了解OSPF路由重分发到BGP

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已更新: 2026 年 9 月 8 日
文档 ID:5242

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简介

本文档介绍思科路由器上开放最短路径优先 (OSPF) 到边界网关协议 (BGP) 的重分发行为。

先决条件

要求

Cisco建议您先了解OSPF路由类型、BGP基础知识和路由重分布，然后再使用本文档。

使用的组件

本文档不限于特定的软件和硬件版本。

note-icon

注意：本文档中的示例使用Cisco IOS软件命令语法。

本文档中的信息都是基于特定实验室环境中的设备编写的。本文档中使用的所有设备最初均采用原始（默认）配置。如果您的网络处于活动状态，请确保您了解所有命令的潜在影响。

背景信息

本技术说明解释了Cisco路由器上OSPF到BGP重分发的行为。RFC 1403记录了有关OSPF和BGP之间交互的历史指南。

有几种类型的 OSPF 路由：

  • 区域内路由 — 在多区域OSPF网络中，同一区域内的路由器将源自某一区域的路由视为区域内路由。这些路由在show ip route命令输出中标记为O。

  • 域间——当路由穿过OSPF局域边界路由器(ABR)时，路由一般被称为OSPF区域间路由。在 show ip route 命令输出中，这些路由标记为 O IA。

    区域内路由和区域间路由也称为OSPF内部路由，因为它们代表源自OSPF域中的前缀，而不是重分发到OSPF的路由。

  • External Type-2或External Type-1 — 重分发到OSPF中的路由（例如Connected、Static或其他路由协议）称为External Type-2或External Type-1。在show ip route命令输出中，这些路由标记为O E2或O E1。

  • NSSA External Type-2或NSSA External Type 1 — 将某个区域配置为次末节区域(NSSA)并将路由重分发到OSPF时，这些路由称为NSSA External Type-2或NSSA External Type-1。在show ip route命令输出中，这些路由标记为O N2或O N1。

关于外部 2 类或 1 类和 NSSA 2 类或 1 类之间的区别不在本文档讨论范围内。有关详细信息，请参阅《OSPF 设计指南》。

默认行为是不将任何路由从 OSPF 重分配到 BGP 中。必须配置重分配。您可以使用route-map命令在OSPF到BGP重分发期间过滤路由。要明确选择路由类型，请使用适用的match internal、match external或match nssa-external选项。如果没有匹配选项，则默认情况下redistribute ospf会重分发OSPF内部路由。

网络设置

本文档讨论五个主要的OSPF到BGP重分发案例。拓扑A适用于前四个情况。拓扑B适用于“将OSPF NSSA外部路由重分配到BGP”部分中描述的NSSA外部路由案例。


Redistribution OSPF to BGP Topology A将 OSPF 重新分发到 BGP 拓扑 A

仅将OSPF内部（区域内和区域间）路由重分发到BGP

如果配置了将 OSPF 重新分发到不带关键字的 BGP 中，则默认情况下，仅 OSPF 区域内和区域间路由会重新分发到 BGP 中。要重分布OSPF Intra-area和Inter-area路由，可以在router bgp下将internal关键字与redistribute命令一起使用。

此路由器B(RTB)配置将OSPF内部前缀10.2.2.0/24、10.108.1.0/24和10.108.2.0/24重分发到BGP:

RTB 
hostname RTB
!
interface GigabitEthernet0/0
 ip address 10.3.3.1 255.255.255.0
 duplex auto
 speed auto
 media-type rj45
!
interface GigabitEthernet0/1
 ip address 10.2.2.3 255.255.255.0
 duplex auto
 speed auto
 media-type rj45  
! 
router ospf 1
 network 10.2.2.0 0.0.0.255 area 1  
! 
router bgp 100 
redistribute ospf 1 

!-- This redistributes only OSPF intra-area and inter-area routes into BGP.  

neighbor 10.3.3.2 remote-as 200 
! 
end 

RTB#show ip route
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

      10.0.0.0/8 is variably subnetted, 6 subnets, 2 masks
C 10.2.2.0/24 is directly connected, GigabitEthernet0/1
L        10.2.2.3/32 is directly connected, GigabitEthernet0/1
C        10.3.3.0/24 is directly connected, GigabitEthernet0/0
L        10.3.3.1/32 is directly connected, GigabitEthernet0/0
O IA 10.108.1.0/24 [110/3] via 10.2.2.2, 00:08:38, GigabitEthernet0/1 O 10.108.2.0/24 [110/2] via 10.2.2.2, 00:39:13, GigabitEthernet0/1
O E2  192.168.1.0/24 [110/20] via 10.2.2.2, 00:07:39, GigabitEthernet0/1
O E1  192.168.2.0/24 [110/23] via 10.2.2.2, 00:07:38, GigabitEthernet0/1
RTB# 

路由器 B 只会重分配 OSPF 内部路由：

RTB#show ip bgp
BGP table version is 12, local router ID is 10.3.3.1
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, 
              t secondary path, 
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

     Network          Next Hop            Metric LocPrf Weight Path
 *> 10.2.2.0/24 0.0.0.0 0 32768 ? *> 10.108.1.0/24 10.2.2.2 3 32768 ? *> 10.108.2.0/24 10.2.2.2 2 32768 ?
RTB# 

路由器 C 从 BGP 获知以下路由：

RTC#show ip route
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

      10.0.0.0/8 is variably subnetted, 5 subnets, 2 masks
B 10.2.2.0/24 [20/0] via 10.3.3.1, 00:07:07
C        10.3.3.0/24 is directly connected, GigabitEthernet0/0
L        10.3.3.2/32 is directly connected, GigabitEthernet0/0
B 10.108.1.0/24 [20/3] via 10.3.3.1, 00:07:07 B 10.108.2.0/24 [20/2] via 10.3.3.1, 00:07:07
RTC#
RTC#show ip bgp
BGP table version is 8, local router ID is 10.3.3.2
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, 
              t secondary path, 
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

     Network          Next Hop            Metric LocPrf Weight Path
 *> 10.2.2.0/24 10.3.3.1 0 0 100 ? *> 10.108.1.0/24 10.3.3.1 3 0 100 ? *> 10.108.2.0/24 10.3.3.1 2 0 100 ?
RTC# 

仅将OSPF外部（类型1和2）路由重分发到BGP

要将OSPF外部路由重分布到BGP，请在router bgp下将external关键字与redistribute命令一起使用。使用 external 关键字时有三种选择：

  • 重新分发外部 1 类和 2 类（默认）

  • 重新分发外部 1 类

  • 重新分发外部 2 类


在配置模式下输入命令，如下所示：

RTB(config)#router bgp 100
RTB(config-router)#redistribute ospf 1 match external

此路由器B配置仅重分发OSPF外部路由，包括类型1和类型2路由：

RTB 
hostname RTB
!
interface GigabitEthernet0/0
 ip address 10.3.3.1 255.255.255.0
 duplex auto
 speed auto
 media-type rj45
!
interface GigabitEthernet0/1
 ip address 10.2.2.3 255.255.255.0
 duplex auto
 speed auto
 media-type rj45  
! 
router ospf 1
 network 10.2.2.0 0.0.0.255 area 1  
! 
router bgp 100   
 redistribute ospf 1 match external 1 external 2 

!--- This redistributes ONLY OSPF External routes, but both type-1 and type-2.  

neighbor 10.3.3.2 remote-as 200 
! 
end

注意：配置显示输入的命令是redistribute ospf 1 match external。这是正常的，因为OSPF会自动在配置中附加外部1 external 2。它同时匹配OSPF外部1和外部2路由，并且将两个路由重新分配到BGP中。

路由器 B 仅重新分发 OSPF 外部路由：

RTB#show ip bgp
BGP table version is 25, local router ID is 10.3.3.1
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, 
              t secondary path, 
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

     Network          Next Hop            Metric LocPrf Weight Path
 *>   192.168.1.0      10.2.2.2                20         32768 ?
 *>   192.168.2.0      10.2.2.2                23         32768 ?
RTB# 

路由器 C 从 BGP 了解这两个 OSPF 外部路由：

RTC#show ip route
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

      10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C        10.3.3.0/24 is directly connected, GigabitEthernet0/0
L        10.3.3.2/32 is directly connected, GigabitEthernet0/0
B 192.168.1.0/24 [20/20] via 10.3.3.1, 00:02:16 B 192.168.2.0/24 [20/23] via 10.3.3.1, 00:02:16

RTC#show ip bgp
BGP table version is 21, local router ID is 10.3.3.2
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, 
              t secondary path, 
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

     Network          Next Hop            Metric LocPrf Weight Path
 *> 192.168.1.0 10.3.3.1 20 0 100 ? *> 192.168.2.0 10.3.3.1 23 0 100 ?
RTC# 

仅将OSPF外部第1类或第2类路由重分发到BGP

要仅重分布第1类OSPF外部路由，请在路由器B的router bgp 100下输入以下命令：

RTB(config)#router bgp 100 
RTB(config-router)#redistribute ospf 1 match external 1

使用之前的配置，路由器B(RTB)BGP表显示路由器B仅将外部类型1路由重分发到BGP，而所有其他OSPF路由未重分发到BGP:

RTB#show ip bgp
BGP table version is 28, local router ID is 10.3.3.1
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, 
              t secondary path, 
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

     Network          Next Hop            Metric LocPrf Weight Path
 *>   192.168.2.0      10.2.2.2                23         32768 ?
RTB# 

要仅重分布第2类OSPF外部路由，请在路由器B的router bgp 100下输入以下命令：

RTB(config)#router bgp 100 
RTB(config-router)#redistribute ospf 1 match external 2

将OSPF内部和外部路由重分发到BGP

在这种情况下，OSPF内部路由以及OSPF第1类和第2类外部路由使用内部和外部匹配选项重新分发到BGP，如以下路由器B配置所示：

RTB 
hostname RTB
!
interface GigabitEthernet0/0
 ip address 10.3.3.1 255.255.255.0
 duplex auto
 speed auto
 media-type rj45
!
interface GigabitEthernet0/1
 ip address 10.2.2.3 255.255.255.0
 duplex auto
 speed auto
 media-type rj45  
! 
router ospf 1
 network 10.2.2.0 0.0.0.255 area 1  
! 
router bgp 100
 redistribute ospf 1 match internal external 1 external 2 

!--- This redistributes OSPF internal and external type 1 & 2 routes into BGP.  

neighbor 10.3.3.2 remote-as 200 
! 
end


同样，配置中的 external 替换为 external 1 external 2 。这是正常的，只有您指定希望重新分配到BGP的那些特定外部路由时除外。更改配置后，路由器B重新分发选定的内部和外部路由，而路由器C通过BGP获取这些路由：

RTB#show ip bgp
BGP table version is 6, local router ID is 10.3.3.1
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, 
              t secondary path, 
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

     Network          Next Hop            Metric LocPrf Weight Path
 *> 10.2.2.0/24 0.0.0.0 0 32768 ? *> 10.108.1.0/24 10.2.2.2 3 32768 ? *> 10.108.2.0/24 10.2.2.2 2 32768 ? *> 192.168.1.0 10.2.2.2 20 32768 ? *> 192.168.2.0 10.2.2.2 23 32768 ?
RTB#  RTC#show ip route
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

      10.0.0.0/8 is variably subnetted, 5 subnets, 2 masks
B 10.2.2.0/24 [20/0] via 10.3.3.1, 00:03:27
C        10.3.3.0/24 is directly connected, GigabitEthernet0/0
L        10.3.3.2/32 is directly connected, GigabitEthernet0/0
B 10.108.1.0/24 [20/3] via 10.3.3.1, 00:03:27 B 10.108.2.0/24 [20/2] via 10.3.3.1, 00:03:27 B 192.168.1.0/24 [20/20] via 10.3.3.1, 00:03:27 B 192.168.2.0/24 [20/23] via 10.3.3.1, 00:03:27
RTC# 

将OSPF NSSA外部路由重分发到BGP

这是一种特殊情况，只会将 NSSA 路由重新分发到 BGP 中。此案例与仅重分发到BGP的OSPF外部（类型1和2）路由部分中描述的情况非常相似。唯一的区别是，OSPF 现在会匹配 NSSA 外部路由，而不仅仅是外部路由。路由器 B 的路由表显示了这些 OSPF NSSA 外部路由：

RTB#show ip route
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

      10.0.0.0/8 is variably subnetted, 6 subnets, 2 masks
C        10.2.2.0/24 is directly connected, GigabitEthernet0/1
L        10.2.2.3/32 is directly connected, GigabitEthernet0/1
C        10.3.3.0/24 is directly connected, GigabitEthernet0/0
L        10.3.3.1/32 is directly connected, GigabitEthernet0/0
O IA 10.108.1.0/24 [110/3] via 10.2.2.2, 00:05:00, GigabitEthernet0/1 O 10.108.2.0/24 [110/2] via 10.2.2.2, 00:05:00, GigabitEthernet0/1 O N2 192.168.1.0/24 [110/20] via 10.2.2.1, 00:10:14, GigabitEthernet0/1 O N1 192.168.2.0/24 [110/22] via 10.2.2.2, 00:03:43, GigabitEthernet0/1
RTB# 

此网络图用于此案例：

Redistribution OSPF to BGP Topology B将 OSPF 重新分发到 BGP 拓扑 B

网络图显示路由器 B 同时接收 OSPF N1 和 N2 路由。如果仅使用nssa-external关键字，则默认行为是重新分配N1和N2路由。此配置允许RTB将OSPF N2(192.168.1.0/24)和OSPF N1(192.168.2.0/24)路由重分发到BGP:

RTB 
hostname RTB
!
interface GigabitEthernet0/0
 ip address 10.3.3.1 255.255.255.0
 duplex auto
 speed auto
 media-type rj45
!
interface GigabitEthernet0/1
 ip address 10.2.2.3 255.255.255.0
 duplex auto
 speed auto
 media-type rj45  
! 
router ospf 1
 area 1 nssa  network 10.2.2.0 0.0.0.255 area 1  
! 
router bgp 100 
 redistribute ospf 1 match nssa-external 1 nssa-external 2

!--- This redistributes only OSPF NSSA-external routes Type-1 and Type-2 into BGP.

 neighbor 10.3.3.2 remote-as 200
!
end 

注意：与OSPF外部配置类似，先前的配置显示match nssa-external 1 nssa-external 2，并且输入的命令为redistribute ospf 1 match nssa-external。这是正常现象，因为OSPF会在配置中自动附加nssa-external 1 nssa-external 2。它匹配OSPF N1和OSPF N2路由，并且把这两个路由重新分配到BGP。

在路由器 B 上进行配置更改后，它会重新分发 OSPF NSSA 外部路由，路由器 C 会从 BGP 获知 OSPF NSSA 外部路由：

RTB#show ip route
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

      10.0.0.0/8 is variably subnetted, 6 subnets, 2 masks
C        10.2.2.0/24 is directly connected, GigabitEthernet0/1
L        10.2.2.3/32 is directly connected, GigabitEthernet0/1
C        10.3.3.0/24 is directly connected, GigabitEthernet0/0
L        10.3.3.1/32 is directly connected, GigabitEthernet0/0
O IA     10.108.1.0/24 [110/3] via 10.2.2.2, 00:09:40, GigabitEthernet0/1
O        10.108.2.0/24 [110/2] via 10.2.2.2, 00:09:40, GigabitEthernet0/1
O N2 192.168.1.0/24 [110/20] via 10.2.2.1, 00:14:54, GigabitEthernet0/1 O N1 192.168.2.0/24 [110/22] via 10.2.2.2, 00:08:23, GigabitEthernet0/1
RTB#
RTB#show ip bgp
BGP table version is 17, local router ID is 10.3.3.1
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, 
              t secondary path, 
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

     Network          Next Hop            Metric LocPrf Weight Path
 *> 192.168.1.0 10.2.2.1 20 32768 ? *> 192.168.2.0 10.2.2.2 22 32768 ?
RTB#  RTC#show ip route
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

      10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C        10.3.3.0/24 is directly connected, GigabitEthernet0/0
L        10.3.3.2/32 is directly connected, GigabitEthernet0/0
B 192.168.1.0/24 [20/20] via 10.3.3.1, 00:01:29 B 192.168.2.0/24 [20/22] via 10.3.3.1, 00:01:29
RTC# 
RTC#show ip bgp
BGP table version is 41, local router ID is 10.3.3.2
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, 
              t secondary path, 
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

     Network          Next Hop            Metric LocPrf Weight Path
 *> 192.168.1.0 10.3.3.1 20 0 100 ? *> 192.168.2.0 10.3.3.1 22 0 100 ?
RTC# 

与 OSPF 外部路由相同，要仅重新分发 OSPF N1 路由，请在路由器 B 上的路由器 BGP 100 下输入以下命令：

RTB(config)#router bgp 100 
RTB(config-router)#redistribute ospf 1 match nssa-external 1 

!--- This redistributes only OSPF NSSA-external Type-1 routes into BGP.

要仅重分布OSPF N2路由，请在路由器B的router bgp 100下输入以下命令：

RTB(config)#router bgp 100  
RTB(config-router)#redistribute ospf 1 match nssa-external 2 

!--- This redistributes only OSPF NSSA-external Type-2 routes into BGP.

注意：也可以使用路由映射将OSPF第1类或第2类路由重分发到BGP。 

修改 OSPF 中的重分配选项

请务必了解连续的配置更改会给配置带来哪些改变。带有 match 选项的新命令不会覆盖之前的命令，而是会添加到之前的命令中。下一个示例说明配置命令序列如何影响重新分发：

R4#configure terminal
R4(config)#router bgp 100
R4(config-router)#redistribute ospf 1 match internal
R4(config-router)#^Z

!--- Initially, you redistribute internal OSPF routes into BGP 100.

R4#show run | include redistribute ospf
 redistribute ospf 1 match internal
R4#configure terminal
R4(config)#router bgp 100
R4(config-router)#redistribute ospf 1 match external
R4(config-router)#^Z

!--- With this second command, you tell BGP to also redistribute external OSPF routes.

R4#show run | include redistribute ospf
 redistribute ospf 1 match internal external 1 external 2
R4#
R4#configure terminal
R4(config)#router bgp 100
R4(config-router)#no redistribute ospf 1 match external 2
R4(config-router)#^Z

!--- With this no command, you only disable the redistribution of external type 2 into BGP. 
!--- All other types of routes previously configured remain.

R4#show run | include redistribute ospf
 redistribute ospf 1 match internal external 1
 
!--- As you can see, internal and external type 1 remain.

R4#configure terminal
R4(config)#router bgp 100
R4(config-router)#no redistribute ospf 1 match internal external 1
R4(config-router)#^Z 

!--- This no command removes all explicit match options but does not disable redistribution 
!--- The remaining redistribute ospf 1 command uses the default behavior and redistributes 
!--- internal routes only.

R4#show run | include redistribute ospf
 redistribute ospf 1
R4#configure terminal
R4(config)#router bgp 100
R4(config-router)#no redistribute ospf 1 

!--- Use no redistribute ospf  command in order to disable OSPF-to-BGP redistribution completely.

R4(config-router)# ^Z
R4#show run | include redistribute ospf
R4#


无法将iBGP获知的路由重分发到IGP

路由重分布将通过一种协议获知的路由传播到另一种路由协议。将BGP重分发到IGP中时，默认情况下仅重分发eBGP获知的路由。路由器上已知的iBGP获知的路由不会引入IGP中，以防止创建路由环路。

默认情况下，已禁用将 iBGP 重新分发到 IGP 中。运行bgp redistribute-internal命令以启用iBGP路由到IGP的重分发。需要采取预防措施以便将使用路由映射的特定路由重新分发到 IGP 中。

将 iBGP 路由重新分发到 OSPF 中的示例配置如下所示：

Router(config)#router bgp 65345 
Router(config-router)#bgp redistribute-internal
!
Router(config)#router ospf 100
Router(config-router)#redistribute bgp 65345 subnets
caution-icon

警告：将iBGP获知的路由重分配到IGP中会在自治系统内创建路由环路。仅使用路由映射重新分发明确批准的前缀。

将 OSPF 默认路由重新分发到 BGP 中

要将OSPF获取的默认路由重分发到BGP，请在路由映射中仅允许0.0.0.0/0，将路由映射应用到OSPF重分发，并启用使用default-information originate重分发默认路由：

!
route-map map_default_only permit 10
 match ip address acl_default_only
!
ip access-list standard acl_default_only
 permit 0.0.0.0
!
router bgp 64601
 redistribute ospf 1 route-map map_default_only
 default-information originate
!

!--- Distributes the default route in bgp

network 0.0.0.0命令是单独的发起方法，需要在路由表中提供准确的默认路由： 

!
router bgp 64601
 network 0.0.0.0
!

配置后，使用show ip bgp 0.0.0.0检验默认路由，并使用show ip bgp neighbors <neighbor-address> advertised-routes检验其通告。

note-icon

注意：BGP通常不重置会话就通告新路由。要请求即时、无中断的更新交换，请运行clear ip bgp * soft命令。此命令用于保持BGP会话的建立。

相关信息

修订历史记录

版本 发布日期 备注
3.0
08-Sep-2026
重新认证 — 更新的SEO和格式
2.0
22-Apr-2025
标题、标题和格式。
1.0
11-Oct-2001
初始版本
TAC Authored

由思科工程师提供

  • 胡利奥·希门尼斯
    思科项目经理

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