton\u00f3mne syst\u00e9my sa niekedy naz\u00fdvaj\u00fa aj Interior Gateway Protocols (IGP).<\/p>\n<h3>4.10.1\u2002 RIP: Routing information protocol<\/h3>\n<p>verzia 1 :\u00a0<a href=\"http:\/\/www.ietf.org\/rfc\/rfc1058.txt\">RFC 1058<\/a>, verzia 2:\u00a0<a href=\"http:\/\/www.ietf.org\/rfc\/rfc2453.txt\">RFC 2453<\/a><\/p>\n<p>RIP je aplika\u010dn\u00fd protokol, ktor\u00fd pracuje ve\u013emi podobne ako teoretick\u00fd model DVA. V DVA sme pre jednoduchos\u0165 ako cenu uv\u00e1dzali cenu hrany medzi dvoma routrami. V RIP (aj v OSPF) sa uva\u017euj\u00fa ceny od routra k jednotliv\u00fdm sie\u0165am a podsie\u0165am. RIP ako cenu cesty od niektor\u00e9ho routra k cie\u013eovej sieti pova\u017euje po\u010det routrov (hop-ov), ktor\u00e9 sa na tejto ceste nach\u00e1dzaj\u00fa vr\u00e1tane samotn\u00e9ho routra. To znamen\u00e1, \u017ee cena cesty k sieti priamo napojenej na dan\u00fd router je rovn\u00e1 jednej. Maxim\u00e1lna cena cesty pre RIP je ur\u010den\u00e1 na 15 hop-ov, t\u00fdm p\u00e1dom by sa RIP vo v\u00e4\u010d\u0161\u00edch AS nemal pou\u017e\u00edva\u0165. V\u0161etky siete vo vzdialenosti viac ako 15 hopov s\u00fa vo vzdialenosti nekone\u010dno (zapisuje sa \u010d\u00edslom 16).<\/p>\n<p>V DVA routre zasielaj\u00fa svoje vektory vzdialenost\u00ed, ak sa zmen\u00ed cena lok\u00e1lnych spojen\u00ed. V RIP sa ceny lok\u00e1lnych spojen\u00ed (teda po\u010det hop-ov) menia iba pri odpojen\u00ed\/pripojen\u00ed. Namiesto tohto mechanizmu sa v RIP posielaj\u00fa vektory vzdialenost\u00ed (RIP inform\u00e1cie) ka\u017ed\u00fdch 30 sek\u00fand, aj ke\u010f sa ni\u010d nezmenilo. Tieto vektory maj\u00fa povolen\u00fdch maxim\u00e1lne 25 cie\u013eov\u00fdch siet\u00ed z vn\u00fatra AS. Ak router nedostane od svojho suseda \u017eiadne RIP inform\u00e1cie po dobu 180 sek\u00fand, je tento sused pova\u017eovan\u00fd za nedostupn\u00e9ho. RIP poskytuje aj mo\u017enos\u0165 vy\u017eiada\u0165 si RIP inform\u00e1cie od suseda cez RIP po\u017eiadavku.<\/p>\n<p>Ke\u010f\u017ee cena cesty sa r\u00e1ta ako po\u010det routrov na tejto ceste, m\u00f4\u017eeme poveda\u0165, \u017ee vzdialenos\u0165 susedn\u00fdch routrov je v\u017edy 1. Predpokladajme, \u017ee router A m\u00e1 v svojom vektore vzdialenost\u00ed cenu k sieti X 10 hopov cez router B. Ak od routra C pr\u00edde routru A RIP inform\u00e1cia, \u017ee router C m\u00e1 vzdialenos\u0165 k sieti X iba 5 hopov, tak router A si m\u00f4\u017ee zmeni\u0165 svoju vzdialenos\u0165 k sieti X na 5+1=6 hopov cez router C.<\/p>\n<p>Protokol RIP sa roz\u0161\u00edril v roku 1982 ako s\u00fa\u010das\u0165 BSD Unixu. Na komunik\u00e1ciu pou\u017e\u00edva UDP protokol a port 520. Ide teda o aplika\u010dn\u00fd protokol (pou\u017e\u00edvan\u00fd programom routed) na riadenie smerovacej tabu\u013eky v sie\u0165ovej vrstve.<\/p>\n<h3>4.10.2\u2002 OSPF: Open shortest path first<\/h3>\n<p>verzia 2:\u00a0<a href=\"http:\/\/www.ietf.org\/rfc\/rfc2328.txt\">RFC 2328<\/a><\/p>\n<p>OSPF je mlad\u0161\u00ed protokol ako RIP a m\u00e1 oproti nemu aj mnoho vylep\u0161en\u00ed. OSPF je zalo\u017een\u00fd na LSA algoritme, teda na kompletnej inform\u00e1cii o topol\u00f3gii siete, cene v\u0161etk\u00fdch hr\u00e1n a na Dijkstrovom algoritme, ktor\u00fd pre ka\u017ed\u00fd uzol vytv\u00e1ra strom najkrat\u0161\u00edch ciest k jednotliv\u00fdm sie\u0165am (nie k routrom ako v teoretickom modeli).<\/p>\n<p>Ceny jednotliv\u00fdch hr\u00e1n s\u00fa nastavovan\u00e9 sie\u0165ov\u00fdm administr\u00e1torom, nie riaden\u00e9 protokolom. Administr\u00e1tor si v\u0161ak m\u00f4\u017ee vybra\u0165, \u010di nastav\u00ed ceny hr\u00e1n na 1 alebo in\u00fa kon\u0161tantu, alebo sa bud\u00fa vypo\u010d\u00edtava\u0165 na z\u00e1klade prev\u00e1dzky \u010di aktu\u00e1lnej priepustnosti spojen\u00ed.<\/p>\n<p>Inform\u00e1cia o topol\u00f3gii siete sa z\u00edskava broadcastov\u00fdmi spr\u00e1vami aspo\u0148 raz za 30 min\u00fat. Spr\u00e1vy OSPF protokolu s\u00fa pren\u00e1\u0161an\u00e9 priamo v tele IP datagramov.<\/p>\n<p>OSPF prid\u00e1va oproti protokolu RIP \u010fal\u0161iu funkcionalitu.<\/p>\n<ul>\n<li>Umo\u017e\u0148uje autentifik\u00e1ciu OSPF spr\u00e1v. To znamen\u00e1, \u017ee iba spr\u00e1vy od routrov spravovan\u00fdch administr\u00e1torom dan\u00e9ho AS s\u00fa akceptovan\u00e9 a \u017eiaden \u00fato\u010dn\u00edk vo vn\u00fatri AS nem\u00f4\u017ee ovplyv\u0148ova\u0165 smerovac\u00ed algoritmus.<\/li>\n<li>Ak existuje viac ciest s rovnakou cenou, OSPF nevy\u017eaduje vybratie iba jednej z nich ako v origin\u00e1lnom Dijkstrovom algoritme. T\u00fdm p\u00e1dom sa m\u00f4\u017ee prev\u00e1dzka rozdeli\u0165 rovnomerne na obe cesty.<\/li>\n<li>Integrovan\u00e1 podpora pre multicastov\u00e9 smerovanie v roz\u0161\u00edren\u00ed MOSPF (<a href=\"http:\/\/www.ietf.org\/rfc\/rfc1584.txt\">RFC 1584<\/a>), ktor\u00e1 prid\u00e1va multicastov\u00e9 inform\u00e1cie do existuj\u00facich broadcastov\u00fdch inform\u00e1ci\u00ed o cen\u00e1ch hr\u00e1n.<\/li>\n<li>Podpora pre hierarchick\u00e9 smerovanie vo vn\u00fatri AS je asi najd\u00f4le\u017eitej\u0161\u00edm pr\u00ednosom tohto protokolu. O hierarchickom smerovan\u00ed viac v \u010fal\u0161ej kapitole. Pri hierarchickom smerovan\u00ed sa routre m\u00f4\u017eu organizova\u0165 do auton\u00f3mnych oblast\u00ed. V ka\u017edej oblasti be\u017e\u00ed nez\u00e1visl\u00e9 klasick\u00e9 OSPF smerovanie. Jednotliv\u00e9 oblasti s\u00fa prepojen\u00e9 cez hrani\u010dn\u00e9 routre oblast\u00ed, ktor\u00e9 tvoria chrbticov\u00fa oblas\u0165. Aby to nebolo jednoduch\u00e9, chrbticov\u00e1 oblas\u0165 m\u00f4\u017ee obsahova\u0165 aj routre, ktor\u00e9 nie s\u00fa s\u00fa\u010das\u0165ou \u017eiadnej z auton\u00f3mnych oblast\u00ed. Chrbticov\u00e1 oblas\u0165 je tie\u017e jedin\u00e1, ktor\u00e1 obsahuje aj br\u00e1ny na komunik\u00e1ciu s in\u00fdmi auton\u00f3mnymi syst\u00e9mami.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Smerovac\u00ed protokol vn\u00fatri auton\u00f3mnych syst\u00e9mov m\u00e1 za \u00falohu nastavi\u0165, ako bud\u00fa smerovan\u00e9 datagramy medzi jednotliv\u00fdmi sie\u0165ami v r\u00e1mci tohto auton\u00f3mneho syst\u00e9mu. Najzn\u00e1mej\u0161ie tak\u00e9to smerovacie protokoly&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\/350"}],"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=350"}],"version-history":[{"count":3,"href":"http:\/\/tech.sosthe.sk\/index.php\/wp-json\/wp\/v2\/posts\/350\/revisions"}],"predecessor-version":[{"id":534,"href":"http:\/\/tech.sosthe.sk\/index.php\/wp-json\/wp\/v2\/posts\/350\/revisions\/534"}],"wp:attachment":[{"href":"http:\/\/tech.sosthe.sk\/index.php\/wp-json\/wp\/v2\/media?parent=350"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/tech.sosthe.sk\/index.php\/wp-json\/wp\/v2\/categories?post=350"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/tech.sosthe.sk\/index.php\/wp-json\/wp\/v2\/tags?post=350"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}