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Quagga pe Linux

Quagga este o suita de software de rutare, care ofera implementari de OSPFv2, OSPFv3, RIP v1 si v2, RIPng si BGP-4 pentru platformele Unix, in special FreeBSD, Linux, Solaris si NetBSD. Quagga este un fork a GNU Zebra care a fost dezvoltata de Kunihiro Ishiguro.

Arhitectura Quagga consta dintr-un demon de baza, zebra , care actioneaza ca un strat de abstractizare a nucleului subunitar Unix si prezinta API-ul Zserv peste un flux Unix sau TCP clientilor Quagga. Acesti clienti Zserv implementeaza de obicei un protocol de rutare si comunica actualizari de rutare catre demonul zebra.

BGP4 RFC: RFC 1772

Folosirea BGP presupune:
* detinerea unui [http://en.wikipedia.org/wiki/Autonomous_system_%28Internet%29 Autonomous System Number], pe scurt AS
* detinerea unui subnet /24 (sau mai mic) de adrese IP Provider Independent, pe scurt PI

== Exemple practice ==

Pentru a seta o sesiune BGP intre 2 neighbori (presupunand ca aveti routerele A si B si AS-urile: 65534 si 65535) faceti in felul urmator:

Router A:

RouterA# configure terminal
RouterA(config)# router bgp 65534
RouterA(config-router)# network 10.2.2.0
RouterA(config-router)# neighbor 10.1.2.2 remote-as 65535
RouterA(config-router)# neighbor 10.1.2.2 description RouterB
RouterA# write memory

Router B:

RouterB# configure terminal
RouterB(config)# router bgp 65535
RouterB(config-router)# network 10.2.3.0
RouterB(config-router)# neighbor 10.1.2.1 remote-as 65534
RouterB(config-router)# neighbor 10.1.2.1 description RouterA
RouterB# write memory

In exemplul de mai sus, fiecare router anunta cate un prefix /24 (pentru prefixe mai lungi se trece masca de retea in format [http://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing CIDR]).

Daca in ecuatia de mai sus se mai adauga un Router C astfel incat sa avem topologia urmatoare
RouterA <--> RouterB <--> RouterC
atunci configuratia se modifica dupa cum urmeaza:

Router B:

RouterB# configure terminal
RouterB(config)# router bgp 65535
RouterB(config-router)# network 10.2.3.0
RouterB(config-router)# neighbor 10.1.2.1 remote-as 65534
RouterB(config-router)# neighbor 10.1.2.1 description RouterA
RouterB(config-router)# neighbor 10.1.2.6 remote-as 65533
RouterB(config-router)# neighbor 10.1.2.6 description RouterC
RouterB# write memory

Router C:

RouterC# configure terminal
RouterC(config)# router bgp 65533
RouterC(config-router)# network 10.2.4.0
RouterC(config-router)# neighbor 10.1.2.5 remote-as 65535
RouterC(config-router)# neighbor 10.1.2.5 description RouterB
RouterC# write memory

Daca vrem ca (e.g.) RouterB sa fie default gateway pentru celelalte doua routere, procedam dupa cum urmeaza:

RouterB# configure terminal
RouterB(config)# router bgp 65535
RouterB(config-router)# network 10.2.3.0
RouterB(config-router)# neighbor 10.1.2.1 remote-as 65534
RouterB(config-router)# neighbor 10.1.2.1 default-originate
RouterB(config-router)# neighbor 10.1.2.1 description RouterA
RouterB(config-router)# neighbor 10.1.2.6 remote-as 65533
RouterB(config-router)# neighbor 10.1.2.6 default-originate
RouterB(config-router)# neighbor 10.1.2.6 description RouterC
RouterB# write memory

Folosind default-originate, pe langa prefixele exportate, se va mai exporta si 0.0.0.0/0.

Cam pana aici au fost configurarile de baza, mai jos veti gasi exemple de configurare putin mai complexe (i.e.: prefix-lists, as-prepend etc)

Pentru a nu accepta ruta default de la un anumit neighbor se face asa:

RouterC# configure terminal
RouterC(config)# ip prefix-list NO-DEFAULT seq 5 deny 0.0.0.0/0 le 1
RouterC(config)# ip prefix-list NO-DEFAULT seq 10 permit any
RouterC(config)# router bgp 65533
RouterC(config-router)# neighbor 10.1.2.5 remote-as 65535
RouterC(config-router)# neighbor 10.1.2.5 description RouterB
RouterC(config-router)# neighbor 10.1.2.5 prefix-list NO-DEFAULT in
RouterC# clear ip bgp 10.1.2.5 soft in
RouterC# write memory

Daca nu vreti sa deveniti transit provider pentru altii, e bine sa stiti ce anume exportati la alti neighbori:

RouterB# configure terminal
RouterB(config)# ip prefix-list our-subnets seq 10 permit 10.2.3.0/24
RouterB(config)# ip prefix-list our-subnets seq 20 deny any any
RouterB(config)# router bgp 65535
RouterB(config-router)# network 10.2.3.0
RouterB(config-router)# neighbor 10.1.2.1 remote-as 65534
RouterB(config-router)# neighbor 10.1.2.1 default-originate
RouterB(config-router)# neighbor 10.1.2.1 prefix-list our-subnets out
RouterB(config-router)# neighbor 10.1.2.1 description RouterA
RouterB(config-router)# neighbor 10.1.2.6 remote-as 65533
RouterB(config-router)# neighbor 10.1.2.6 default-originate
RouterB(config-router)# neighbor 10.1.2.6 prefix-list our-subnets out
RouterB(config-router)# neighbor 10.1.2.6 description RouterC
routerB# clear ip bgp * soft out
RouterB# write memory

Bafta!

Andreea

"Rome wasn't built in a day" !
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