Yadda BGP ke aiki

Yau za mu kalli ka'idar BGP. Ba za mu yi magana na dogon lokaci game da dalilin da ya sa yake da kuma dalilin da yasa ake amfani da shi azaman yarjejeniya kawai ba. Akwai bayanai da yawa akan wannan batu, alal misali a nan.

To menene BGP? BGP ƙa'idar hanya ce mai ƙarfi kuma ita ce ka'idar EGP (Ƙofar Waje ta waje). Ana amfani da wannan ka'idar don gina hanyar sadarwa akan Intanet. Bari mu kalli yadda ake gina unguwa tsakanin manyan hanyoyin sadarwa na BGP guda biyu.

Yi la'akari da unguwa tsakanin Router1 da Router3. Bari mu saita su ta amfani da umarni masu zuwa:

router bgp 10
  network 192.168.12.0
  network 192.168.13.0
  neighbor 192.168.13.3 remote-as 10

router bgp 10
  network 192.168.13.0
  network 192.168.24.0
  neighbor 192.168.13.1 remote-as 10

Unguwa tsakanin tsarin mai cin gashin kansa guda ɗaya shine AS 10. Bayan shigar da bayanai akan na'ura mai ba da hanya tsakanin hanyoyin sadarwa, kamar Router1, wannan na'ura mai ba da hanya tsakanin hanyoyin sadarwa yana ƙoƙarin kafa alaƙar kusanci da Router3. Ana kiran yanayin farko lokacin da babu abin da ya faru malalaci. Da zaran an saita bgp akan Router1, zai fara sauraron tashar TCP 179 - zai shiga cikin jihar. connect, kuma lokacin da yayi ƙoƙarin buɗe taro tare da Router3, zai shiga cikin jihar Active.

Bayan an kafa zaman tsakanin Router1 da Router3, Buɗe saƙonni ana musayar. Lokacin da Router1 ya aika wannan sakon, za a kira wannan jihar Buɗe An aika. Kuma idan ya sami Buɗaɗɗen saƙo daga Router3, zai shiga cikin jihar Bude Tabbatarwa. Mu kalli Bude sakon:

Wannan saƙon yana isar da bayanai game da ƙa'idar BGP kanta, wacce na'ura mai ba da hanya tsakanin hanyoyin sadarwa ke amfani da ita. Ta hanyar musayar buɗaɗɗen saƙonni, Router1 da Router3 suna sadar da bayanai game da saitunan su ga juna. An wuce waɗannan sigogi masu zuwa:

• version: wannan ya haɗa da nau'in BGP da na'ura mai ba da hanya tsakanin hanyoyin sadarwa ke amfani da ita. Nau'in BGP na yanzu shine nau'i na 4 wanda aka bayyana a cikin RFC 4271. Na'urorin BGP guda biyu za su yi ƙoƙarin yin shawarwarin sigar da ta dace, idan aka sami rashin daidaituwa to ba za a yi zaman BGP ba.
• AS ku: wannan ya hada da lambar AS na BGP router, masu amfani da hanyar sadarwa za su amince da lambar AS kuma ya bayyana ko za su yi aiki da iBGP ko eBGP.
• Riƙe Lokaci: idan BGP ba ta sami wani adanawa ko sabunta saƙon daga ɗayan ɓangaren ba na tsawon lokacin riƙon to zai ayyana ɗayan 'matattu' kuma zai rushe zaman BGP. Ta tsohuwa an saita lokacin riƙewa zuwa daƙiƙa 180 akan masu amfani da hanyar sadarwa na Cisco IOS, ana aika saƙon kiyayewa kowane sakan 60. Duk hanyoyin sadarwa biyu dole ne su yarda akan lokacin riƙon ko kuma ba za a yi zaman BGP ba.
• Mai gano BGP: wannan shine ID na na'ura mai ba da hanya tsakanin hanyoyin sadarwa na BGP na gida wanda aka zaba kamar yadda OSPF ke yi:
  • Yi amfani da hanyar sadarwa-ID wanda aka saita da hannu tare da umarnin bgp router-id.
  • Yi amfani da adireshin IP mafi girma akan madaidaicin madauki.
  • Yi amfani da adireshin IP mafi girma akan mahallin mahallin jiki.
• Ma'auni na zaɓi: anan za ku sami wasu damar zaɓi na na'ura mai ba da hanya tsakanin hanyoyin sadarwa na BGP. An ƙara wannan filin don a iya ƙara sababbin abubuwa zuwa BGP ba tare da ƙirƙirar sabon salo ba. Abubuwan da za ku iya samu a nan su ne:
  • goyon bayan MP-BGP (Multi Protocol BGP).
  • goyan baya don Refresh na Hanya.
  • goyan bayan lambobin AS 4-octet.

Don kafa unguwa, dole ne a cika waɗannan sharuɗɗa:

• Lambar sigar. Nau'in na yanzu shine 4.
• Dole ne lambar AS ta dace da abin da kuka tsara makwabta 192.168.13.3 nesa-kamar 10.
• ID na na'ura mai ba da hanya tsakanin hanyoyin sadarwa dole ne ya bambanta da maƙwabci.

Idan kowane sigogi bai gamsar da waɗannan sharuɗɗan ba, na'ura mai ba da hanya tsakanin hanyoyin sadarwa zai aika Sanarwa sakon da ke nuna kuskure. Bayan aikawa da karɓar buɗaɗɗen saƙonni, dangantakar makwabta ta shiga cikin jihar KYAUTA. Bayan haka, masu amfani da hanyar sadarwa zasu iya musayar bayanai game da hanyoyi kuma suyi haka ta amfani da su Update saƙonni. Wannan shine saƙon Ɗaukakawa da Router1 ya aika zuwa Router3:

Anan zaku iya ganin hanyoyin sadarwar da Router1 da sifofin Hanya suka ruwaito, waɗanda suke kama da awo. Za mu yi magana game da halayen Tafarki daki-daki. Hakanan ana aika saƙonnin Keepalive a cikin zaman TCP. Ana watsa su, ta tsohuwa, kowane sakan 60. Wannan Kebealive Timer ne. Idan ba a karɓi saƙon Keepalive a lokacin Riƙe Timer ba, wannan yana nufin asarar sadarwa tare da maƙwabci. Ta hanyar tsoho, yana daidai da 180 seconds.

Alama mai amfani:

Da alama mun gano yadda masu amfani da hanyoyin sadarwa ke watsa bayanai ga junansu, yanzu bari mu yi ƙoƙari mu fahimci ma'anar ka'idar BGP.

Don tallata hanya zuwa teburin BGP, kamar yadda yake a cikin ka'idojin IGP, ana amfani da umarnin hanyar sadarwa, amma dabaru na aiki sun bambanta. Idan a cikin IGP, bayan tantance hanyar a cikin umarnin cibiyar sadarwa, IGP yana duba waɗanne musaya ne na wannan rukunin yanar gizon kuma ya haɗa su a cikin tebur ɗin sa, to, umarnin cibiyar sadarwa a cikin BGP yana duban tebur ɗin ya nemi. daidai yayi daidai da hanya a cikin umarnin cibiyar sadarwa. Idan an sami irin wannan, waɗannan hanyoyin za su bayyana a teburin BGP.

Nemo hanya a cikin tebur mai tuƙi na IP na na'ura mai ba da hanya tsakanin hanyoyin sadarwa wanda ya dace daidai da sigogin umarnin cibiyar sadarwa; idan hanyar IP ta wanzu, sanya NLRI daidai a cikin teburin BGP na gida.

Yanzu bari mu ɗaga BGP zuwa duk sauran kuma mu ga yadda aka zaɓi hanyar a cikin AS guda ɗaya. Bayan da BGP na'ura mai ba da hanya tsakanin hanyoyin sadarwa ya karɓi hanyoyi daga maƙwabcinsa, ya fara zaɓar hanya mafi kyau. A nan kana buƙatar fahimtar irin nau'in maƙwabta za a iya zama - ciki da waje. Shin na'ura mai ba da hanya tsakanin hanyoyin sadarwa ya gane ta hanyar daidaitawa ko maƙwabcin da aka saita yana ciki ko na waje? Idan a cikin ƙungiya:

neighbor 192.168.13.3 remote-as 10 

Remote-kamar yadda ma'auni ya ƙayyade AS, wanda aka saita a kan na'ura mai ba da hanya tsakanin hanyoyin sadarwa da kansa a cikin umarnin bgp 10. Hanyoyin da ke fitowa daga AS na ciki ana daukar su a ciki, kuma hanyoyin daga AS na waje ana daukar su a waje. Kuma ga kowane, dabaru daban-daban na karba da aika ayyukan. Yi la'akari da wannan topology:

Kowane na'ura mai ba da hanya tsakanin hanyoyin sadarwa yana da madaidaicin madauki wanda aka saita shi tare da ip: xxxx 255.255.255.0 - inda x shine lambar na'ura mai ba da hanya tsakanin hanyoyin sadarwa. A kan Router9 muna da madaidaicin madauki tare da adireshin - 9.9.9.9 255.255.255.0. Za mu sanar da shi ta hanyar BGP kuma mu ga yadda yake yaduwa. Za a watsa wannan hanyar zuwa Router8 da Router12. Daga Router8, wannan hanya za ta je Router6, amma zuwa Router5 ba zai kasance a cikin tebur mai ba da hanya ba. Hakanan akan Router12 wannan hanyar zata bayyana a cikin tebur, amma akan Router11 shima ba zai kasance a can ba. Mu yi kokarin gano wannan. Bari mu yi la'akari da abin da bayanai da sigogi Router9 ke watsawa ga maƙwabtansa, yana ba da rahoton wannan hanya. Za a aika fakitin da ke ƙasa daga Router9 zuwa Router8.

Bayanin hanya ya ƙunshi halayen Tafarki.

An raba halayen hanya zuwa rukuni 4:

1. Sanannen tilas - Duk masu amfani da hanyar sadarwa da ke tafiyar da BGP dole ne su gane waɗannan halayen. Dole ne ya kasance a cikin duk sabuntawa.
2. Sanannen hankali - Duk masu amfani da hanyar sadarwa da ke tafiyar da BGP dole ne su gane waɗannan halayen. Suna iya kasancewa a cikin sabuntawa, amma ba a buƙatar kasancewar su.
3. Mai wucewa na zaɓi - ƙila ba za a iya gane su ta duk aiwatar da BGP ba. Idan mai amfani da na'ura mai ba da hanya tsakanin hanyoyin sadarwa bai gane sifa ba, yana nuna alamar sabuntawa a matsayin wani ɓangare kuma ya tura shi zuwa maƙwabtansa, yana adana sifa da ba a gane ba.
4. Na zaɓi mara canzawa - ƙila ba za a iya gane su ta duk aiwatar da BGP ba. Idan na'ura mai ba da hanya tsakanin hanyoyin sadarwa bai gane sifa ba, to, an yi watsi da sifa kuma a watsar da shi lokacin da aka mika shi ga makwabta.

Misalan halayen BGP:

• Sanannen tilas:
  • Hanyar tsarin mai cin gashin kansa
  • Next-hop
  • Origin

• Sanannen hankali:
  • Zaɓin gida
  • Atomic tara
• Mai wucewa na zaɓi:
  • Mai tarawa
  • Ƙungiyoyin
• Na zaɓi mara canzawa:
  • Mai nuna wariya da yawa (MED)
  • ID na asali
  • Jerin gungu

A wannan yanayin, a yanzu za mu yi sha'awar Origin, Next-hop, AS Path. Tun da hanyar ke watsawa tsakanin Router8 da Router9, wato, a cikin AS guda ɗaya, ana la'akari da shi a ciki kuma za mu kula da Origin.

Asalin asali - yana nuna yadda aka sami hanyar a cikin sabuntawa. Ƙimar sifa mai yiwuwa:

• 0 - IGP: NLRI da aka karɓa a cikin tsarin asali na asali;
• 1 - EGP: Ana koyan NLRI ta hanyar amfani da ka'idar Ƙofar Ƙofar waje (EGP). Magabata zuwa BGP, ba a yi amfani da shi ba
• 2 - Rashin cikawa: An koyi NLRI ta wata hanya dabam

A cikin yanayinmu, kamar yadda ake iya gani daga fakiti, yana daidai da 0. Lokacin da aka aika wannan hanyar zuwa Router12, wannan lambar zata sami lambar 1.

Na gaba, Next-hop. Sifa ta gaba-hop

• Wannan shine adireshin IP na eBGP na'ura mai ba da hanya tsakanin hanyoyin sadarwa wanda hanyar zuwa cibiyar sadarwar da aka nufa ta shiga.
• Siffar tana canzawa lokacin da aka aika prefix zuwa wani AS.

Game da iBGP, wato, a cikin AS guda ɗaya, Next-hop zai nuna wanda ya koya ko ya faɗa game da wannan hanya. A cikin yanayinmu, zai zama 192.168.89.9. Amma lokacin da aka watsa wannan hanya daga Router8 zuwa Router6, Router8 zai canza shi kuma ya maye gurbinsa da nasa. Next-hop zai zama 192.168.68.8. Wannan ya kai mu ga dokoki guda biyu:

1. Idan na'ura mai ba da hanya tsakanin hanyoyin sadarwa ya tura hanya zuwa makwabcinsa na ciki, ba zai canza ma'aunin Next-hop ba.
2. Idan na'ura mai ba da hanya tsakanin hanyoyin sadarwa ya aika hanya zuwa maƙwabcinsa na waje, yana canza Next-hop zuwa ip na interface wanda wannan na'ura mai ba da hanya tsakanin hanyoyin sadarwa ke watsawa.

Wannan yana ba mu damar fahimtar matsala ta farko - Me yasa ba za a sami wata hanya a cikin tebur mai ba da hanya ba akan Router5 da Router11. Mu duba sosai. Don haka, Router6 ya karɓi bayanai game da hanyar 9.9.9.0/24 kuma ya sami nasarar ƙara shi zuwa teburin kwatance:

Router6#show ip route bgp
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
       a - application route
       + - replicated route, % - next hop override, p - overrides from PfR

Gateway of last resort is not set

      9.0.0.0/24 is subnetted, 1 subnets
B        9.9.9.0 [20/0] via 192.168.68.8, 00:38:25<source>
Теперь Router6 передал маршрут Router5 и первому правилу Next-hop не изменил. То есть, Router5 должен добавить  <b>9.9.9.0 [20/0] via 192.168.68.8</b> , но у него нет маршрута до 192.168.68.8 и поэтому данный маршрут добавлен не будет, хотя информация о данном маршруте будет храниться в таблице BGP:

<source><b>Router5#show ip bgp
BGP table version is 1, local router ID is 5.5.5.5
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
              x best-external, a additional-path, c RIB-compressed,
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

     Network          Next Hop            Metric LocPrf Weight Path
 * i 9.9.9.0/24       192.168.68.8             0    100      0 45 i</b>

Hakanan yanayin zai faru tsakanin Router11-Router12. Don guje wa wannan yanayin, kuna buƙatar saita Router6 ko Router12, lokacin wucewa zuwa maƙwabta na ciki, don maye gurbin adireshin IP ɗin su azaman Next-hop. Ana yin wannan ta amfani da umarnin:

neighbor 192.168.56.5 next-hop-self

Bayan wannan umarni, Router6 zai aika saƙon Ɗaukakawa, inda za a ƙayyade ip na interface Gi0/0 Router6 a matsayin Next-hop don hanyoyi - 192.168.56.6, bayan haka wannan hanya za a riga an haɗa shi a cikin tebur.

Bari mu ci gaba don ganin idan wannan hanyar ta bayyana akan Router7 da Router10. Ba zai kasance a cikin tebur mai ba da hanya ba kuma muna iya tunanin cewa matsalar daidai take da na farko tare da madaidaicin Next-hop, amma idan muka kalli fitowar ip bgp umurnin, za mu ga cewa Ba a karɓi hanyar a can ba ko da da kuskuren Next-hop, wanda ke nufin cewa ba a ma watsa hanyar ba. Kuma wannan zai kai mu ga samuwar wata ka’ida:

Hanyoyin da aka karɓa daga maƙwabta na ciki ba a yada su zuwa wasu maƙwabta na ciki.

Tun da Router5 ya karɓi hanyar daga Router6, ba za a watsa shi zuwa sauran maƙwabcinsa na ciki ba. Domin canja wurin ya faru, kuna buƙatar saita aikin Hanyar Hannu, ko saita cikakkiyar alaƙar unguwanni masu alaƙa (Full Mesh), wato, Router5-7 kowa zai zama maƙwabci ga kowa. A wannan yanayin za mu yi amfani da Route Reflector. A kan Router5 kuna buƙatar amfani da wannan umarni:

neighbor 192.168.57.7 route-reflector-client

Route-Reflector yana canza halayen BGP lokacin wucewa ta hanya zuwa maƙwabcin ciki. Idan an ƙayyade maƙwabcin ciki kamar hanya-mai nuni-abokin ciniki, sannan za a tallata hanyoyin ciki ga waɗannan abokan ciniki.

Hanyar ba ta bayyana akan Router7 ba? Kar ku manta game da Next-hop ko dai. Bayan waɗannan magudi, hanya kuma yakamata ta tafi zuwa Router7, amma hakan bai faru ba. Wannan ya kawo mu ga wata ka'ida:

Dokar gaba-hop tana aiki ne kawai don hanyoyin waje. Don hanyoyin ciki, ba a maye gurbin sifa ta gaba.

Kuma muna samun yanayin da ya zama dole don ƙirƙirar yanayi ta hanyar amfani da ka'idodin tsarin aiki na tsaye ko IGP don sanar da masu amfani da hanyoyin sadarwa game da duk hanyoyin da ke cikin AS. Bari mu yi rajista a tsaye a kan Router6 da Router7 kuma bayan haka za mu sami hanyar da ake so a cikin tebur na na'ura mai ba da hanya tsakanin hanyoyin sadarwa. A AS 678, za mu yi shi kadan daban-daban - za mu yi rajista a tsaye hanyoyi don 192.168.112.0/24 akan Router10 da 192.168.110.0/24 akan Router12. Na gaba, za mu kafa dangantakar makwabta tsakanin Router10 da Router12. Za mu kuma saita Router12 don aika saƙo na gaba zuwa Router10:

neighbor 192.168.110.10 next-hop-self

Sakamakon zai zama cewa Router10 zai karɓi hanya 9.9.9.0/24, za a karɓa daga duka Router7 da Router12. Bari mu ga abin da Router10 ya yi:

Router10#show ip bgp
BGP table version is 3, local router ID is 6.6.6.6
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
              x best-external, a additional-path, c RIB-compressed,
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

     Network              Next Hop            Metric LocPrf Weight Path
 *>i 9.9.9.0/24       192.168.112.12           0    100       0      45 i

                               192.168.107.7                                0     123 45 i  

Kamar yadda muke iya gani, hanyoyi biyu da kibiya (>) suna nufin cewa an zaɓi hanyar ta hanyar 192.168.112.12.
Bari mu ga yadda tsarin zaɓin hanya ke aiki:

1. Mataki na farko lokacin karɓar hanya shine bincika samuwar Next-hop ɗin sa. Abin da ya sa, lokacin da muka sami hanya akan Router5 ba tare da saita Next-hop-self ba, wannan hanyar ba ta ƙara sarrafa ba.
2. Na gaba ya zo ma'aunin nauyi. Wannan sigar ba sifa ta Hanya ba ce (PA) kuma ba a aika ta cikin saƙonnin BGP ba. An saita shi a cikin gida akan kowane na'ura mai ba da hanya tsakanin hanyoyin sadarwa kuma ana amfani dashi kawai don sarrafa zaɓin hanya akan na'ura mai ba da hanya tsakanin hanyoyin sadarwa da kanta. Bari mu kalli misali. A sama zaku iya ganin cewa Router10 ya zaɓi hanya don 9.9.9.0/24 ta hanyar Router12 (192.168.112.12). Don canza ma'aunin Wieight, zaku iya amfani da taswirar hanya don saita takamaiman hanyoyi, ko sanya nauyi ga maƙwabcinsa ta amfani da umarnin:

    neighbor 192.168.107.7 weight 200       

   Yanzu duk hanyoyi daga wannan maƙwabcin za su sami wannan nauyin. Bari mu ga yadda zaɓin hanyar ke canzawa bayan wannan magudi:

   Router10#show bgp
   *Mar  2 11:58:13.956: %SYS-5-CONFIG_I: Configured from console by console
   BGP table version is 2, local router ID is 6.6.6.6
   Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
                 r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
                 x best-external, a additional-path, c RIB-compressed,
   Origin codes: i - IGP, e - EGP, ? - incomplete
   RPKI validation codes: V valid, I invalid, N Not found
   
        Network          Next Hop            Metric LocPrf Weight      Path
    *>  9.9.9.0/24       192.168.107.7                        200      123 45 i
    * i                          192.168.112.12           0          100      0 45 i

   Kamar yadda kake gani, hanyar ta hanyar Router7 yanzu an zaɓi, amma wannan ba zai yi wani tasiri a kan sauran hanyoyin ba.

3. A matsayi na uku muna da Preference Local. Wannan siga sanannen sifa ce ta hankali, wanda ke nufin kasancewarsa na zaɓi ne. Wannan siga yana aiki ne kawai a cikin AS guda ɗaya kuma yana shafar zaɓin hanyar kawai don maƙwabta na ciki. Shi ya sa ake watsa shi a cikin Sabunta saƙonnin da aka yi nufin maƙwabcin ciki. Babu a cikin Sabunta saƙonni don maƙwabta na waje. Saboda haka, an kasafta shi a matsayin Sanannen hankali. Bari mu gwada amfani da shi akan Router5. A kan Router5 ya kamata mu sami hanyoyi guda biyu don 9.9.9.0/24 - ɗaya ta hanyar Router6 da na biyu ta hanyar Router7.

   Mun duba:

   Router5#show bgp
   BGP table version is 2, local router ID is 5.5.5.5
   Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
                 r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
                 x best-external, a additional-path, c RIB-compressed,
   Origin codes: i - IGP, e - EGP, ? - incomplete
   RPKI validation codes: V valid, I invalid, N Not found
   
        Network          Next Hop            Metric LocPrf Weight Path
    *>i 9.9.9.0/24       192.168.56.6             0    100      0 45 i

   Amma kamar yadda muka ga hanya ɗaya ta hanyar Router6. Ina hanyar ta hanyar Router7? Wataƙila Router7 ba shi da shi kuma? Mu duba:

   Router#show bgp
   BGP table version is 10, local router ID is 7.7.7.7
   Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
                 r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
                 x best-external, a additional-path, c RIB-compressed,
   Origin codes: i - IGP, e - EGP, ? - incomplete
   RPKI validation codes: V valid, I invalid, N Not found
   
        Network                Next Hop            Metric LocPrf  Weight    Path
    *>i 9.9.9.0/24       192.168.56.6             0     100           0      45 i
   
                                 192.168.107.10                                  0     678 45 i 

   M, duk abin da alama yana da kyau. Me yasa ba a watsa shi zuwa Router5? Abun shine BGP yana da ka'ida:

   Na'ura mai ba da hanya tsakanin hanyoyin sadarwa yana watsa kawai waɗancan hanyoyin da yake amfani da su.

   Router7 yana amfani da hanya ta hanyar Router5, don haka hanyar ta hanyar Router10 ba za a watsa ba. Mu koma zuwa Zaɓin Gida. Bari mu saita zaɓi na gida akan Router7 kuma mu ga yadda Router5 ke amsawa ga wannan:

   route-map BGP permit 10
    match ip address 10
    set local-preference 250
   access-list 10 permit any
   router bgp 123
    neighbor 192.168.107.10 route-map BGP in</b>

   Don haka, mun ƙirƙiri taswirar hanya wacce ta ƙunshi duk hanyoyin kuma mun gaya wa Router7 don canza madaidaicin fifiko na gida zuwa 250 lokacin da aka karɓa, tsoho shine 100. Bari mu ga abin da ya faru akan Router5:

   Router5#show bgp
   BGP table version is 8, local router ID is 5.5.5.5
   Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
                 r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
                 x best-external, a additional-path, c RIB-compressed,
   Origin codes: i - IGP, e - EGP, ? - incomplete
   RPKI validation codes: V valid, I invalid, N Not found
   
        Network          Next Hop            Metric LocPrf Weight        Path
    *>i 9.9.9.0/24       192.168.57.7             0          250      0 678 45 i

   Kamar yadda muke iya gani yanzu Router5 ya fi son hanyar ta hanyar Router7. Hoton iri ɗaya zai kasance akan Router6, kodayake yana da fa'ida a gare shi don zaɓar hanya ta hanyar Router8. Mun kuma ƙara da cewa canza wannan siga yana buƙatar sake kunna unguwar don canjin ya yi tasiri. Karanta a nan. Mun tsara zaɓin Gida. Bari mu matsa zuwa siga na gaba.

4. Fi son hanyar tare da ma'aunin Next-hop 0.0.0.0, wato, hanyoyin gida ko tara. Ana sanya waɗannan hanyoyin ta atomatik ma'aunin nauyi daidai da matsakaicin-32678-bayan shigar da umarnin cibiyar sadarwa:

   Router#show bgp
   BGP table version is 2, local router ID is 9.9.9.9
   Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
                 r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
                 x best-external, a additional-path, c RIB-compressed,
   Origin codes: i - IGP, e - EGP, ? - incomplete
   RPKI validation codes: V valid, I invalid, N Not found
   
        Network          Next Hop            Metric LocPrf Weight    Path
    *>  9.9.9.0/24       0.0.0.0                  0            32768    i

5. Hanya mafi guntu ta hanyar AS. An zaɓi mafi ƙarancin siga AS_Path. Ƙananan ASs hanyar da ke bi, mafi kyau shine. Yi la'akari da hanyar zuwa 9.9.9.0/24 akan Router10:

   Router10#show bgp
   BGP table version is 2, local router ID is 6.6.6.6
   Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
                 r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
                 x best-external, a additional-path, c RIB-compressed,
   Origin codes: i - IGP, e - EGP, ? - incomplete
   RPKI validation codes: V valid, I invalid, N Not found
   
        Network          Next Hop            Metric LocPrf Weight Path
    *   9.9.9.0/24     192.168.107.7                           0           123 45 i
    *>i                     192.168.112.12           0    100       0       45 i

   Kamar yadda kake gani, Router10 ya zaɓi hanyar ta hanyar 192.168.112.12 saboda wannan hanyar AS_Path siga ya ƙunshi kawai 45, kuma a wani yanayin 123 da 45. A bayyane yake.

6. Siga na gaba shine Asalin. IGP (hanyar da aka samu ta amfani da BGP) ta fi EGP (hanyar da aka samu ta hanyar amfani da magabata na BGP, ba a amfani da ita), kuma EGP ya fi Incomplete? (samuwar ta wata hanyar, misali ta hanyar sake rarrabawa).
7. Siga na gaba shine MED. Muna da Wieight wanda kawai ke aiki a gida akan na'ura mai ba da hanya tsakanin hanyoyin sadarwa. Akwai Zaɓin Gida, wanda kawai yayi aiki a cikin tsari ɗaya mai cin gashin kansa. Kamar yadda zaku iya tsammani, MED siga ce wacce za'a watsa tsakanin tsarin mai cin gashin kansa. Yayi kyau sosai labarin game da wannan siga.

Ba za a sake amfani da sifofi ba, amma idan hanyoyi biyu suna da halaye iri ɗaya, to ana amfani da waɗannan ƙa'idodi:

1. Zaɓi hanyar ta maƙwabcin IGP mafi kusa.
2. Zaɓi hanya mafi tsufa don hanyar eBGP.
3. Zaɓi hanyar ta maƙwabci tare da mafi ƙarancin ID na hanyar sadarwa na BGP.
4. Zaɓi hanya ta maƙwabci tare da mafi ƙarancin adireshin IP.

Yanzu bari mu kalli batun haduwar BGP.

Bari mu ga abin da zai faru idan Router6 ya rasa hanyar 9.9.9.0/24 ta hanyar Router9. Bari mu musaki haɗin Gi0/1 na Router6, wanda nan da nan zai fahimci cewa an ƙare zaman BGP tare da Router8 kuma maƙwabcin ya ɓace, wanda ke nufin hanyar da aka karɓa daga gare ta ba ta da inganci. Nan take Router6 ya aika da Sabunta saƙon, inda yake nuna hanyar sadarwar 9.9.9.0/24 a cikin filin Wayar da Hannu. Da zarar Router5 ya sami irin wannan saƙon, zai aika zuwa Router7. Amma tunda Router7 yana da hanya ta hanyar Router10, nan take zai amsa tare da Sabuntawa tare da sabuwar hanya. Idan ba zai yiwu a gano faɗuwar maƙwabci ba bisa ga yanayin haɗin yanar gizon, to dole ne ku jira Rike Timer ya ƙone.

Tarayyar.

Idan kun tuna, mun yi magana game da gaskiyar cewa sau da yawa dole ne ku yi amfani da cikakken haɗin kai. Tare da yawancin hanyoyin sadarwa a cikin AS ɗaya wannan na iya haifar da manyan matsaloli, don guje wa wannan kuna buƙatar amfani da ƙungiyoyi. An raba AS ɗaya zuwa ƙananan-AS da yawa, wanda ke ba su damar yin aiki ba tare da buƙatar cikakken haɗin kai ba.

Ga hanyar haɗi zuwa wannan labuda kuma a nan Saukewa: GNS3.

Misali, tare da wannan topology dole ne mu haɗa dukkan hanyoyin sadarwa a cikin AS 2345 zuwa juna, amma ta amfani da Confederation, za mu iya kafa alaƙar kusanci tsakanin masu amfani da hanyar sadarwa kai tsaye da juna. Bari mu yi magana game da wannan daki-daki. Idan muna da AS 2345 kawai, to laForge bayan sun samu tattaki daga Picard zai gaya wa masu amfani da hanyar sadarwa data и Aikin, amma ba za su gaya wa na'ura mai ba da hanya tsakanin hanyoyin sadarwa ba Crusher . Hakanan hanyoyin da na'ura mai ba da hanya tsakanin hanyoyin sadarwa ke rarrabawa kanta laForge, da ba a canjawa wuri ba Crusher ba kuma Aikin- ba, ba data.

Dole ne ku saita Hanyar-Reflector ko alaƙar unguwar da ke da alaƙa. Ta hanyar rarraba AS 2345 guda ɗaya zuwa 4 sub-AS (2,3,4,5) ga kowane mai amfani da na'ura mai ba da hanya tsakanin hanyoyin sadarwa, zamu ƙare da dabaru na aiki daban-daban. An kwatanta komai daidai a nan.

Sources:

1. CCIE Routing da Sauyawa v5.0 Jagoran Takaddar Hukuma, Juzu'i na 2, Buga na Biyar, Narbik Kocharians, Terry Vinson.
2. website xgu.ru
3. website Farashin GNS3V.

source: www.habr.com