R1# show ip ospf rib
OSPF Router with ID (10.0.0.3) (Process ID 65001)
Base Topology (MTID 0)
OSPF local RIB
Codes: * - Best, > - Installed in global RIB
* 10.0.0.1/32, Intra, cost 10, area 0.0.0.0, Connected
via 10.0.0.1, Loopback1
* 10.0.0.2/32, Intra, cost 10, area 0.0.0.0, Connected
via 10.0.0.2, Loopback2
* 10.0.0.3/32, Intra, cost 10, area 0.0.0.0, Connected
via 10.0.0.3, Loopback3
* 10.0.0.4/32, Intra, cost 10, area 0.0.0.0, Connected
via 10.0.0.4, Loopback4
* 10.0.0.5/32, Intra, cost 10, area 0.0.0.0, Connected
via 10.0.0.5, Loopback5
* 10.0.12.0/24, Intra, cost 1, area 0.0.0.0, Connected
via 10.0.12.1, GigabitEthernet0/1
R2# show ip ospf rib
OSPF Router with ID (10.0.23.2) (Process ID 65001)
Base Topology (MTID 0)
OSPF local RIB
Codes: * - Best, > - Installed in global RIB
*> 10.0.0.1/32, Intra, cost 210, area 0.0.0.0
via 10.0.12.1, GigabitEthernet0/1
*> 10.0.0.2/32, Intra, cost 210, area 0.0.0.0
via 10.0.12.1, GigabitEthernet0/1
*> 10.0.0.3/32, Intra, cost 210, area 0.0.0.0
via 10.0.12.1, GigabitEthernet0/1
*> 10.0.0.4/32, Intra, cost 210, area 0.0.0.0
via 10.0.12.1, GigabitEthernet0/1
*> 10.0.0.5/32, Intra, cost 210, area 0.0.0.0
via 10.0.12.1, GigabitEthernet0/1
* 10.0.12.0/24, Intra, cost 200, area 0.0.0.0, Connected
via 10.0.12.2, GigabitEthernet0/1
R2# show ip route ospf
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, 9 subnets, 2 masks
O 10.0.0.1/32 [110/210] via 10.0.12.1, 00:12:15, GigabitEthernet0/1
O 10.0.0.2/32 [110/210] via 10.0.12.1, 00:12:15, GigabitEthernet0/1
O 10.0.0.3/32 [110/210] via 10.0.12.1, 00:12:15, GigabitEthernet0/1
O 10.0.0.4/32 [110/210] via 10.0.12.1, 00:12:15, GigabitEthernet0/1
O 10.0.0.5/32 [110/210] via 10.0.12.1, 00:06:49, GigabitEthernet0/1
R2# show ip bgp
BGP table version is 25, local router ID is 10.0.23.2
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
*> 10.0.0.1/32 10.0.12.1 210 32768 ?
*> 10.0.0.2/32 10.0.12.1 210 32768 ?
*> 10.0.0.3/32 10.0.12.1 210 32768 ?
*> 10.0.0.4/32 10.0.12.1 210 32768 ?
*> 10.0.0.5/32 10.0.12.1 210 32768 ?
*> 10.0.12.0/24 0.0.0.0 0 32768 ?
R2# show ip bgp neighbors 10.0.23.3 advertised-routes
BGP table version is 25, local router ID is 10.0.23.2
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
*> 10.0.0.1/32 10.0.12.1 210 32768 ?
*> 10.0.0.2/32 10.0.12.1 210 32768 ?
*> 10.0.0.3/32 10.0.12.1 210 32768 ?
*> 10.0.0.4/32 10.0.12.1 210 32768 ?
*> 10.0.0.5/32 10.0.12.1 210 32768 ?
*> 10.0.12.0/24 0.0.0.0 0 32768 ?
Total number of prefixes 6
R3# show ip bgp
BGP table version is 12, local router ID is 10.0.23.3
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,
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found
Network Next Hop Metric LocPrf Weight Path
*> 10.0.0.1/32 10.0.23.2 210 0 65001 ?
*> 10.0.0.2/32 10.0.23.2 0 0 65001 ?
*> 10.0.0.3/32 10.0.23.2 3000 0 65001 ?
*> 10.0.0.4/32 10.0.23.2 43000 0 65001 ?
*> 10.0.0.5/32 10.0.23.2 3000 0 65001 ?
*> 10.0.12.0/24 10.0.23.2 3000 0 65001 ?
表にまとめると以下の通りです。一部、属性が意図通りに受信出来ていません…
経路
意図した MED 値
実際の MED 値
意図した結果になったか?
10.0.0.1/32
無し
210
X
10.0.0.2/32
0
210
○
10.0.0.3/32
3,210
3,000
X
10.0.0.4/32
43,000
43,000
○
10.0.0.5/32
3,000
3,000
○
問題点は以下の 2 点です。
10.0.0.1/32 の MED が「missing」では無く、「210」になっている (※ これを「意図しない」というのはおかしく、R2 のコンフィグで記載した通り、そもそも MED を除去する意図の route-map が書けていないので、想定通りと言えば想定通り…)
10.0.0.3/32 が R2 からの広告時に MED を「+3,000」しているにも関わらず、R3 で受信後の MED 値は「3,000」になっている (「加算」では無く、「上書き」になっている。但し、R3 の受信側で設定している「+40,000」は効いている…)
最終的なルーティングテーブルは以下となりました。
1 2 3 4 5 6 7 8 91011121314151617181920
R3# show ip route bgp
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, 8 subnets, 2 masks
B 10.0.0.1/32 [20/210] via 10.0.23.2, 00:07:03
B 10.0.0.2/32 [20/0] via 10.0.23.2, 00:07:03
B 10.0.0.3/32 [20/3000] via 10.0.23.2, 00:07:03
B 10.0.0.4/32 [20/43000] via 10.0.23.2, 00:07:15
B 10.0.0.5/32 [20/3000] via 10.0.23.2, 00:07:03
B 10.0.12.0/24 [20/3000] via 10.0.23.2, 00:07:03