BGPテーブルとルーティングテーブルについて
設定
物理：192.168.xy.0/24
Loopback：x.x.x.x/24
AS200では10.1.1.0/24を広告
Before
iosv-3#sh ip bgp
BGP table version is 1, local router ID is 3.3.3.3
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
* i 10.1.1.0/24 192.168.102.10 0 100 0 200 i
* i 192.168.58.8 0 100 0 200 i
* i 192.168.16.6 0 100 0 200 i
iosv-3#sh ip ro | b Gate
Gateway of last resort is not set
1.0.0.0/32 is subnetted, 1 subnets
O 1.1.1.1 [110/2] via 192.168.13.1, 00:18:13, GigabitEthernet0/1
2.0.0.0/32 is subnetted, 1 subnets
O 2.2.2.2 [110/2] via 192.168.23.2, 00:17:33, GigabitEthernet0/2
3.0.0.0/32 is subnetted, 1 subnets
C 3.3.3.3 is directly connected, Loopback0
5.0.0.0/32 is subnetted, 1 subnets
O 5.5.5.5 [110/2] via 192.168.35.5, 00:14:28, GigabitEthernet0/0
7.0.0.0/32 is subnetted, 1 subnets
O 7.7.7.7 [110/2] via 192.168.37.7, 00:14:48, GigabitEthernet0/3
192.168.13.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.13.0/24 is directly connected, GigabitEthernet0/1
L 192.168.13.3/32 is directly connected, GigabitEthernet0/1
192.168.23.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.23.0/24 is directly connected, GigabitEthernet0/2
L 192.168.23.3/32 is directly connected, GigabitEthernet0/2
192.168.35.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.35.0/24 is directly connected, GigabitEthernet0/0
L 192.168.35.3/32 is directly connected, GigabitEthernet0/0
192.168.37.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.37.0/24 is directly connected, GigabitEthernet0/3
L 192.168.37.3/32 is directly connected, GigabitEthernet0/3BGPテーブルには10.1.1.0/24の経路が載っているのに、ルーティングテーブルには載っていない。
After
iosv-1(config)#router bgp 100
iosv-1(config-router)#nei 3.3.3.3 next-hop-self
iosv-5(config-router)#nei 3.3.3.3 next-hop-self
iosv-2(config-router)#nei 3.3.3.3 next-hop-selfネクストホップを書き換える。
iosv-3#sh ip bgp | b Origin
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 10.1.1.0/24 2.2.2.2 0 100 0 200 i
* i 5.5.5.5 0 100 0 200 i
*>i 1.1.1.1 0 100 0 200 i
iosv-3#sh ip ro | b Gate
Gateway of last resort is not set
1.0.0.0/32 is subnetted, 1 subnets
O 1.1.1.1 [110/2] via 192.168.13.1, 00:19:47, GigabitEthernet0/1
2.0.0.0/32 is subnetted, 1 subnets
O 2.2.2.2 [110/2] via 192.168.23.2, 00:19:07, GigabitEthernet0/2
3.0.0.0/32 is subnetted, 1 subnets
C 3.3.3.3 is directly connected, Loopback0
5.0.0.0/32 is subnetted, 1 subnets
O 5.5.5.5 [110/2] via 192.168.35.5, 00:16:02, GigabitEthernet0/0
7.0.0.0/32 is subnetted, 1 subnets
O 7.7.7.7 [110/2] via 192.168.37.7, 00:16:22, GigabitEthernet0/3
10.0.0.0/24 is subnetted, 1 subnets
B 10.1.1.0 [200/0] via 1.1.1.1, 00:00:37
192.168.13.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.13.0/24 is directly connected, GigabitEthernet0/1
L 192.168.13.3/32 is directly connected, GigabitEthernet0/1
192.168.23.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.23.0/24 is directly connected, GigabitEthernet0/2
L 192.168.23.3/32 is directly connected, GigabitEthernet0/2
192.168.35.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.35.0/24 is directly connected, GigabitEthernet0/0
L 192.168.35.3/32 is directly connected, GigabitEthernet0/0
192.168.37.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.37.0/24 is directly connected, GigabitEthernet0/3
L 192.168.37.3/32 is directly connected, GigabitEthernet0/3ルーティングテーブルにも10.1.1.0/24の経路が載った。
つまり、ルーティングテーブルに経路を載せるためには、ネクストホップを解決している必要がある。
見る人が見ればくっそ今更な話かもしれないけど全然知らなかった。