I-metric ephezulu ye-OSPF: ukunqanda ukudlula kwegatsha ngaphandle kokulisusa

Amahhovisi amabili axhunywe ngokusebenzisa igatsha okufanele lithwale ithrafikhi yalo futhi okuncane kakhulu okunye. Igatsha lidinga imizila eya kuzo zombili iziza, futhi asikho isiza okufanele sikhethe igatsha njengendlela ephakathi kwazo. Ukususa igatsha ku-topology kungaxazulula inkinga yokudlula futhi kwephule isidingo, ngoba igatsha lisadinga ukufinyelela kuzo zombili iziza, futhi zombili iziza zisadinga ukufinyelela egatsheni.

Okufunayo ukuthandwa, okuvezwe kuphrothokholi yokuhlela imizila, okushiya igatsha lifinyeleleka ngokuphelele futhi okwenza libe ukukhetha okubi kukho konke okudlula kulo. Hamba inkinga ngokulandelana ama-router akubona ngakho.

Qala ngendlela ofuna ukuyigwema

Dweba i-topology njengoba iphrothokholi iyibona, hhayi njengoba umdwebo uyibona. Yiziphi izixhumanisi ezakha ubumelwane, eziphi ezisesifundeni esisodwa, futhi eziphi kulezo zixhumanisi ezingathwala ithrafikhi phakathi kwamahhovisi amabili uma igatsha likhethwa? Lezi yimibuzo emithathu ehlukene, futhi umdwebo awuphenduli nowodwa wazo ngokuthembeka.

Bese uthola enye indlela. Uma indlela eyodwa phakathi kwamahhovisi idlula egatsheni, awekho umetric ongahambisa ithrafikhi kulo, ngoba ithrafikhi ayinandawo yokuya. Ukweqile akuyona imininingwane yalo mklamo; kuyisibopho sokuqala. Indlela yesibili ekhona kuphela ephepheni ayibalwa.

show ip ospf neighbor
show ip ospf interface brief
show ip route 10.40.0.0

Le mibono emithathu iphendula imibuzo ehlukene: ubani umakhelwane, yiziphi izixhumanisi ezihlanganyelayo nangezindleko ezingakanani, futhi iyiphi indlela idivayisi eyikhethayo manje. Ukusetshenziswa kwe-tunnel kwengeza eyesine: umugqa emdwesho awusona ubufakazi bokuthi ubumelwane bakheka ngawo, futhi ubumelwane obukhethiwe awusona ubufakazi bokuthi ukudlulisela kulandela indlela efanayo. Kuzo izakhiwo ze-tunnel yilapho le gesi ibonakala khona kakhulu.

I-metric ephezulu imemezela ini

I-RFC 6987 ichaza i-router ememezela izixhumanisi zayo ezingezona stub nge-metric ephezulu yesixhumanisi, echazwe njenge-0xffff. I-router isachaza yona kanye nezixhumanisi zayo; imane nje izikala phezulu kobubanzi, ngakho yonke enye i-router ibala indlela edlula kuyo njengento ebizayo.

Lokhu ukushintsha kwe-router-LSA, hhayi ukususa i-topology. Umehluko ubalulekile: ukusula i-router-LSA kuhoxisa ulwazi lwe-topology ngokwalo, okungase futhi kuhoxise ubudlelwano obudingekayo ukufinyelela i-router kanye neziqalo ezingemuva kwayo. Ukugcina isimemezelo nokukhulisa intengo yaso kugcina lobo budlelwano. Lowo ngumehluko wonke phakathi kwale ndlela nokususa.

Indlela RFC 6987 futhi ayihlobene nezinhlobo zezifunda noma nokukhethwa kwe-router eqokiwe. Isifunda se-stub sivimbela isigaba semimemezelo yesimo sesixhumanisi emngceleni wesifunda, futhi i-router ye-stub ikala izixhumanisi zayo. Amagama afanayo, umshini ongahlobene.

Kungani ukufinyeleleka kuhlala kukhona, ukudlula kungabi khona

Amanye ama-router asenawo umzila oya eziqalweni ezixhunywe egatsheni, ngoba igatsha lisazimemezela futhi izixhumanisi zisakhona. Okushintshayo yizindleko eziphelele zanoma iyiphi indlela edlula egatsheni isiya kwenye indawo. Iziqalo azihambi; intengo yokuwela i-router iyona kuphela eshintshayo.

Kuthrafikhi okungumthombo wayo noma okuyiwa kuyo igatsha ngokwalo, isixhumanisi esibizayo sisendleleni eyodwa enengqondo, ngakho siyasetshenziswa. Kuthrafikhi phakathi kwamahhovisi amabili, enye indlela manje iyawina ngezindleko, futhi igatsha liphuma esinqumweni sokudlulisela ngaphandle kokunyamalala ku-topology. Izinhlangothi ezimbili, izimpendulo ezimbili ezihlukene, futhi zombili ziyindlela esebenzayo.

Lokho kungukuziphatha okufanele kuqinisekiswe hhayi ukucatshangwa. Bheka i-router-LSA ekhiqizwa igatsha, bese ubheka indlela ekhethwa enye i-router eya endaweni engemuva kwegatsha naseyeni endaweni kwelinye ihhovisi. Izimpendulo zombili kufanele zehluke, futhi uma zingahlukani, ushintsho lwe-metric alufinyeleli esinqumweni ocabanga ngaso.

Inkinga yendlela yokugcina

I-RFC efanayo icacile ukuthi le ndlela ayivimbeli ukusetshenziswa. Uma enye indlela ihluleka, ama-router abuyela endleleni ebizayo edlula egatsheni, ngoba iseyindlela evumelekile futhi iphrothokholi ikhetha umzila obizayo kunokungabi nawo umzila.

Ukuthi lokho kubuyela kuyamukeleka yini kuwumbuzo wenqubomgomo okufanele uwuphendule ngaphambi kokusetshenziswa. Igatsha elisekuxhumaneni okuncane phezulu elithwala ithrafikhi phakathi kwamahhovisi ngokuzumayo lingaba kubi kunokuphazamiseka, futhi lingaba yilokho okuyikho ngqo okukufunayo ngesikhathi sokulungisa. Zombili izimpendulo zivumelekile; ukuthula akusona.

Uma isidingo siwukuvimbela okuqinile hhayi ukuthandwa, umklamo we-metric wodwa ngeke ukukhiqize. Udinga ukuphoqelelwa kokudlulisela okuhambisana nenhloso, kanye nokuziphatha okuchaziwe kwalelo cala lapho ithrafikhi ifika noma kunjalo. Ukumemezela indlela njengento esebenzisekayo bese ulahla ithrafikhi kwakha umgodi omnyama okunzima ukuwuhlonza kunomjikelezo womzila.

Nge-OSPFv3, i-RFC ixoxa nge-bit R njengenye indlela yokukhipha ukuhlanganyela ekudluleni. Ungacabangi ukuthi izuza ukuziphatha okufanayo kwendlela yokugcina njengendlela ye-metric ephezulu, futhi ungakopishi izilungiselelo phakathi kwemindeni emibili yamakheli njengokungathi kuyisici esisodwa.

Kufakazela ngaphansi kwezimo ezijwayelekile nezehlulekayo

Hlola kabili: kanye lapho zombili izindlela zikhona futhi kanye lapho indlela ekhethiwe isusiwe. Ukuhlola kokuqala kukhombisa ukuthi ukuthandwa kuyasebenza, futhi okwesibili kukhombisa ukuthi inethiwekhi yenzani lapho ukuthandwa kungahlonishwa. Ukweqa ukuhlola kwesibili kushiya ingxenye ebalulekile ingahloliwe.

show ip ospf database router 10.0.0.3
show ip route 172.20.8.0
traceroute 172.20.8.1

Umbono wengqoqo ledatha ukhombisa i-metric emenyezelwe, ukusesha umzila kukhombisa isinyathelo esilandelayo esikhethiwe, futhi ukulandelela kukhombisa ukuthi amaphakethe aya ngempela kuphi. Uma lezi zintathu zivumelana, unomklamo oqinisekisiwe hhayi ukulungiselelwa okubonakala kulungile.

Bese ubuyisela indlela ekhethiwe futhi uqinisekise ukuthi igatsha libuyela ekuthwaleni ithrafikhi yalo kuphela. Isinyathelo sokubuyisela singesokuhlola hhayi sokuhlanza, ngoba umklamo osebenza kuze kube ushintsho olulandelayo awuwona umklamo. Bhala imiphumela yomibili, kuhlanganise nokubuyela, ngoba eyesibili iyimpendulo izothi umuntu ayidinge ngehora lesithathu ebusuku.