Shin VPNv4 na buƙatar MPLS a cikin cibiya? Ba lallai ba
BGP VPNv4 yana tattauna mahallin rarraba hanyoyi, ba hanyar turawa ba. Ka raba shigo da, warware mataki na gaba da kuma lulluɓe da za ka iya amfani da shi.
Kunna rukunin adireshin VPNv4 tsakanin na'urori biyu yana ƙirƙirar mahallin rarraba hanyoyi kawai, ba wani abu ba. Ba ya girka hanyar turawa, kuma ba ya faɗin wace lulluɓe za ta ɗauki fakitin abokin ciniki zuwa ƙarshen nesa. Da zarar an raba waɗannan gaskiyoyi biyu, tambayar «shin wannan na buƙatar MPLS a cikin cibiya» ta zama ƙarami kuma mai yiwuwa a amsa game da matakin bayanai da dandali ke tallafawa.
Abin da rukunin adireshin ke tattaunawa da gaske
BGP mai ka'idoji da yawa yana ɗaukar bayanin isar da layin cibiyar sadarwa na VPNv4 ƙarƙashin AFI 1 da SAFI 128, kuma kowane shigarwa yana haɗa mai bambanta hanya da prefix da kuma tambari. Zaman yana tattauna cewa duka masu magana za su iya ɓoye da buɗe wannan bayanin. Abin da ba ya tattaunawa shi ne matakin bayanai. Duk abin da ke bayan wannan sakin layi ya shafi turawa ne, kuma babu ɗaya daga cikinsu da zaman ya warware shi ta hanyar tashi.
Don haka zaman da ya yi nasara shaida ce ta iyawar matakin sarrafawa, ba ta turawa ba. Na'ura na iya riƙe dubban shigarwar VPNv4 kuma har yanzu ta jefar da kowane fakitin abokin ciniki, wanda shine dalilin da ya sa ake rikita nau'ikan gazawa biyu tun farko.
Lura da tambarin da ke cikin NLRI. Tambarin sabis ne, an ɗaure shi da prefix a cikin VRF, kuma yana da rawar turawa da zarar fakitin ya isa ƙarshen fitarwa. Ko wata na'urar wucewa tana karanta shi, yanke shawara ce ta ƙira daban.
Karɓa, shigo da kaya da turawa matakai uku ne
Karɓar hanya, samun izinin amfani da ita, da iya turawa da ita sassa daban-daban na na'urar ke yi. BGP yana adana abin da yake ji; manufar shigo da kaya da daidaiton manufar hanya sun yanke shawarar wace VRF za ta iya la'akari da ita; sannan matakin turawa dole ya warware mataki na gaba da aka sanar zuwa wani abu da zai iya tura shi a waya da gaske.
| Step in the chain | What has to be true | How it fails quietly |
|---|---|---|
| NLRI exchange | Both speakers negotiate the VPNv4 capability | Session stays up while the family is never activated |
| Import eligibility | A route target on the received route matches the VRF import policy | The route exists in the table but never enters the VRF |
| Next-hop resolution | The advertised next hop resolves to a usable tunnel or label path | Best path is selected, then marked unreachable or unusable |
| Encapsulation | The egress endpoint can decapsulate what the ingress produced | Packets arrive and are discarded for a format mismatch |
A cikin wannan mataki na tsakiya ne mafi yawan gazawa masu ban mamaki suke. Hanya na iya kasancewa a cikin teburin BGP, ingantacciya kuma har ma mafi kyau, yayin da teburin hanyoyin VRF ya kasance fanko saboda babu manufar hanya da ta dace da jerin shigo da kaya. Babu abin da ke rubuta kuskuren ka'ida, saboda babu kuskuren ka'ida da ya faru.
Mataki na ƙarshe shine inda tallafin dandali ke bayyana. Mataki na gaba da ake iya samu a cikin ƙasan ƙasa ba ya warwarewa kai tsaye a matsayin jigilar sabis na VPN, kuma na'urar na iya buƙatar takamaiman nau'in rami, takamaiman aikin tambari, ko duka biyu. Karanta matsayin warwarewa ya fi ba da labari fiye da karanta adadin hanyoyi.
Cibiyar IP na iya ɗaukar tari wanda ba ta taɓa musanya shi ba
Bambancin da ya cancanci riƙewa shine tsakanin «cibiyar ba ta gudanar da MPLS» da «babu tambari a ko'ina cikin sabis». Waɗannan da'awa ne daban-daban, kuma na farko ne kawai bayani game da na'urorin wucewa. RFC 4023 ya bayyana ɗaukar MPLS ta ramukan IP ko GRE, kuma wannan shine hanyar da ke sa da'awa ta biyu ta yiwu a kan cibiyar IP kawai.
customer packet + service label
encapsulated in GRE, addressed to the egress tunnel endpoint
forwarded by ordinary IP routers on the outer header
decapsulated at the endpoint, label still meaningfulNa'urorin wucewa suna turawa bisa ga makomar IP ta waje kuma ba sa buƙatar prefix na abokin ciniki ko musanya tambari na asali. A ƙarshen nesa ana cire ramin waje kuma tambarin sabis ya ci gaba da aikinsa. Cibiyar ta motsa kaya marar bayyana, wanda shine ainihin abin da cibiyar sadarwar IP ta fi kyau a ciki.
Abin da wannan ƙira ba ta ba ka shine tabbacin duniya. Ba hujja ba ce cewa kowane na'ura yana warware kowane mataki na gaba na VPNv4 a kan kowace fuska ta GRE, kuma ba dalili ba ne don share ingantaccen tsarin MPLS na asali. Misali ne na gaba da da'awar duniya, kuma tambayar aiki ta kasance cikin gida ga dandali. Rubuta wannan tambayar a matsayin iyakacin dandali maimakon ka'idar yarjejeniya.
Yi tafiya da sarkar a kan akwatin har sai ta karye
Fara daga hanyar da aka karɓa kuma tsaya a mataki na farko da ya kasa, domin ba za a iya bincikar matakai na gaba ba yayin da na baya ya karye. Umarni huɗu sun rufe mafi yawansu a cikin aiwatarwa na yau da kullum.
show bgp vpnv4 unicast all summary
show bgp vrf CUSTOMER_A ip route 198.51.100.0/24
show ip route vrf CUSTOMER_A 198.51.100.0
show mpls forwarding-table vrf CUSTOMER_AKaranta su a matsayin jeri ba a matsayin bincike huɗu masu zaman kansu ba. Na farko ya tabbatar da cewa rukunin yana aiki kuma abokin yana musayar hanyoyi; na biyu yana nuna ko prefix ya zo da mataki na gaba mai amfani; na uku ya tabbatar da cancantar shigo da kaya; na huɗu yana nuna ko matakin turawa ya ɗaure tambari ko rami da shi.
Sannan gwada hanyar aikin a duka kwatance biyu, da MTU wanda ke jure lulluɓe. GRE yana ƙara baytocin kan layi, kuma hanyar da ta wuce ƙananan gwaje-gwaje na iya kasawa a fakitin cikakken girma a hanya ɗaya kawai, wanda ke kama da laifin aikace-aikace maimakon jigila.
Bayanan aiki biyu sun rufe zagayowar. GRE lulluɓe ne, ba sirri ba, don haka cibiyar sadarwar wucewa da ba a amince da ita tana buƙatar ingantaccen tsarin tsaro a sama maimakon zato. Kuma rubuta wace lulluɓe dandali ke tallafawa da gaske kafin bitar ƙira, domin wannan amsa ɗaya ce ke yanke shawarar ko cibiyar IP kawai zaɓi ne ingantacce ko shiri da ba zai iya turawa ba.