Contents

BGP 기본 구성 / 방법 1, 방법 2

   Jan 10, 2023     7 min read

BGP



1

BGP AS 100 = ex. SKT
BGP AS 200 = ex. LG U+
서로 간 협약(계약)을 하게 만들고 싶다.


방법 - 명령어



R1)
    router bgp 100
    bgr router-id 1.1.1.1
    neighbor 1.1.12.2 remote-as 100
    network 192.168.10.0 mask 255.255.255.0 <- 자신의 라우터에 해당된 PC의 정보만 넣어주면 된다는 것을 기억하자.(보통 회사 쪽에 있는 네트워크만 넣어줌.)

R2)
    router bgp 100
    bgp router-id 2.2.2.2
    neighbor 1.1.12.1 remote-as 100
    network 192.168.20.0 mask 255.255.255.0

R3)
    router bgp 200
    bgp router-id 3.3.3.3
    neighbor 3.3.12.2 remote-as 200
    network 192.168.30.0 mask 255.255.255.0

R4)
    router bgp 200
    bgp router-id 4.4.4.4
    neighbor 3.3.12.1 remote-as 200
    network 192.168.40.0 mask 255.255.255.0




# show ip bgp



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iBGP


같은 BGP 내에서 교환하는 것을 의미함.

eBGP


다른 AS 간 교환.

명령어 - 방법 1.



R2)
    router bgp 100
    neighbor 2.2.12.2 remote-as 200

R3)
    router bgp 200
    neighbor 2.2.12.1 remote-as 100




# show ip bgp




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B라고 뜬 것을 확인할 수 있음.
이것을 우리는 BGP로 교환한 것을 알 수 있음.

11
역시 R3에서도 B라고 뜸.

12
192.168.10.1 에서 아까는 안 되던 30.1과 40.1로의 ping이 됨.



DMZ 구간 - 2.2.12.0



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2.2.12.0은 누구의 소유도 아니다.


# show ip bgp summary


neighbor 확인

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방법 02. - 명령어 (ft. 상대 원칙)




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R1)
    ip route 3.3.3.0 255.255.255.0 1.1.12.2 <- 상대 원칙

    router bgp 100
    bgp router-id 1.1.1.1
    neighbor 2.2.2.2 remote-as 100
    neighbor 2.2.2.2 update-source lo 0
    network 192.168.10.0 mask 255.255.255.0

R2)
    ip route 3.3.3.0 255.255.255.0 2.2.12.2

    router bgp 100
    bgp router-id 2.2.2.2
    neighbor 1.1.1.1 remote-as 100
    neighbor 1.1.1.1 update-source lo 0
    neighbor 3.3.3.3 remote-as 200
    neighbor 3.3.3.3 update-source lo 0
    neighbor 3.3.3.3 ebgp-multihop 2
    network 192.168.20.0 mask 255.255.255.0

R3)
    ip route 2.2.2.0 255.255.255.0 2.2.12.1

    router bgp 200
    bgp router-id 3.3.3.3
    neighbor 4.4.4.4 remote-as 200
    neighbor 4.4.4.4 update-source lo 0
    neighbor 2.2.2.2 remote-as 100
    neighbor 2.2.2.2 update-source lo 0
    neighbor 2.2.2.2 ebgp-multihop 2
    network 192.168.30.0 mask 255.255.255.0

R4)
    ip route 2.2.2.0 255.255.255.0 3.3.12.1 <- 상대 원칙
    
    router bgp 200
    bgp router-id 4.4.4.4
    neighbor 3.3.3.3 remote-as 200
    neighbor 3.3.3.3 update-source lo 0
    network 192.168.40.0 mask 255.255.255.0




결과.



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Ex. 유형 01



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물리적으로 직접 붙어있는 것으로 neighbor을 주기.


방법.



R1)
    router bgp 100
    bgp router-id 1.1.1.1
    neighbor 1.1.12.2 remote-as 100
    network 192.168.10.0 mask 255.255.255.0

R2)
    router bgp 100
    bgp router-id 2.2.2.2
    neighbor 1.1.12.1 remote-as 100
    network 192.168.20.0 mask 255.255.255.0
    neighbor 2.2.12.3 remote-as 200

R3)
    router bgp 200
    bgp router-id 3.3.3.3
    neighbor 3.3.12.4 remote-as 200
    network 192.168.30.0 mask 255.255.255.0
    neighbor 2.2.12.2 remote-as 100

R4)
    router bgp 200
    bgp router-id 4.4.4.4
    neighbor 3.3.12.3 remote-as 200
    network 192.168.40.0 mask 255.255.255.0
    neighbor 4.4.12.5 remote-as 300

R5)
    router bgp 300
    bgp router-id 5.5.5.5
    neighbor 5.5.12.6 remote-as 300
    network 192.168.50.0 mask 255.255.255.0
    neighbor 4.4.12.4 remote-as 200

R6)
    router bgp 300
    bgp router-id 6.6.6.6
    neighbor 5.5.12.5 remote-as 300
    network 192.168.60.0 mask 255.255.255.0
    neighbor 6.6.12.7 remote-as 400

R7)
    router bgp 400
    bgp router-id 7.7.7.7
    neighbor 7.7.12.8 remote-as 400
    network 192.168.70.0 mask 255.255.255.0
    neighbor 6.6.12.6 remote-as 300

R8)
    router bgp 400
    bgp router-id 8.8.8.8
    neighbor 7.7.12.7 remote-as 400
    network 192.168.80.0 mask 255.255.255.0





결과.



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ping도 다 가면 됨.

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Ex. 유형 2(같은 구역) + 유형 1(다른 구역)




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방법.



R1)
    router bgp 100
    bgp router-id 1.1.1.1
    neighbor 2.2.2.2 remote-as 100
    neighbor 2.2.2.2 update-source lo 0
    network 192.168.10.0 mask 255.255.255.0

R2)
    router bgp 100
    bgp router-id 2.2.2.2
    neighbor 1.1.1.1 remote-as 100
    neighbor 1.1.1.1 update-source lo 0
    neighbor 2.2.12.3 remote-as 200
    network 192.168.20.0 mask 255.255.255.0

R3)
    router bgp 200
    bgp router-id 3.3.3.3
    neighbor 4.4.4.4 remote-as 200
    neighbor 4.4.4.4 update-source lo 0
    neighbor 2.2.12.2 remote-as 100
    network 192.168.30.0 mask 255.255.255.0

R4)
    router bgp 200
    bgp router-id 4.4.4.4
    neighbor 4.4.12.5 remote-as 300
    neighbor 3.3.3.3 remote-as 200
    neighbor 3.3.3.3 update-source lo 0
    network 192.168.40.0 mask 255.255.255.0

R5)
    router bgp 300
    bgp router-id 5.5.5.5
    neighbor 4.4.12.4 remote-as 200
    neighbor 6.6.6.6 remote-as 300
    neighbor 6.6.6.6 update-source lo 0
    network 192.168.50.0 mask 255.255.255.0

R6)
    router bgp 300
    bgp router-id 6.6.6.6
    neighbor 6.6.12.7 remote-as 400
    neighbor 5.5.5.5 remote-as 300
    neighbor 5.5.5.5 update-source lo 0
    network 192.168.60.0 mask 255.255.255.0

R7)
    router bgp 400
    bgp router-id 7.7.7.7
    neighbor 6.6.12.6 remote-as 300
    neighbor 8.8.8.8 remote-as 400
    neighbor 8.8.8.8 update-source lo 0
    network 192.168.70.0 mask 255.255.255.0

R8)
    router bgp 400
    bgp router-id 8.8.8.8
    neighbor 7.7.7.7 remote-as 400
    neighbor 7.7.7.7 update-source lo 0
    network 192.168.80.0 mask 255.255.255.0





결과.



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Ex.


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  • loopback 간 neighbor를 맺으려고 하는 것임.
    -> ip route 전부 2개씩.
  • BGP에는 loopback만 들어가도록 할 것.

방법.


R1)
    ip route 192.168.20.0 255.255.255.0 1.1.12.2
    ip route 192.168.30.0 255.255.255.0 1.1.12.2

    router bgp 100
    bgp router-id 1.1.1.1
    neighbor 2.2.2.2 remote-as 100
    neighbor 2.2.2.2 update-source lo 0
    network 192.168.10.0 mask 255.255.255.0

R2)
    ip route 192.168.10.0 255.255.255.0 1.1.12.1
    ip route 192.168.30.0 255.255.255.0 2.2.12.3

    router bgp 100
    bgp router-id 2.2.2.2
    neighbor 1.1.1.1 remote-as 100
    neighbor 3.3.3.3 remote-as 200
    neighbor 1.1.1.1 update-source lo 0
    neighbor 3.3.3.3 update-source lo 0
    neighbor 3.3.3.3 ebgp-multihop 2
    network 192.168.20.0 mask 255.255.255.0

R3)
    ip rotue 192.168.20.0 255.255.255.0 2.2.12.2
    ip route 192.168.40.0 255.255.255.0 3.3.12.4

    router bgp 200
    bgp router-id 3.3.3.3
    neighbor 4.4.4.4 remote-as 200
    neighbor 2.2.2.2 remote-as 100
    neighbor 4.4.4.4 update-source lo 0
    neighbor 2.2.2.2 update-source lo 0
    neighbor 2.2.2.2 ebgp-multihop 2
    network 192.168.30.0 mask 255.255.255.0

R4)
    ip route 192.168.30.0 255.255.255.0 3.3.12.3
    ip route 192.168.20.0 255.255.255.0 3.3.12.3

    router bgp 200
    bgp router-id 200
    bgp router-id 4.4.4.4
    neighbor 3.3.3.3 remote-as 200
    neighbor 3.3.3.3 update-source lo o
    network 192.168.40.0 mask 255.255.255.0

※ 참고) neighbor [neighbor를 맺으려는 루프백 주소]




결과.



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