BGP 조건부 광고 기능

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업데이트:2020년 6월 15일

문서 ID:215634

편견 없는 언어

본 제품에 대한 문서 세트는 편견 없는 언어를 사용하기 위해 노력합니다. 본 설명서 세트의 목적상, 편견 없는 언어는 나이, 장애, 성별, 인종 정체성, 민족 정체성, 성적 지향성, 사회 경제적 지위 및 교차성에 기초한 차별을 의미하지 않는 언어로 정의됩니다. 제품 소프트웨어의 사용자 인터페이스에서 하드코딩된 언어, RFP 설명서에 기초한 언어 또는 참조된 서드파티 제품에서 사용하는 언어로 인해 설명서에 예외가 있을 수 있습니다. 시스코에서 어떤 방식으로 포용적인 언어를 사용하고 있는지 자세히 알아보세요.

이 번역에 관하여

Cisco는 전 세계 사용자에게 다양한 언어로 지원 콘텐츠를 제공하기 위해 기계 번역 기술과 수작업 번역을 병행하여 이 문서를 번역했습니다. 아무리 품질이 높은 기계 번역이라도 전문 번역가의 번역 결과물만큼 정확하지는 않습니다. Cisco Systems, Inc.는 이 같은 번역에 대해 어떠한 책임도 지지 않으며 항상 원본 영문 문서(링크 제공됨)를 참조할 것을 권장합니다.

소개

이 문서에서는 BGP 테이블에 다른 접두사가 있을 때 종속되는 경로 광고를 추가로 제어하는 BGP(Border Gateway Protocol) 조건부 광고 기능에 대해 설명합니다.

사전 요구 사항

요구 사항

Cisco에서는 이 주제에 대해 알고 있는 것이 좋습니다.

플랫폼 독립적

사용되는 구성 요소

이 문서의 정보는 다음 소프트웨어 및 하드웨어 버전을 기반으로 합니다.

IOS
IOS-XE
ASR1000

이 문서의 정보는 특정 랩 환경의 디바이스를 토대로 작성되었습니다.이 문서에 사용된 모든 디바이스는 초기화된(기본) 컨피그레이션으로 시작되었습니다.네트워크가 작동 중인 경우 모든 명령의 잠재적인 영향을 이해해야 합니다.

구성

R1, R2 및 R3을 구성합니다. 컨피그레이션은 여기에 지정됩니다.

네트워크 다이어그램

구성

R1 구성:

!
hostname R1
!
ip cef
!
interface Loopback0
ip address 1.1.1.1 255.255.255.255
! 
interface Loopback1
ip address 1.1.1.2 255.255.255.255
!
interface Loopback2
ip address 1.1.1.3 255.255.255.255
!
interface Loopback3
ip address 1.1.1.4 255.255.255.255
!
interface Loopback4
ip address 1.1.1.5 255.255.255.255
!
interface Loopback100
ip address 10.139.224.1 255.255.240.0
!
interface Ethernet0/0
ip address 10.10.12.1 255.255.255.0
!
router bgp 1
bgp log-neighbor-changes
neighbor 10.10.12.2 remote-as 2
!
address-family ipv4
network 0.0.0.0 route-map DEF
network 1.1.1.1 mask 255.255.255.255 route-map RM1
network 1.1.1.5 mask 255.255.255.255
redistribute connected route-map CUST
neighbor 10.10.12.2 activate
neighbor 10.10.12.2 send-community
neighbor 10.10.12.2 soft-reconfiguration inbound
exit-address-family
!
ip forward-protocol nd
! 
ip bgp-community new-format
ip route 0.0.0.0 0.0.0.0 Null0
!
ip prefix-list CUST seq 5 permit 10.139.224.0/20
!
ip prefix-list DEFAULT seq 5 permit 0.0.0.0/0
!
ip prefix-list PL1 seq 5 permit 1.1.1.1/32
!
route-map CUST permit 10
match ip address prefix-list CUST
set community 64671:501
!
route-map RM1 permit 10
match ip address prefix-list PL1
set community 64952:3008
!
route-map DEF permit 10
match ip address prefix-list DEFAULT
set community 64848:3011 65011:200 65013:200
!
end

R2 구성:

!
hostname R2
!
ip cef
!
interface Loopback0
 ip address 2.2.2.2 255.255.255.255
!         
interface Ethernet0/0
 ip address 10.10.12.2 255.255.255.0
!
interface Ethernet0/1
 ip address 10.10.23.2 255.255.255.0
!
router bgp 2
 bgp log-neighbor-changes
 neighbor 10.10.12.1 remote-as 1
 neighbor 10.10.23.3 remote-as 3
 !
 address-family ipv4
  neighbor 10.10.12.1 activate
  neighbor 10.10.12.1 soft-reconfiguration inbound
  neighbor 10.10.23.3 activate
  neighbor 10.10.23.3 send-community
  neighbor 10.10.23.3 advertise-map ADV-MAP exist-map EXIST-MAP <<< This statement changes in non-exist-map
  neighbor 10.10.23.3 soft-reconfiguration inbound
 exit-address-family
!
ip forward-protocol nd
!
ip bgp-community new-format
ip community-list standard DEFAULT-ROUTE permit 65013:200
ip community-list standard DC1-ROUTES permit 64952:3008
ip community-list standard DC2-ROUTES permit 64671:501
ip community-list standard DC3-ROUTES permit 64950:3009
ip community-list standard DEFAULT-ROUTE-DENY deny 65013:200
!
!
ip prefix-list DEFAULT seq 5 permit 1.1.1.5/32
ip prefix-list DEFAULT seq 10 permit 1.1.1.1/32
!
ip prefix-list EXIST seq 5 permit 10.10.10.10/32
!
ip prefix-list DEFAULT-ROUTE seq 5 permit 0.0.0.0/0
!
ip prefix-list DEFAULT-ROUTE-DENY seq 5 deny 0.0.0.0/0
!
ip prefix-list IP1 seq 5 permit 10.139.224.0/20
!
ip prefix-list T2 seq 5 permit 1.1.1.5/32
!
route-map ADV-MAP permit 10
 match ip address prefix-list IP1
!
route-map ADV-MAP permit 20
 match community DC1-ROUTES DC2-ROUTES DC3-ROUTES
!
route-map EXIST-MAP permit 10
 description Verify Default Route from MDC-SWG
 match ip address prefix-list DEFAULT-ROUTE IP1
 match community DEFAULT-ROUTE
!
!
end

R3 구성:

!
hostname R3
!
ip cef
!
interface Loopback0
 ip address 3.3.3.3 255.255.255.255
!
interface Ethernet0/1
 ip address 10.10.23.3 255.255.255.0
 shutdown
!
router bgp 3
 bgp log-neighbor-changes
 neighbor 10.10.23.2 remote-as 2
 !
 address-family ipv4
  neighbor 10.10.23.2 activate
  neighbor 10.10.23.2 send-community
  neighbor 10.10.23.2 soft-reconfiguration inbound
 exit-address-family
!         
ip forward-protocol nd
!
ip bgp-community new-format
!
!
end

다음을 확인합니다.

조건 1:

기본 경로가 BGP RIB에 없는 경우 R2는 특정 경로를 광고하지 않아야 합니다.
기본 경로가 BGP RIB에 있는 경우 R2는 모든 경로를 광고해야 합니다.

exist-map 사용

조건 2:

기본 경로가 BGP RIB에 없는 경우 R2는 모든 경로를 광고해야 합니다.
기본 경로가 BGP RIB에 있는 경우 R2는 특정 경로를 광고하지 않아야 합니다.

존재하지 않는 맵 사용

R1#show ip bgp 
BGP table version is 7, local router ID is 10.139.224.1
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
 *>  0.0.0.0          0.0.0.0                  0         32768 i
 *>  1.1.1.1/32       0.0.0.0                  0         32768 i
 *>  1.1.1.5/32       0.0.0.0                  0         32768 i
 *>  10.139.224.0/20  0.0.0.0                  0         32768 ?

R2#show ip bgp 
BGP table version is 11, local router ID is 2.2.2.2
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
 *>  0.0.0.0          10.10.12.1               0             0 1 i
 *>  1.1.1.1/32       10.10.12.1               0             0 1 i
 *>  1.1.1.5/32       10.10.12.1               0             0 1 i
 *>  10.139.224.0/20  10.10.12.1               0             0 1 ?
R2#show ip bgp 0.0.0.0
BGP routing table entry for 0.0.0.0/0, version 9
Paths: (1 available, best #1, table default)
  Advertised to update-groups:
     1         
  Refresh Epoch 1
  1, (received & used)
    10.10.12.1 from 10.10.12.1 (10.139.224.1)
      Origin IGP, metric 0, localpref 100, valid, external, best
      Community: 64848:3011 65011:200 65013:200
      rx pathid: 0, tx pathid: 0x0

R2#show ip bgp neighbors 10.10.23.3 advertised-routes 
BGP table version is 11, local router ID is 2.2.2.2
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
 *>  0.0.0.0          10.10.12.1               0             0 1 i
 *>  1.1.1.1/32       10.10.12.1               0             0 1 i
 *>  1.1.1.5/32       10.10.12.1               0             0 1 i
 *>  10.139.224.0/20  10.10.12.1               0             0 1 ?

Total number of prefixes 4

Condition1 Verification:
========================
If default route is not present in BGP RIB, R2 should not advertise certain routes.
If default route is present in BGP RIB, R2 should advertise all the routes.
Use exist-map

R2's BGP Configuration:
=======================
R2#show running-config | sec bgp
router bgp 2
bgp log-neighbor-changes
neighbor 10.10.12.1 remote-as 1
neighbor 10.10.23.3 remote-as 3
!
address-family ipv4
neighbor 10.10.12.1 activate
neighbor 10.10.12.1 soft-reconfiguration inbound
neighbor 10.10.23.3 activate
neighbor 10.10.23.3 send-community
neighbor 10.10.23.3 advertise-map ADV-MAP exist-map EXIST-MAP
neighbor 10.10.23.3 soft-reconfiguration inbound
exit-address-family
ip bgp-community new-format


When Default route is removed from R2's BGP RIB:
================================================
*Mar 6 09:07:08.833: BGP(0): 10.10.12.1 rcv UPDATE about 0.0.0.0/0 -- withdrawn
*Mar 6 09:07:08.833: BGP(0): no valid path for 0.0.0.0/0
*Mar 6 09:07:08.833: BGP: topo global:IPv4 Unicast:base Remove_fwdroute for 0.0.0.0/0
*Mar 6 09:07:08.833: BGP(0): (base) 10.10.23.3 send unreachable (format) 0.0.0.0/0
*Mar 6 09:07:21.280: BPG(0): Condition EXIST-MAP changes to Withdraw
*Mar 6 09:07:21.353: BGP(0): net 1.1.1.1/32 matches ADV MAP ADV-MAP: bump version to 13
*Mar 6 09:07:21.353: BGP(0): net 10.139.224.0/20 matches ADV MAP ADV-MAP: bump version to 14
*Mar 6 09:07:21.362: BGP(0): Revise route installing 1 of 1 routes for 1.1.1.1/32 -> 10.10.12.1(global) to main IP table
*Mar 6 09:07:21.362: BGP(0): Revise route installing 1 of 1 routes for 10.139.224.0/20 -> 10.10.12.1(global) to main IP table
*Mar 6 09:07:38.933: BGP(0): (base) 10.10.23.3 send unreachable (format) 1.1.1.1/32
*Mar 6 09:07:38.933: BGP(0): (base) 10.10.23.3 send unreachable (format) 10.139.224.0/20

R2#show ip bgp neighbors 10.10.23.3 advertised-routes 
BGP table version is 14, local router ID is 2.2.2.2
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
 *>  1.1.1.5/32       10.10.12.1               0             0 1 i

Total number of prefixes 1 


When Default route is added back into R2's BGP RIB: 
===================================================
*Mar  6 09:15:22.883: BGP(0): 10.10.12.1 rcvd UPDATE w/ attr: nexthop 10.10.12.1, origin i, metric 0, merged path 1, AS_PATH , community 64848:3011 65011:200 65013:200
*Mar  6 09:15:22.883: BGP(0): 10.10.12.1 rcvd 0.0.0.0/0
*Mar  6 09:15:22.883: BGP(0): Revise route installing 1 of 1 routes for 0.0.0.0/0 -> 10.10.12.1(global) to main IP table
*Mar  6 09:15:22.883: BGP(0): (base) 10.10.23.3 send UPDATE (format) 0.0.0.0/0, next 10.10.23.2, metric 0, path 1
*Mar  6 09:16:21.759: BPG(0): Condition EXIST-MAP changes to Advertise
*Mar  6 09:16:21.759: BGP(0): net 1.1.1.1/32 matches ADV MAP ADV-MAP: bump version to 16
*Mar  6 09:16:21.759: BGP(0): net 10.139.224.0/20 matches ADV MAP ADV-MAP: bump version to 17
*Mar  6 09:16:21.768: BGP(0): Revise route installing 1 of 1 routes for 1.1.1.1/32 -> 10.10.12.1(global) to main IP table
*Mar  6 09:16:21.769: BGP(0): Revise route installing 1 of 1 routes for 10.139.224.0/20 -> 10.10.12.1(global) to main IP table
*Mar  6 09:16:21.769: BGP(0): (base) 10.10.23.3 send UPDATE (format) 1.1.1.1/32, next 10.10.23.2, metric 0, path 1
*Mar  6 09:16:21.769: BGP(0): (base) 10.10.23.3 send UPDATE (format) 10.139.224.0/20, next 10.10.23.2, metric 0, path 1

R2#show ip bgp neighbors 10.10.23.3 advertised-routes 
BGP table version is 17, local router ID is 2.2.2.2
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
 *>  0.0.0.0          10.10.12.1               0             0 1 i
 *>  1.1.1.1/32       10.10.12.1               0             0 1 i
 *>  1.1.1.5/32       10.10.12.1               0             0 1 i
 *>  10.139.224.0/20  10.10.12.1               0             0 1 ?

Total number of prefixes 4

Condition2 Verification:
=========================
If default route is not present in BGP RIB, R2 should advertise all the routes.
If default route is present in BGP RIB, R2 should not advertise certain routes.
Use non-exist-map

R2's BGP Configuration:
=======================
R2#show running-config | sec bgp
router bgp 2
bgp log-neighbor-changes
neighbor 10.10.12.1 remote-as 1
neighbor 10.10.23.3 remote-as 3
!
address-family ipv4
neighbor 10.10.12.1 activate
neighbor 10.10.12.1 soft-reconfiguration inbound
neighbor 10.10.23.3 activate
neighbor 10.10.23.3 send-community
neighbor 10.10.23.3 advertise-map ADV-MAP non-exist-map EXIST-MAP
neighbor 10.10.23.3 soft-reconfiguration inbound
exit-address-family
ip bgp-community new-format


When Default route is removed from R2's BGP RIB:
================================================
*Mar  6 09:21:24.445: BGP(0): 10.10.12.1 rcv UPDATE about 0.0.0.0/0 -- withdrawn
*Mar  6 09:21:24.445: BGP(0): no valid path for 0.0.0.0/0
*Mar  6 09:21:24.445: BGP: topo global:IPv4 Unicast:base Remove_fwdroute for 0.0.0.0/0
*Mar  6 09:21:24.445: BGP(0): (base) 10.10.23.3 send unreachable (format) 0.0.0.0/0
*Mar  6 09:22:22.050: BPG(0): Condition EXIST-MAP changes to Advertise
*Mar  6 09:22:22.050: BGP(0): net 1.1.1.1/32 matches ADV MAP ADV-MAP: bump version to 21
*Mar  6 09:22:22.050: BGP(0): net 10.139.224.0/20 matches ADV MAP ADV-MAP: bump version to 22
*Mar  6 09:22:22.060: BGP(0): Revise route installing 1 of 1 routes for 1.1.1.1/32 -> 10.10.12.1(global) to main IP table
*Mar  6 09:22:22.060: BGP(0): Revise route installing 1 of 1 routes for 10.139.224.0/20 -> 10.10.12.1(global) to main IP table
*Mar  6 09:22:22.060: BGP(0): (base) 10.10.23.3 send UPDATE (format) 1.1.1.1/32, next 10.10.23.2, metric 0, path 1
*Mar  6 09:22:22.060: BGP(0): (base) 10.10.23.3 send UPDATE (format) 10.139.224.0/20, next 10.10.23.2, metric 0, path 1

R2#show ip bgp neighbors 10.10.23.3 advertised-routes 
BGP table version is 22, local router ID is 2.2.2.2
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
 *>  1.1.1.1/32       10.10.12.1               0             0 1 i
 *>  1.1.1.5/32       10.10.12.1               0             0 1 i
 *>  10.139.224.0/20  10.10.12.1               0             0 1 ?

Total number of prefixes 3 


When Default route is added back into R2's BGP RIB:
=====================================================
*Mar  6 09:23:04.461: BGP(0): 10.10.12.1 rcvd UPDATE w/ attr: nexthop 10.10.12.1, origin i, metric 0, merged path 1, AS_PATH , community 64848:3011 65011:200 65013:200
*Mar  6 09:23:04.461: BGP(0): 10.10.12.1 rcvd 0.0.0.0/0
*Mar  6 09:23:04.461: BGP(0): Revise route installing 1 of 1 routes for 0.0.0.0/0 -> 10.10.12.1(global) to main IP table
*Mar  6 09:23:04.461: BGP(0): (base) 10.10.23.3 send UPDATE (format) 0.0.0.0/0, next 10.10.23.2, metric 0, path 1
*Mar  6 09:23:22.090: BPG(0): Condition EXIST-MAP changes to Withdraw
*Mar  6 09:23:22.090: BGP(0): net 1.1.1.1/32 matches ADV MAP ADV-MAP: bump version to 24
*Mar  6 09:23:22.090: BGP(0): net 10.139.224.0/20 matches ADV MAP ADV-MAP: bump version to 25
*Mar  6 09:23:22.103: BGP(0): Revise route installing 1 of 1 routes for 1.1.1.1/32 -> 10.10.12.1(global) to main IP table
*Mar  6 09:23:22.103: BGP(0): Revise route installing 1 of 1 routes for 10.139.224.0/20 -> 10.10.12.1(global) to main IP table
*Mar  6 09:23:35.248: BGP(0): (base) 10.10.23.3 send unreachable (format) 1.1.1.1/32
*Mar  6 09:23:35.248: BGP(0): (base) 10.10.23.3 send unreachable (format) 10.139.224.0/20

R2#show ip bgp neighbors 10.10.23.3 advertised-routes 
BGP table version is 25, local router ID is 2.2.2.2
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
 *>  0.0.0.0          10.10.12.1               0             0 1 i
 *>  1.1.1.5/32       10.10.12.1               0             0 1 i

Total number of prefixes 2

	Exist-map 상태	Advertise-map 상태
기본 경로가 있는 경우	조건 일치	광고
기본 경로가 없는 경우	조건이 일치하지 않음	철회됨

	존재하지 않는 맵 상태	Advertise-map 상태
기본 경로가 있는 경우	조건 일치	철회
기본 경로가 없는 경우	조건이 일치하지 않음	광고

문제 해결

중요한 명령은 BGP 조건부 맵과 연결된 경로 맵의 백엔드 이동을 제공하는 debug ip bgp 업데이트입니다.대규모 네트워크에서 ACL을 사용하여 조건부 디버그를 실행합니다.

참고:BGP Scanner 프로세스는 60초마다 실행되므로 exist-map/non-exist-map에 대한 업데이트를 가져오는 즉시 Advertise-map이 트리거되는 데 60초가 걸립니다.

Cisco 엔지니어가 작성

Jaivik Shah
Cisco TAC 엔지니어

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