{"id":37988,"date":"2019-10-31T22:21:01","date_gmt":"2019-10-31T19:21:01","guid":{"rendered":"https:\/\/prohoster.info\/blog\/trening-cisco-200-125-ccna-v3-0-den-37-stp-vybor-root-bridge-funktsii-portfast-i-bpdu-guard-chast-2\/"},"modified":"2019-10-31T22:21:01","modified_gmt":"2019-10-31T19:21:01","slug":"trening-cisco-200-125-ccna-v3-0-den-37-stp-vybor-root-bridge-funktsii-portfast-i-bpdu-guard-chast-2","status":"publish","type":"post","link":"https:\/\/prohoster.info\/cs\/blog\/administrirovanie\/trening-cisco-200-125-ccna-v3-0-den-37-stp-vybor-root-bridge-funktsii-portfast-i-bpdu-guard-chast-2","title":{"rendered":"Tr\u00e9nink Cisco 200-125 CCNA v3.0. Den 37. STP: v\u00fdb\u011br Root Bridge, funkce PortFast a BPDU guard. \u010c\u00e1st 2","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

P\u0159edpokl\u00e1dejme, \u017ee STP je ve stavu konvergence. Co se stane, kdy\u017e vezmu kabel a p\u0159\u00edmo p\u0159ipoj\u00edm switch N k root switchi A? Root Bridge \u00abuvid\u00ed\u00bb, \u017ee se mu objevil nov\u00fd aktivovan\u00fd port, a vy\u0161le p\u0159es n\u011bj BPDU. <\/p>\n

\"Tr\u00e9nink
\n
\nSwitch N, p\u0159ij\u00edmaj\u00edc\u00ed tento r\u00e1mec s nulovou hodnotou, ur\u010d\u00ed cenu trasy p\u0159es nov\u00fd port jako 0+19 = 19, p\u0159i\u010dem\u017e cena jeho root portu je 76. Pot\u00e9 port switche N, kter\u00fd byl d\u0159\u00edve v disabled stavu, projde v\u0161emi f\u00e1zemi p\u0159echodu a p\u0159epne se do re\u017eimu p\u0159enosu za 50 sekund. Pokud jsou k tomuto switche p\u0159ipojena dal\u0161\u00ed za\u0159\u00edzen\u00ed, v\u0161echna ztrat\u00ed spojen\u00ed s root switchem a s\u00edt\u011bmi celkov\u011b na 50 sekund. <\/a><\/noindex><\/p>\n

Analogicky postupuje switch G, kter\u00fd od switche N obdr\u017e\u00ed r\u00e1mec BPDU s upozorn\u011bn\u00edm na cenu 19. Zm\u011bn\u00ed cenu sv\u00e9ho ur\u010den\u00e9ho portu na 19+19= 38 a p\u0159evezme ho jako nov\u00fd root port, proto\u017ee cena jeho p\u0159edchoz\u00edho Root Port je 57, co\u017e je v\u00edce ne\u017e 38. P\u0159itom za\u010dnou znovu v\u0161echny f\u00e1ze p\u0159id\u011blov\u00e1n\u00ed port\u016f trvaj\u00edc\u00ed 50 sekund, a nakonec se cel\u00e1 s\u00ed\u0165 zhrout\u00ed. <\/p>\n

\"Tr\u00e9nink
\n
\nNyn\u00ed se pod\u00edvejme, co se stane v podobn\u00e9 situaci p\u0159i pou\u017eit\u00ed RSTP. Root switch p\u0159esn\u011b takt\u00e9\u017e vy\u0161le BPDU p\u0159ipojen\u00e9mu switchi N, ale ihned pot\u00e9 zablokuje sv\u016fj port. Po obdr\u017een\u00ed tohoto r\u00e1mce switch N ur\u010d\u00ed, \u017ee tato trasa m\u00e1 ni\u017e\u0161\u00ed cenu ne\u017e jeho root port, a okam\u017eit\u011b sv\u016fj port zablokuje. Pot\u00e9 N za\u0161le root switchi Proposal s \u017e\u00e1dost\u00ed o otev\u0159en\u00ed nov\u00e9ho portu, proto\u017ee jeho cena je ni\u017e\u0161\u00ed ne\u017e cena ji\u017e existuj\u00edc\u00edho root portu. Jakmile root switch souhlas\u00ed s \u017e\u00e1dost\u00ed, odblokuje sv\u016fj port a po\u0161le Agreement switchi N, po \u010dem\u017e N u\u010din\u00ed nov\u00fd port sv\u00fdm root portem. <\/p>\n

\"Tr\u00e9nink
\n
\nD\u00edky mechanismu Proposal\/Agreement se tak p\u0159e\u0159azen\u00ed root portu uskute\u010dn\u00ed prakticky okam\u017eit\u011b a v\u0161echna za\u0159\u00edzen\u00ed p\u0159ipojen\u00e1 k switchi N neztrat\u00ed spojen\u00ed se s\u00edt\u00ed.
\nP\u0159id\u011blen\u00edm nov\u00e9ho Root Portu p\u0159em\u011bn\u00ed switch N star\u00fd root port na alternativn\u00ed port. Tot\u00e9\u017e se stane se switchem G \u2013 vym\u011bn\u00ed si se switchi N zpr\u00e1vy Proposal\/Agreement, p\u0159id\u011bl\u00ed nov\u00fd root port a zablokuje ostatn\u00ed porty. Pot\u00e9 proces pokra\u010duje v dal\u0161\u00edm segmentu s\u00edt\u011b se switchem F. <\/p>\n

\"Tr\u00e9nink
\n
\nSwitch F, po anal\u00fdze n\u00e1klad\u016f, zjist\u00ed, \u017ee cesta k hlavn\u00edmu switchi p\u0159es doln\u00ed port bude st\u00e1t 57, p\u0159i\u010dem\u017e ji\u017e existuj\u00edc\u00ed cesta p\u0159es horn\u00ed port stoj\u00ed 38, a v\u0161echno nech\u00e1, jak to je. Kdy\u017e se o tom dozv\u00ed, switch G zablokuje port sm\u011brem k F a bude p\u0159esm\u011brov\u00e1vat provoz na hlavn\u00ed switch novou cestou G-H-A. <\/p>\n

Dokud switch F neobdr\u017e\u00ed n\u00e1vrh\/dohodu od switche G, bude m\u00edt sv\u016fj doln\u00ed port zablokovan\u00fd, aby zabr\u00e1nil tvorb\u011b smy\u010dek. Tak\u017ee vid\u00edte, \u017ee RSTP je velmi rychl\u00fd protokol, kter\u00fd nevytv\u00e1\u0159\u00ed v s\u00edti probl\u00e9my typick\u00e9 pro STP.
\nNyn\u00ed p\u0159ejd\u011bme k p\u0159\u00edkaz\u016fm. Mus\u00edte se dostat do glob\u00e1ln\u00edho konfigura\u010dn\u00edho re\u017eimu switche a vybrat re\u017eim PVST nebo RPVST pomoc\u00ed p\u0159\u00edkazu spanning-tree mode . Pot\u00e9 mus\u00edte rozhodnout, jak zm\u011bnit prioritu konkr\u00e9tn\u00ed VLAN. K tomu se pou\u017e\u00edv\u00e1 p\u0159\u00edkaz spanning-tree vlan priority . Z posledn\u00edho videoz\u00e1znamu byste si m\u011bli pamatovat, \u017ee priorita je \u010d\u00edslo d\u011bliteln\u00e9 4096 a v\u00fdchoz\u00ed hodnota je 32768 plus \u010d\u00edslo VLAN. Pokud jste vybrali VLAN1, tak v\u00fdchoz\u00ed priorita bude 32768+1= 32769. <\/p>\n

\"Tr\u00e9nink
\n
\nK \u010demu m\u016f\u017ee b\u00fdt pot\u0159eba m\u011bnit prioritu s\u00edt\u00ed? V\u00edme, \u017ee BID se skl\u00e1d\u00e1 z \u010d\u00edseln\u00e9 hodnoty priority a MAC adresy. MAC adresa za\u0159\u00edzen\u00ed se ned\u00e1 zm\u011bnit, m\u00e1 trvalou hodnotu, tak\u017ee lze zm\u011bnit pouze velikost priority.<\/p>\n

P\u0159edstavme si, \u017ee existuje velk\u00e1 s\u00ed\u0165, kde jsou v\u0161echna za\u0159\u00edzen\u00ed Cisco propojena v kruhov\u00e9 topologii. V tomto p\u0159\u00edpad\u011b je v\u00fdchoz\u00ed hodnotou aktivov\u00e1n PVST, tak\u017ee syst\u00e9m vybere hlavn\u00ed switch. Pokud maj\u00ed v\u0161echna za\u0159\u00edzen\u00ed stejnou prioritu, p\u0159ednost dostane switch se nejstar\u0161\u00ed MAC adresou. To v\u0161ak m\u016f\u017ee b\u00fdt 10-12 let star\u00fd switch zastaral\u00e9ho typu, kter\u00fd nem\u00e1 dostatek v\u00fdkonu a kapacity 'vedouc\u00ed' tak rozs\u00e1hlou s\u00ed\u0165.
\nZ\u00e1rove\u0148 m\u016f\u017ee b\u00fdt ve va\u0161\u00ed s\u00edti nejnov\u011bj\u0161\u00ed switch za n\u011bkolik tis\u00edc dolar\u016f, kter\u00fd mus\u00ed 'podl\u00e9hat' star\u00e9mu switchi, jeho\u017e MAC adresa je ni\u017e\u0161\u00ed. Pokud se star\u00fd switch stane hlavn\u00edm switchem, sv\u011bd\u010d\u00ed to o v\u00e1\u017en\u00e9 chyb\u011b v n\u00e1vrhu s\u00edt\u011b.<\/p>\n

Proto mus\u00edte p\u0159ej\u00edt do nastaven\u00ed nov\u00e9ho switche a p\u0159i\u0159adit mu minim\u00e1ln\u00ed hodnotu priority, nap\u0159\u00edklad 0. P\u0159i pou\u017eit\u00ed VLAN1 bude celkov\u00e1 hodnota priority rovna 0+1=1 a v\u0161echna ostatn\u00ed za\u0159\u00edzen\u00ed ho budou neust\u00e1le pova\u017eovat za ko\u0159enov\u00fd switch.<\/p>\n

Te\u010f si p\u0159edstavte takovou situaci. Pokud se ko\u0159enov\u00fd switch z n\u011bjak\u00e9ho d\u016fvodu stane nedostupn\u00fdm, m\u016f\u017eete cht\u00edt, aby nov\u00fdm ko\u0159enov\u00fdm switchem nebyl jen jak\u00fdkoli switch s ni\u017e\u0161\u00ed prioritou, ale konkr\u00e9tn\u00ed switch s lep\u0161\u00edmi s\u00ed\u0165ov\u00fdmi funkcemi. V takov\u00e9m p\u0159\u00edpad\u011b se v nastaven\u00ed Root Bridge pou\u017e\u00edv\u00e1 p\u0159\u00edkaz, kter\u00fd ur\u010duje prim\u00e1rn\u00ed a sekund\u00e1rn\u00ed ko\u0159enov\u00e9 switche: spanning-tree vlan root . Hodnota priority pro prim\u00e1rn\u00ed switch Primary bude 32768 \u2013 4096 \u2013 4096 = 24576. Pro sekund\u00e1rn\u00ed switch Secondary se vypo\u010d\u00edt\u00e1 podle vzorce 32768 \u2013 4096 = 28672.<\/p>\n

Nemus\u00edte tyto \u010d\u00edsla zad\u00e1vat ru\u010dn\u011b \u2013 syst\u00e9m to ud\u011bl\u00e1 za v\u00e1s automaticky. Tak\u017ee ko\u0159enov\u00fdm switchem bude switch s prioritou 24576 a v p\u0159\u00edpad\u011b jeho nedostupnosti switch s prioritou 28672, p\u0159i\u010dem\u017e priorita v\u0161ech ostatn\u00edch switch\u016f je standardn\u011b minim\u00e1ln\u011b 32768. Takto byste m\u011bli postupovat, pokud nechcete, aby syst\u00e9m automaticky ur\u010dil ko\u0159enov\u00fd switch. <\/p>\n

Pokud chcete prohl\u00e9dnout nastaven\u00ed protokolu STP, mus\u00edte pou\u017e\u00edt p\u0159\u00edkaz show spanning-tree summary. Nyn\u00ed si prozkoumejme v\u0161echny dnes prob\u00edran\u00e9 t\u00e9ma pomoc\u00ed Packet Tracer. Pou\u017e\u00edv\u00e1m topologii s\u00edt\u011b se 4 switchemi modelu 2690, co\u017e nen\u00ed d\u016fle\u017eit\u00e9, proto\u017ee v\u0161echny modely switch\u016f Cisco podporuj\u00ed STP. Jsou navz\u00e1jem propojeny tak, aby s\u00ed\u0165 tvo\u0159ila uzav\u0159en\u00fd kruh. <\/p>\n

Ve v\u00fdchoz\u00edm nastaven\u00ed za\u0159\u00edzen\u00ed Cisco pracuj\u00ed v re\u017eimu PSTV+, co\u017e znamen\u00e1, \u017ee pro konvergenci ka\u017ed\u00e9mu portu bude pot\u0159eba maxim\u00e1ln\u011b 20 sekund. Panel simulace umo\u017e\u0148uje zobrazen\u00ed odes\u00edl\u00e1n\u00ed provozu a p\u0159ehled parametr\u016f vytvo\u0159en\u00e9 s\u00edt\u011b.<\/p>\n

\"Tr\u00e9nink
\n
\nVid\u00edte, co p\u0159edstavuje r\u00e1mec STP BPDU. Pokud vid\u00edte ozna\u010den\u00ed verze 0, znamen\u00e1 to, \u017ee m\u00e1te p\u0159ed sebou STP, proto\u017ee pro RSTP se pou\u017e\u00edv\u00e1 verze 2. Zde je tak\u00e9 uvedena hodnota Root ID, kter\u00e1 se skl\u00e1d\u00e1 z priority a MAC adresy ko\u0159enov\u00e9ho switche, a odpov\u00eddaj\u00edc\u00ed hodnota Bridge ID. <\/p>\n

\"Tr\u00e9nink
\n
\nTyto hodnoty jsou si rovny, proto\u017ee cena trasy k ko\u0159enov\u00e9mu p\u0159ep\u00edna\u010di pro SW0 je 0, tak\u017ee je s\u00e1m ko\u0159enov\u00fdm p\u0159ep\u00edna\u010dem. Po zapnut\u00ed p\u0159ep\u00edna\u010d\u016f do\u0161lo k automatick\u00e9mu v\u00fdb\u011bru Root Bridge d\u00edky pou\u017eit\u00ed STP a s\u00ed\u0165 za\u010dala fungovat. Vid\u00edte, \u017ee k prevenci smy\u010dky byl horn\u00ed port Fa0\/2 p\u0159ep\u00edna\u010de SW2 p\u0159eveden do stavu Blocking, co\u017e nazna\u010duje oran\u017eov\u00e1 barva indik\u00e1toru. <\/p>\n

\"Tr\u00e9nink
\n
\nP\u0159ejdeme na konzoli nastaven\u00ed p\u0159ep\u00edna\u010de SW0 a pou\u017eijeme p\u00e1r p\u0159\u00edkaz\u016f. Prvn\u00ed je p\u0159\u00edkaz show spanning-tree, po jeho\u017e zad\u00e1n\u00ed se na obrazovce zobraz\u00ed informace o re\u017eimu PSTV+ pro s\u00ed\u0165 VLAN1. Pokud pou\u017eijeme v\u00edce VLAN, v doln\u00ed \u010d\u00e1sti okna se objev\u00ed dal\u0161\u00ed blok informac\u00ed pro druhou a dal\u0161\u00ed pou\u017e\u00edvan\u00e9 s\u00edt\u011b. <\/p>\n

\"Tr\u00e9nink
\n
\nVid\u00edte, \u017ee protokol STP je dostupn\u00fd podle standardu IEEE, co\u017e znamen\u00e1 pou\u017eit\u00ed PVSTP+. Technicky se nejedn\u00e1 o standard .1d. D\u00e1le jsou zde uvedeny informace Root ID: priorita 32769, MAC adresa ko\u0159enov\u00e9ho za\u0159\u00edzen\u00ed, cena 19 atd. N\u00e1sleduj\u00ed informace Bridge ID, kde je nahl\u00e9dnuto do hodnoty priority 32768 +1, a je uvedena dal\u0161\u00ed MAC adresa. Jak vid\u00edte, m\u00fdlil jsem se \u2014 p\u0159ep\u00edna\u010d SW0 nen\u00ed ko\u0159enov\u00fdm p\u0159ep\u00edna\u010dem, ko\u0159enov\u00fd p\u0159ep\u00edna\u010d m\u00e1 jinou MAC adresu uvedenou v parametrech Root ID. Mysl\u00edm, \u017ee to souvis\u00ed s t\u00edm, \u017ee SW0 obdr\u017eel r\u00e1mec BPDU s informac\u00ed, \u017ee n\u011bjak\u00fd p\u0159ep\u00edna\u010d v s\u00edti m\u00e1 v\u011bt\u0161\u00ed d\u016fvody hr\u00e1t roli ko\u0159enov\u00e9ho.<\/p>\n

(pozn\u00e1mka p\u0159ekladatele: Root ID \u2013 identifik\u00e1tor ko\u0159enov\u00e9ho p\u0159ep\u00edna\u010de, shodn\u00fd pro v\u0161echna za\u0159\u00edzen\u00ed stejn\u00e9 s\u00edt\u011b VLAN, pracuj\u00edc\u00ed podle protokolu STP, Bridge ID \u2013 identifik\u00e1tor m\u00edstn\u00edho p\u0159ep\u00edna\u010de v r\u00e1mci Root Bridge, kter\u00fd m\u016f\u017ee b\u00fdt r\u016fzn\u00fd pro r\u016fzn\u00e9 p\u0159ep\u00edna\u010de a r\u016fzn\u00e9 VLAN).<\/p>\n

Dal\u0161\u00edm aspektem, kter\u00fd nazna\u010duje, \u017ee SW0 nen\u00ed ko\u0159enov\u00fdm p\u0159ep\u00edna\u010dem, je to, \u017ee ko\u0159enov\u00fd p\u0159ep\u00edna\u010d nem\u00e1 Root Port, \u0430 v tomto p\u0159\u00edpad\u011b jsou p\u0159\u00edtomny jak Root Port, tak Designated Port, nach\u00e1zej\u00ed se ve stavu forwarding. Tak\u00e9 vid\u00edte typ p\u0159ipojen\u00ed p2p, neboli \u201epoint-to-point\u201c. To znamen\u00e1, \u017ee porty fa0\/1 a fa0\/2 jsou p\u0159\u00edmo p\u0159ipojeny k sousedn\u00edm p\u0159ep\u00edna\u010d\u016fm.
\nPokud by jak\u00fdkoli port byl p\u0159ipojen k hubu, typ spojen\u00ed by byl ozna\u010den jako shared, pozd\u011bji se na to pod\u00edv\u00e1me. Pokud zad\u00e1m p\u0159\u00edkaz pro zobrazen\u00ed shrnut\u00ed informac\u00ed show spanning-tree summary, uvid\u00edme, \u017ee tento switch je v re\u017eimu PVSTP, d\u00e1le n\u00e1sleduje v\u00fdpis nedostupn\u00fdch funkc\u00ed portu. <\/p>\n

\"Tr\u00e9nink
\n
\nD\u00e1le je uveden stav a po\u010det port\u016f, kter\u00e9 obsluhuj\u00ed VLAN1: blocking 0, listening 0, learning 0, ve stavu forwarding se nach\u00e1zej\u00ed 2 porty v re\u017eimu STP.
\nNe\u017e p\u0159ejdeme k switchi SW2, pod\u00edvejme se na nastaven\u00ed switchu SW1. K tomu pou\u017eijeme stejn\u00fd p\u0159\u00edkaz show spanning-tree.<\/p>\n

\"Tr\u00e9nink
\n
\nVid\u00edte, \u017ee MAC adresa Root ID ze switchu SW1 je stejn\u00e1 jako u SW0, proto\u017ee v\u0161echna za\u0159\u00edzen\u00ed v s\u00edti p\u0159i schod\u011b z\u00edsk\u00e1vaj\u00ed stejnou adresu za\u0159\u00edzen\u00ed Root Bridge, proto\u017ee d\u016fv\u011b\u0159uj\u00ed volb\u011b, kterou provedl protokol STP. Jak vid\u00edte, SW1 je ko\u0159enov\u00fdm switchem, proto\u017ee adresy Root ID a Bridge ID se shoduj\u00ed. Krom\u011b toho je zde zpr\u00e1va 'tento switch je ko\u0159enov\u00fd'. <\/p>\n

Dal\u0161\u00edm znakem ko\u0159enov\u00e9ho switche je to, \u017ee nem\u00e1 Root porty, oba porty jsou ozna\u010den\u00e9 jako Designated. Pokud jsou v\u0161echny porty zobrazeny jako Designated a nach\u00e1zej\u00ed se ve stavu forwarding, pak se jedn\u00e1 o ko\u0159enov\u00fd switch. <\/p>\n

Switch SW3 obsahuje podobn\u00e9 informace, a nyn\u00ed p\u0159ech\u00e1z\u00edm na SW2, proto\u017ee jeden z jeho port\u016f je ve stavu Blocking. Pou\u017e\u00edv\u00e1m p\u0159\u00edkaz show spanning-tree a vid\u00edme, \u017ee informace Root ID a hodnota priority jsou stejn\u00e9 jako u ostatn\u00edch switch\u016f.
\nD\u00e1le je uvedeno, \u017ee jeden z port\u016f je Alternative. Nenechte se t\u00edm zm\u00e1st, standard 802.1d to naz\u00fdv\u00e1 Blocking Port, a v PVSTP je zablokovan\u00fd port v\u017edy ozna\u010den jako Alternative. Tak\u017ee tento alternativn\u00ed port Fa0\/2 je ve zablokovan\u00e9m stavu, zat\u00edmco port Fa0\/1 funguje jako Root Port. <\/p>\n

Zablokovan\u00fd port se nach\u00e1z\u00ed v segmentu s\u00edt\u011b mezi switchem SW0 a switchem SW2, a d\u00edky tomu n\u00e1m nevznik\u00e1 smy\u010dka. Jak vid\u00edte, switche pou\u017e\u00edvaj\u00ed propojen\u00ed typu p2p, proto\u017ee k nim nejsou p\u0159ipojena \u017e\u00e1dn\u00e1 dal\u0161\u00ed za\u0159\u00edzen\u00ed. <\/p>\n

\"Tr\u00e9nink
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\nM\u00e1me s\u00ed\u0165, kter\u00e1 se sb\u00edh\u00e1 podle protokolu STP. Nyn\u00ed vezmu kabel a p\u0159\u00edmo p\u0159ipoj\u00edm switch SW2 k kone\u010dn\u00e9mu switchi SW1. Pot\u00e9 v\u0161echny porty SW2 za\u010dnou b\u00fdt ozna\u010dov\u00e1ny oran\u017eov\u00fdmi zna\u010dkami. <\/p>\n

\"Tr\u00e9nink
\n
\nPou\u017eit\u00edm p\u0159\u00edkazu show spanning-tree summary uvid\u00edme, \u017ee nejprve jsou dva porty ve stavu Listening, pot\u00e9 p\u0159ech\u00e1zej\u00ed do stavu Learning a po n\u011bkolika sekund\u00e1ch do stavu Forwarding, p\u0159i\u010dem\u017e barva ozna\u010den\u00ed se m\u011bn\u00ed na zelenou. Pokud nyn\u00ed zad\u00e1me p\u0159\u00edkaz show spanning-tree, je vid\u011bt, \u017ee Fa0\/1, kter\u00fd byl d\u0159\u00edve Root portem, nyn\u00ed p\u0159e\u0161el do stavu blokov\u00e1n\u00ed a stal se Alternate portem. <\/p>\n

\"Tr\u00e9nink
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\nPort Fa0\/3, ke kter\u00e9mu je p\u0159ipojen kabel ko\u0159enov\u00e9ho switche, se stal Root portem, a port Fa0\/2 se stal ur\u010den\u00fdm Designated portem. Poj\u010fme se znovu pod\u00edvat na prob\u00edhaj\u00edc\u00ed proces konvergence. Odpoj\u00edm kabel SW2-SW1 a vr\u00e1t\u00edm se k p\u0159edchoz\u00ed topologii. Vid\u00edte, \u017ee porty SW2 se nejprve blokuj\u00ed a op\u011bt se st\u00e1vaj\u00ed oran\u017eov\u00fdmi, pot\u00e9 p\u0159ech\u00e1zej\u00ed postupn\u011b p\u0159es stavy Listening a Learning a dostanou se do stavu Forwarding. P\u0159i\u010dem\u017e jeden port se st\u00e1v\u00e1 zelen\u00fdm, zat\u00edmco druh\u00fd, p\u0159ipojen\u00fd ke switchi SW0, z\u016fst\u00e1v\u00e1 oran\u017eov\u00fdm. Proces konvergence trval docela dlouho, to jsou n\u00e1klady na pr\u00e1ci STP.<\/p>\n

\"Tr\u00e9nink
\n
\nNyn\u00ed se pod\u00edvejme, jak funguje RSTP. Za\u010dneme se switchem SW2 a zad\u00e1me do jeho nastaven\u00ed p\u0159\u00edkaz spanning-tree mode rapid-pvst. Tento p\u0159\u00edkaz m\u00e1 pouze dv\u011b varianty parametr\u016f: pvst a rapid-pvst, pou\u017e\u00edv\u00e1m druh\u00fd. Po zad\u00e1n\u00ed p\u0159\u00edkazu switch p\u0159ech\u00e1z\u00ed do re\u017eimu RPVST, co\u017e lze ov\u011b\u0159it p\u0159\u00edkazem show spanning-tree. <\/p>\n

\"Tr\u00e9nink
\n
\nNa za\u010d\u00e1tku vid\u00edte zpr\u00e1vu, \u017ee nyn\u00ed m\u00e1me funk\u010dn\u00ed protokol RSTP. V\u0161echno ostatn\u00ed z\u016fstalo beze zm\u011bny. Pot\u00e9 mus\u00edm ud\u011blat tot\u00e9\u017e pro v\u0161echna ostatn\u00ed za\u0159\u00edzen\u00ed, a t\u00edm je nastaven\u00ed RSTP dokon\u010deno. Poj\u010fme se pod\u00edvat na fungov\u00e1n\u00ed tohoto protokolu, tak jak jsme to d\u011blali pro STP.<\/p>\n

Znovu p\u0159ipojuji kabelem switch SW2 p\u0159\u00edmo k ko\u0159enov\u00e9mu switchi SW1 - pod\u00edv\u00e1me se, jak rychle prob\u011bhne konvergence. Zad\u00e1v\u00e1m p\u0159\u00edkaz show spanning-tree summary a vid\u00edm, \u017ee dva porty switche jsou ve stavu Blocking, 1 ve stavu Forwarding. <\/p>\n

\"Tr\u00e9nink
\n
\nVid\u00edte, \u017ee konvergence prob\u011bhla prakticky okam\u017eit\u011b, tak\u017ee si m\u016f\u017eete ud\u011blat p\u0159edstavu o tom, jak rychle je RSTP ve srovn\u00e1n\u00ed se STP. D\u00e1le m\u016f\u017eeme pou\u017e\u00edt p\u0159\u00edkaz spanning-tree portfast default, kter\u00fd p\u0159evede v\u0161echny porty switche do re\u017eimu portfast ve v\u00fdchoz\u00edm nastaven\u00ed. To je relevantn\u00ed, pokud v\u011bt\u0161ina port\u016f switche jsou Edge porty, p\u0159\u00edmo p\u0159ipojen\u00e9 k hostitel\u016fm. Pokud m\u00e1me n\u011bjak\u00fd port, kter\u00fd nen\u00ed Edge, nastavujeme ho zp\u011bt do re\u017eimu spanning-tree. <\/p>\n

Pro nastaven\u00ed pr\u00e1ce s VLAN m\u016f\u017eete pou\u017e\u00edt p\u0159\u00edkaz spanning-tree vlan s parametry priority (nastav\u00ed prioritu switche pro spanning-tree) nebo root (ur\u010d\u00ed switch jako ko\u0159enov\u00fd). Pou\u017eijeme p\u0159\u00edkaz spanning-tree vlan 1 priority, p\u0159i\u010dem\u017e jako prioritu uvedeme libovoln\u00e9 \u010d\u00edslo, kter\u00e9 je n\u00e1sobkem 4096, v rozmez\u00ed od 0 do 61440. T\u00edmto zp\u016fsobem m\u016f\u017eeme ru\u010dn\u011b zm\u011bnit prioritu libovoln\u00e9 VLAN. <\/p>\n

M\u016f\u017eete zadat p\u0159\u00edkaz spanning-tree vlan 1 root s parametry primary nebo secondary, abyste nastavili hlavn\u00ed nebo z\u00e1lo\u017en\u00ed ko\u0159enov\u00fd port pro konkr\u00e9tn\u00ed s\u00ed\u0165. Pokud pou\u017eiji spanning-tree vlan 1 root primary, tento port bude hlavn\u00edm ko\u0159enov\u00fdm portem pro s\u00ed\u0165 VLAN1. <\/p>\n

Zad\u00e1m p\u0159\u00edkaz show spanning-tree a uvid\u00edme, \u017ee tento switch SW2 m\u00e1 prioritu 24577, MAC adresy Root ID a Bridge ID se shoduj\u00ed, co\u017e znamen\u00e1, \u017ee se nyn\u00ed stal ko\u0159enov\u00fdm switchem. <\/p>\n

\"Tr\u00e9nink
\n
\nVid\u00edte, jak rychle do\u0161lo k shod\u011b a zm\u011bn\u011b role switch\u016f. Nyn\u00ed zru\u0161\u00edm re\u017eim hlavn\u00edho switche p\u0159\u00edkazem no spanning-tree vlan 1 root primary, po \u010dem\u017e se jeho priorita vr\u00e1t\u00ed na p\u0159edchoz\u00ed hodnotu 32769 a role ko\u0159enov\u00e9ho switche se znovu p\u0159enese na SW1. <\/p>\n

Pod\u00edvejme se, jak funguje portfast. Zavedu p\u0159\u00edkaz int f0\/1, vstoup\u00edm do nastaven\u00ed tohoto portu a pou\u017eiji p\u0159\u00edkaz spanning-tree, po \u010dem\u017e syst\u00e9m poskytne n\u00e1vrhy hodnot parametr\u016f. <\/p>\n

\"Tr\u00e9nink
\n
\nD\u00e1le pou\u017eiji p\u0159\u00edkaz spanning-tree portfast, kter\u00fd lze zadat s parametry disable (deaktivuje funkci portfast pro tento port) nebo trunk (aktivuje funkci portfast pro tento port i v trunkov\u00e9m re\u017eimu). <\/p>\n

Pokud zad\u00e1te spanning-tree portfast, funkce se jednodu\u0161e aktivuje na tomto portu. Pro aktivaci funkce BPDU Guard je t\u0159eba pou\u017e\u00edt p\u0159\u00edkaz spanning-tree bpduguard enable, p\u0159\u00edkaz spanning-tree bpduguard disable tuto funkci deaktivuje. <\/p>\n

Rychle zm\u00edn\u00edm je\u0161t\u011b jednu v\u011bc. Pokud bude pro VLAN1 rozhran\u00ed switche SW2 ve sm\u011bru SW3 zablokov\u00e1no, p\u0159i jin\u00fdch nastaven\u00edch pro jinou VLAN, nap\u0159. VLAN2, m\u016f\u017ee se toto rozhran\u00ed st\u00e1t ko\u0159enov\u00fdm portem. Tento mechanismus umo\u017e\u0148uje vyva\u017eov\u00e1n\u00ed z\u00e1t\u011b\u017ee provozu \u2013 v jednom p\u0159\u00edpad\u011b je tento segment s\u00edt\u011b nevyu\u017e\u00edv\u00e1n, v jin\u00e9m \u2013 vyu\u017e\u00edv\u00e1n. <\/p>\n

Uk\u00e1\u017eu, co se stane, kdy\u017e p\u0159i p\u0159ipojen\u00ed hubu nastane sd\u00edlen\u00e9 rozhran\u00ed. P\u0159id\u00e1m hub do sch\u00e9matu a spoj\u00edm ho se switchem SW2 dv\u011bma kabely. <\/p>\n

\"Tr\u00e9nink
\n
\nP\u0159\u00edkaz show spanning-tree odraz\u00ed n\u00e1sleduj\u00edc\u00ed obraz. <\/p>\n

\"Tr\u00e9nink
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\nFa0\/5 (doln\u00ed lev\u00fd port switche) se st\u00e1v\u00e1 z\u00e1lo\u017en\u00edm portem, zat\u00edmco port Fa0\/4 (doln\u00ed prav\u00fd port switche) se st\u00e1v\u00e1 p\u0159id\u011blen\u00fdm designated-portem. Typ obou port\u016f je sd\u00edlen\u00fd, nebo shared. To znamen\u00e1, \u017ee segment rozhran\u00ed hub-switch je spole\u010dnou s\u00edt\u00ed. <\/p>\n

D\u00edky pou\u017eit\u00ed RSTP jsme z\u00edskali rozd\u011blen\u00ed na alternativn\u00ed a z\u00e1lo\u017en\u00ed porty. Pokud p\u0159epneme switch SW2 do re\u017eimu pvst p\u0159\u00edkazem spanning-tree mode pvst, uvid\u00edme, \u017ee rozhran\u00ed Fa0\/5 se op\u011bt p\u0159epne do stavu Alternative, proto\u017ee nyn\u00ed nen\u00ed rozd\u00edl mezi z\u00e1lo\u017en\u00edm portem a alternativn\u00edm portem. <\/p>\n

\"Tr\u00e9nink
\n
\nTo byla velmi dlouh\u00e1 lekce, a pokud jste n\u011bco nepochopili, doporu\u010duji ji znovu zhl\u00e9dnout. <\/p>\n

\r\n \"P\u0159ehr\u00e1t\r\n
<\/div>\r\n <\/div><\/center>
\nD\u011bkujeme, \u017ee s n\u00e1mi z\u016fst\u00e1v\u00e1te. L\u00edb\u00ed se v\u00e1m na\u0161e \u010dl\u00e1nky? Chcete vid\u011bt v\u00edce zaj\u00edmav\u00fdch materi\u00e1l\u016f? Podpo\u0159te n\u00e1s objedn\u00e1vkou nebo doporu\u010den\u00edm zn\u00e1m\u00fdm, 30 % sleva pro u\u017eivatele Habra na jedine\u010dn\u00fd analog entry-level server\u016f, kter\u00fd jsme pro v\u00e1s vymysleli:<\/b> Ve\u0161ker\u00e1 pravda o VPS (KVM) E5-2650 v4 (6 jader) 10GB DDR4 240GB SSD 1Gbps od 20 $ nebo jak spr\u00e1vn\u011b rozd\u011blit server?<\/a><\/noindex> (k dispozici varianty s RAID1 a RAID10, a\u017e 24 jader a a\u017e 40GB DDR4).<\/p>\n

Dell R730xd za polovinu ceny?<\/b> Jen u n\u00e1s 2 x Intel TetraDeca-Core Xeon 2x E5-2697v3 2.6GHz 14C 64GB DDR4 4x960GB SSD 1Gbps 100 TB od 199 $<\/a><\/noindex> v Nizozemsku! Dell R420 \u2014 2x E5-2430 2.2GHz 6C 128GB DDR3 2x960GB SSD 1Gbps 100TB \u2014 od 99 $!<\/b><\/b> \u010ct\u011bte o tom Jak postavit infrastrukturu podnikov\u00e9 t\u0159\u00eddy s pou\u017eit\u00edm server\u016f Dell R730xd E5-2650 v4 v hodnot\u011b 9000 eur za pakatel?<\/a><\/noindex>
\n
Zdroj: habr.com<\/a><\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

\u041f\u0440\u0435\u0434\u043f\u043e\u043b\u043e\u0436\u0438\u043c, \u0447\u0442\u043e STP \u043d\u0430\u0445\u043e\u0434\u0438\u0442\u0441\u044f \u0432 \u0441\u043e\u0441\u0442\u043e\u044f\u043d\u0438\u0438 \u0441\u0445\u043e\u0434\u0438\u043c\u043e\u0441\u0442\u0438. \u0427\u0442\u043e \u043f\u0440\u043e\u0438\u0437\u043e\u0439\u0434\u0435\u0442, \u0435\u0441\u043b\u0438 \u044f \u0432\u043e\u0437\u044c\u043c\u0443 \u043a\u0430\u0431\u0435\u043b\u044c \u0438 \u0441\u043e\u0435\u0434\u0438\u043d\u044e \u0441\u0432\u0438\u0442\u0447 \u041d \u043d\u0430\u043f\u0440\u044f\u043c\u0443\u044e \u0441 \u043a\u043e\u0440\u043d\u0435\u0432\u044b\u043c \u0441\u0432\u0438\u0442\u0447\u0435\u043c \u0410? Root Bridge \u00ab\u0443\u0432\u0438\u0434\u0438\u0442\u00bb, \u0447\u0442\u043e \u0443 \u043d\u0435\u0433\u043e \u043f\u043e\u044f\u0432\u0438\u043b\u0441\u044f \u043d\u043e\u0432\u044b\u0439 \u0437\u0430\u0434\u0435\u0439\u0441\u0442\u0432\u043e\u0432\u0430\u043d\u043d\u044b\u0439 \u043f\u043e\u0440\u0442, \u0438 \u043e\u0442\u043e\u0448\u043b\u0435\u0442 \u043f\u043e \u043d\u0435\u043c\u0443 BPDU. \u0421\u0432\u0438\u0442\u0447 \u041d, \u043f\u043e\u043b\u0443\u0447\u0438\u0432 \u044d\u0442\u043e\u0442 \u0444\u0440\u0435\u0439\u043c \u0441 \u043d\u0443\u043b\u0435\u0432\u043e\u0439 \u0441\u0442\u043e\u0438\u043c\u043e\u0441\u0442\u044c\u044e, \u043e\u043f\u0440\u0435\u0434\u0435\u043b\u0438\u0442 \u0441\u0442\u043e\u0438\u043c\u043e\u0441\u0442\u044c \u043c\u0430\u0440\u0448\u0440\u0443\u0442\u0430 \u0447\u0435\u0440\u0435\u0437 \u043d\u043e\u0432\u044b\u0439 \u043f\u043e\u0440\u0442 \u043a\u0430\u043a 0+19 =19 \u043f\u0440\u0438 […]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":28511,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[688],"tags":[],"class_list":["post-37988","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-administrirovanie"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\n","aioseo_head_json":{"title":"\ud83e\udd47\u0160kolen\u00ed Cisco 200-125 CCNA v3.0. 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Co se stane, kdy\u017e vezmu kabel a p\u0159\u00edmo spoj\u00edm switch N s ko\u0159enov\u00fdm switchem A?","canonical_url":"https:\/\/prohoster.info\/cs\/blog\/administrirovanie\/trening-cisco-200-125-ccna-v3-0-den-37-stp-vybor-root-bridge-funktsii-portfast-i-bpdu-guard-chast-2","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":null,"og:locale":"cs_CZ","og:site_name":"ProHoster | \u041a\u0443\u043f\u0438\u0442\u044c \u043d\u0430\u0434\u0435\u0436\u043d\u044b\u0439 \u0445\u043e\u0441\u0442\u0438\u043d\u0433 \u0434\u043b\u044f \u0441\u0430\u0439\u0442\u043e\u0432 \u0441 \u0437\u0430\u0449\u0438\u0442\u043e\u0439 \u043e\u0442 DDoS, VPS VDS \u0441\u0435\u0440\u0432\u0435\u0440\u044b","og:type":"article","og:title":"\ud83e\udd47\u0422\u0440\u0435\u043d\u0438\u043d\u0433 Cisco 200-125 CCNA v3.0. \u0414\u0435\u043d\u044c 37. STP: \u0432\u044b\u0431\u043e\u0440 Root Bridge, \u0444\u0443\u043d\u043a\u0446\u0438\u0438 PortFast \u0438 BPDU guard. \u0427\u0430\u0441\u0442\u044c 2 | ProHoster","og:description":"\u041f\u0440\u0435\u0434\u043f\u043e\u043b\u043e\u0436\u0438\u043c, \u0447\u0442\u043e STP \u043d\u0430\u0445\u043e\u0434\u0438\u0442\u0441\u044f \u0432 \u0441\u043e\u0441\u0442\u043e\u044f\u043d\u0438\u0438 \u0441\u0445\u043e\u0434\u0438\u043c\u043e\u0441\u0442\u0438. \u0427\u0442\u043e \u043f\u0440\u043e\u0438\u0437\u043e\u0439\u0434\u0435\u0442, \u0435\u0441\u043b\u0438 \u044f \u0432\u043e\u0437\u044c\u043c\u0443 \u043a\u0430\u0431\u0435\u043b\u044c \u0438 \u0441\u043e\u0435\u0434\u0438\u043d\u044e \u0441\u0432\u0438\u0442\u0447 \u041d \u043d\u0430\u043f\u0440\u044f\u043c\u0443\u044e \u0441 \u043a\u043e\u0440\u043d\u0435\u0432\u044b\u043c \u0441\u0432\u0438\u0442\u0447\u0435\u043c \u0410?","og:url":"https:\/\/prohoster.info\/cs\/blog\/administrirovanie\/trening-cisco-200-125-ccna-v3-0-den-37-stp-vybor-root-bridge-funktsii-portfast-i-bpdu-guard-chast-2","og:image":"https:\/\/prohoster.info\/wp-content\/uploads\/2021\/11\/logo-350.jpg","og:image:secure_url":"https:\/\/prohoster.info\/wp-content\/uploads\/2021\/11\/logo-350.jpg","og:image:width":350,"og:image:height":350,"article:published_time":"2019-10-31T19:21:01+00:00","article:modified_time":"2019-10-31T19:21:01+00:00","article:publisher":"https:\/\/www.facebook.com\/prohoster","article:author":"https:\/\/www.facebook.com\/prohoster"},"aioseo_meta_data":{"post_id":"37988","title":null,"description":null,"keywords":null,"keyphrases":null,"primary_term":null,"canonical_url":null,"og_title":null,"og_description":null,"og_object_type":"default","og_image_type":"default","og_image_url":null,"og_image_width":null,"og_image_height":null,"og_image_custom_url":null,"og_image_custom_fields":null,"og_video":null,"og_custom_url":null,"og_article_section":null,"og_article_tags":null,"twitter_use_og":false,"twitter_card":"default","twitter_image_type":"default","twitter_image_url":null,"twitter_image_custom_url":null,"twitter_image_custom_fields":null,"twitter_title":null,"twitter_description":null,"schema":{"blockGraphs":[],"customGraphs":[],"default":{"data":{"Article":[],"Course":[],"Dataset":[],"FAQPage":[],"Movie":[],"Person":[],"Product":[],"ProductReview":[],"Car":[],"Recipe":[],"Service":[],"SoftwareApplication":[],"WebPage":[]},"graphName":"","isEnabled":true},"graphs":[]},"schema_type":null,"schema_type_options":null,"pillar_content":false,"robots_default":true,"robots_noindex":false,"robots_noarchive":false,"robots_nosnippet":false,"robots_nofollow":false,"robots_noimageindex":false,"robots_noodp":false,"robots_notranslate":false,"robots_max_snippet":null,"robots_max_videopreview":null,"robots_max_imagepreview":"large","priority":null,"frequency":null,"local_seo":null,"seo_analyzer_scan_date":"2026-01-23 20:01:19","breadcrumb_settings":null,"limit_modified_date":false,"reviewed_by":null,"ai":null,"created":"2021-03-01 01:17:22","updated":"2026-01-23 20:01:19","focus_keyword":null,"additional_keywords":null,"truseo_locale":null},"gt_translate_keys":[{"key":"link","format":"url"}],"_links":{"self":[{"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/posts\/37988","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/comments?post=37988"}],"version-history":[{"count":0,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/posts\/37988\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/media\/28511"}],"wp:attachment":[{"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/media?parent=37988"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/categories?post=37988"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/tags?post=37988"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}