我通过 iBGP 从 R1 收到一条默认路由。在 R2 和 R3 上，我都配置了默认信息来源。在 R4 上，我只在 OSPF 数据库中看到一条默认路由；要么到 R2，要么到 R3。当我关闭从 R2/R3 到 R1 的一条链路时，我看到 OSPF 数据库中出现了另一条默认路由。
我的实际拓扑稍微复杂一些，那么是否有可能在 R4 上出现两个默认路由，而无需始终产生默认信息？我希望在 R2/R3 上通告的默认路由依赖于 RIB 中存在的 R1 默认路由。
谢谢
编辑：添加配置和输出
R1
set interfaces ge-0/0/0 unit 0 family inet address 10.0.1.1/30
set interfaces ge-0/0/1 unit 0 family inet address 10.0.1.5/30
set interfaces ge-0/0/2 unit 0 family inet address 10.1.1.1/30
set interfaces lo0 unit 0 family inet address 192.168.1.3/32
...
set routing-options static route 0.0.0.0/0 discard
set routing-options autonomous-system 65535
set protocols bgp group internal type internal
set protocols bgp group internal bfd-liveness-detection minimum-interval 300
set protocols bgp group internal bfd-liveness-detection multiplier 3
set protocols bgp group internal neighbor 10.0.1.2 export default-originate
set protocols bgp group internal neighbor 10.0.1.6 export default-originate
set protocols ospf export ospf-default
set protocols ospf area 0.0.0.0 interface ge-0/0/2.0
set protocols bfd traceoptions file bfd-trace
set protocols bfd traceoptions flag all
R2
redundancy
bfd-template single-hop BGP-BFD
interval min-tx 300 min-rx 300 multiplier 3
dampening 2 1000 3000 8
!
interface Loopback0
ip address 192.168.1.1 255.255.255.255
!
interface GigabitEthernet1
ip address 10.0.1.2 255.255.255.252
negotiation auto
bfd template BGP-BFD
!
interface GigabitEthernet2
ip address 10.0.1.9 255.255.255.252
negotiation auto
bfd template BGP-BFD
!
interface GigabitEthernet3
no ip address
negotiation auto
!
interface GigabitEthernet3.100
encapsulation dot1Q 100
ip address 10.0.1.13 255.255.255.252
!
interface GigabitEthernet3.300
encapsulation dot1Q 300
ip address 10.0.1.21 255.255.255.252
!
router ospf 110
network 10.0.1.9 0.0.0.0 area 0
network 10.0.1.13 0.0.0.0 area 0
network 10.0.1.21 0.0.0.0 area 0
network 192.168.1.1 0.0.0.0 area 0
default-information originate
!
router bgp 65535
bgp log-neighbor-changes
bgp redistribute-internal
redistribute ospf 110
neighbor 10.0.1.1 remote-as 65535
neighbor 10.0.1.1 fall-over bfd
neighbor 10.0.1.10 remote-as 65535
neighbor 10.0.1.10 fall-over bfd
!
R3
redundancy
bfd-template single-hop BGP-BFD
interval min-tx 300 min-rx 300 multiplier 3
dampening 2 1000 3000 8
!
interface Loopback0
ip address 192.168.1.2 255.255.255.255
!
interface GigabitEthernet1
ip address 10.0.1.6 255.255.255.252
negotiation auto
bfd template BGP-BFD
!
interface GigabitEthernet2
ip address 10.0.1.10 255.255.255.252
negotiation auto
bfd template BGP-BFD
!
interface GigabitEthernet3
no ip address
negotiation auto
!
interface GigabitEthernet3.200
encapsulation dot1Q 200
ip address 10.0.1.17 255.255.255.252
!
interface GigabitEthernet3.400
encapsulation dot1Q 400
ip address 10.0.1.25 255.255.255.252
!
router ospf 110
network 10.0.1.10 0.0.0.0 area 0
network 10.0.1.17 0.0.0.0 area 0
network 10.0.1.25 0.0.0.0 area 0
network 192.168.1.2 0.0.0.0 area 0
default-information originate
!
router bgp 65535
bgp log-neighbor-changes
bgp redistribute-internal
redistribute ospf 110
neighbor 10.0.1.5 remote-as 65535
neighbor 10.0.1.5 fall-over bfd
neighbor 10.0.1.9 remote-as 65535
neighbor 10.0.1.9 fall-over bfd
!
R4
interface Loopback0
ip address 192.168.1.4 255.255.255.255
!
interface GigabitEthernet1
no ip address
negotiation auto
!
interface GigabitEthernet1.100
encapsulation dot1Q 100
ip address 10.0.1.14 255.255.255.252
!
interface GigabitEthernet1.200
encapsulation dot1Q 200
ip address 10.0.1.18 255.255.255.252
!
interface GigabitEthernet2
no ip address
negotiation auto
!
interface GigabitEthernet3
ip address 172.16.0.1 255.255.0.0
negotiation auto
!
router ospf 110
network 10.0.1.14 0.0.0.0 area 0
network 10.0.1.18 0.0.0.0 area 0
network 172.16.0.1 0.0.0.0 area 0
network 192.168.1.4 0.0.0.0 area 0
!
R5
interface Loopback0
ip address 192.168.1.5 255.255.255.255
!
interface GigabitEthernet1
no ip address
negotiation auto
!
interface GigabitEthernet1.300
encapsulation dot1Q 300
ip address 10.0.1.22 255.255.255.252
!
interface GigabitEthernet1.400
encapsulation dot1Q 400
ip address 10.0.1.26 255.255.255.252
!
interface GigabitEthernet2
no ip address
shutdown
negotiation auto
!
interface GigabitEthernet3
no ip address
shutdown
negotiation auto
!
router ospf 110
network 10.0.1.22 0.0.0.0 area 0
network 10.0.1.26 0.0.0.0 area 0
network 192.168.1.5 0.0.0.0 area 0
!
R4-输出
R4# sho ip ospf database
OSPF Router with ID (192.168.1.4) (Process ID 110)
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count
192.168.1.1 192.168.1.1 1219 0x80000005 0x007AA3 4
192.168.1.2 192.168.1.2 1218 0x80000005 0x008881 4
192.168.1.4 192.168.1.4 1223 0x80000003 0x00B0D9 4
192.168.1.5 192.168.1.5 1219 0x80000003 0x0071C3 3
Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
10.0.1.10 192.168.1.2 1230 0x80000001 0x006F74
10.0.1.14 192.168.1.4 1223 0x80000001 0x004F8C
10.0.1.18 192.168.1.4 1223 0x80000001 0x0035A1
10.0.1.22 192.168.1.5 1219 0x80000001 0x0003CE
10.0.1.26 192.168.1.5 1219 0x80000001 0x00E8E3
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
0.0.0.0 192.168.1.2 1217 0x80000001 0x00CD0B 110
R5——输出
R5#sho ip ospf database
OSPF Router with ID (192.168.1.5) (Process ID 110)
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count
192.168.1.1 192.168.1.1 473 0x80000006 0x0078A4 4
192.168.1.2 192.168.1.2 503 0x80000006 0x008682 4
192.168.1.4 192.168.1.4 451 0x80000004 0x00AEDA 4
192.168.1.5 192.168.1.5 471 0x80000004 0x006FC4 3
Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
10.0.1.10 192.168.1.2 503 0x80000002 0x006D75
10.0.1.14 192.168.1.4 451 0x80000002 0x004D8D
10.0.1.18 192.168.1.4 451 0x80000002 0x0033A2
10.0.1.22 192.168.1.5 471 0x80000002 0x0001CF
10.0.1.26 192.168.1.5 471 0x80000002 0x00E6E4
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
0.0.0.0 192.168.1.2 503 0x80000002 0x00CB0C 110
R2 BGP/OSPF
BGP table version is 15, local router ID is 192.168.1.1
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
r>i 0.0.0.0 10.0.1.1 100 0 i
* i 10.0.1.8/30 10.0.1.10 0 100 0 ?
*> 0.0.0.0 0 32768 ?
* i 10.0.1.12/30 10.0.1.18 2 100 0 ?
*> 0.0.0.0 0 32768 ?
*> 10.0.1.16/30 10.0.1.14 2 32768 ?
* i 10.0.1.10 0 100 0 ?
* i 10.0.1.20/30 10.0.1.26 2 100 0 ?
*> 0.0.0.0 0 32768 ?
*> 10.0.1.24/30 10.0.1.22 2 32768 ?
* i 10.0.1.10 0 100 0 ?
* i 172.16.0.0 10.0.1.18 2 100 0 ?
*> 10.0.1.14 2 32768 ?
*> 192.168.1.1/32 0.0.0.0 0 32768 ?
Network Next Hop Metric LocPrf Weight Path
* i 192.168.1.2/32 10.0.1.10 0 100 0 ?
*> 10.0.1.10 2 32768 ?
* i 192.168.1.4/32 10.0.1.18 2 100 0 ?
*> 10.0.1.14 2 32768 ?
* i 192.168.1.5/32 10.0.1.26 2 100 0 ?
*> 10.0.1.22 2 32768 ?
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count
192.168.1.1 192.168.1.1 736 0x8000002D 0x002ACB 4
192.168.1.2 192.168.1.2 923 0x8000002D 0x0038A9 4
192.168.1.4 192.168.1.4 1263 0x8000002B 0x006002 4
192.168.1.5 192.168.1.5 912 0x8000002B 0x0021EB 3
Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
10.0.1.10 192.168.1.2 923 0x80000029 0x001F9C
10.0.1.14 192.168.1.4 1263 0x80000029 0x00FEB4
10.0.1.18 192.168.1.4 1263 0x80000029 0x00E4C9
10.0.1.22 192.168.1.5 912 0x80000029 0x00B2F6
10.0.1.26 192.168.1.5 912 0x80000029 0x00980C
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
0.0.0.0 192.168.1.2 178 0x80000001 0x00CD0B 110
R3 BGP/OSPF
BGP table version is 17, local router ID is 192.168.1.2
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
*>i 0.0.0.0 10.0.1.5 100 0 i
* i 10.0.1.8/30 10.0.1.9 0 100 0 ?
*> 0.0.0.0 0 32768 ?
*> 10.0.1.12/30 10.0.1.18 2 32768 ?
* i 10.0.1.9 0 100 0 ?
* i 10.0.1.16/30 10.0.1.14 2 100 0 ?
*> 0.0.0.0 0 32768 ?
*> 10.0.1.20/30 10.0.1.26 2 32768 ?
* i 10.0.1.9 0 100 0 ?
* i 10.0.1.24/30 10.0.1.22 2 100 0 ?
*> 0.0.0.0 0 32768 ?
* i 172.16.0.0 10.0.1.14 2 100 0 ?
*> 10.0.1.18 2 32768 ?
* i 192.168.1.1/32 10.0.1.9 0 100 0 ?
Network Next Hop Metric LocPrf Weight Path
*> 10.0.1.9 2 32768 ?
* i 192.168.1.2/32 10.0.1.9 2 100 0 ?
*> 0.0.0.0 0 32768 ?
* i 192.168.1.4/32 10.0.1.14 2 100 0 ?
*> 10.0.1.18 2 32768 ?
* i 192.168.1.5/32 10.0.1.22 2 100 0 ?
*> 10.0.1.26 2 32768 ?
OSPF Router with ID (192.168.1.2) (Process ID 110)
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count
192.168.1.1 192.168.1.1 944 0x8000002D 0x002ACB 4
192.168.1.2 192.168.1.2 1129 0x8000002D 0x0038A9 4
192.168.1.4 192.168.1.4 1470 0x8000002B 0x006002 4
192.168.1.5 192.168.1.5 1119 0x8000002B 0x0021EB 3
Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
10.0.1.10 192.168.1.2 1129 0x80000029 0x001F9C
10.0.1.14 192.168.1.4 1470 0x80000029 0x00FEB4
10.0.1.18 192.168.1.4 1470 0x80000029 0x00E4C9
10.0.1.22 192.168.1.5 1119 0x80000029 0x00B2F6
10.0.1.26 192.168.1.5 1119 0x80000029 0x00980C
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
0.0.0.0 192.168.1.2 384 0x80000001 0x00CD0B 110
答案1
似乎第一个将默认路由从 iBGP 重新分配到 OSPF 的路由器（R2/R3 之外）将是 OSPF 放入数据库的唯一默认路由。我注意到，无论哪个路由器尝试将默认路由重新分配到 OSPF，都会遇到 BGP RIB 故障，因为来自另一个路由器的默认路由已由 OSPF 安装到 RIB 中并指向另一个路由器。我读到，如果路由不在路由表中，则不会将来自 BGP 的路由重新分配到另一个协议中。