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マルチエリアOSPF（マルチエリア構成例の検証）
ここでは、「マルチエリアOSPF（マルチエリア構成例①：R1～R3）」と「マルチエリアOSPF（マルチエリア構成例②：R4～R6）」で構築したネットワークを検証していきます。
ネットワークは下図の構成となります。
ルーティングテーブルの確認
各ルータのルーティングテーブルを確認します。
●R1ルータのルーティングテーブル
R1#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, E - EGP
i - IS-IS, 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
Gateway of last resort is not set
172.17.0.0/16 is variably subnetted, 2 subnets, 2 masks
C 172.17.0.0/16 is directly connected, GigabitEthernet0/1
L 172.17.0.1/32 is directly connected, GigabitEthernet0/1
R 172.18.0.0/16 [120/10] via 172.17.0.2, 00:00:12, GigabitEthernet0/1
R 172.19.0.0/16 [120/10] via 172.17.0.2, 00:00:12, GigabitEthernet0/1
R 172.20.0.0/16 [120/10] via 172.17.0.2, 00:00:12, GigabitEthernet0/1
R 172.21.0.0/16 [120/10] via 172.17.0.2, 00:00:12, GigabitEthernet0/1
192.168.1.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.1.0/24 is directly connected, Loopback0
L 192.168.1.1/32 is directly connected, Loopback0
192.168.2.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.2.0/24 is directly connected, Loopback1
L 192.168.2.1/32 is directly connected, Loopback1
192.168.3.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.3.0/24 is directly connected, Loopback2
L 192.168.3.1/32 is directly connected, Loopback2
192.168.4.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.4.0/24 is directly connected, Loopback3
L 192.168.4.1/32 is directly connected, Loopback3
R 192.168.33.0/24 [120/10] via 172.17.0.2, 00:00:12, GigabitEthernet0/1
R 192.168.34.0/24 [120/10] via 172.17.0.2, 00:00:12, GigabitEthernet0/1
R 192.168.35.0/24 [120/10] via 172.17.0.2, 00:00:12, GigabitEthernet0/1
R 192.168.36.0/24 [120/10] via 172.17.0.2, 00:00:12, GigabitEthernet0/1
RIPのエントリーが7つ現れています。デフォルトの無限大のシードメトリックではなく、「10」が使われたことが分かります。各エントリーの各々のR1ルータからの距離は、異なりますが、すべて「10」となっています。
●R2ルータのルーティングテーブル
R2#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, E - EGP
i - IS-IS, 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
Gateway of last resort is not set
172.17.0.0/16 is variably subnetted, 2 subnets, 2 masks
C 172.17.0.0/16 is directly connected, GigabitEthernet0/0
L 172.17.0.2/32 is directly connected, GigabitEthernet0/0
172.18.0.0/16 is variably subnetted, 2 subnets, 2 masks
C 172.18.0.0/16 is directly connected, GigabitEthernet0/1
L 172.18.0.1/32 is directly connected, GigabitEthernet0/1
O 172.19.0.0/16 [110/2] via 172.18.0.2, 01:00:11, GigabitEthernet0/1
O 172.20.0.0/16 [110/3] via 172.18.0.2, 00:03:30, GigabitEthernet0/1
O IA 172.21.0.0/16 [110/4] via 172.18.0.2, 00:03:30, GigabitEthernet0/1
R 192.168.1.0/24 [120/1] via 172.17.0.1, 00:00:01, GigabitEthernet0/0
R 192.168.2.0/24 [120/1] via 172.17.0.1, 00:00:01, GigabitEthernet0/0
R 192.168.3.0/24 [120/1] via 172.17.0.1, 00:00:01, GigabitEthernet0/0
R 192.168.4.0/24 [120/1] via 172.17.0.1, 00:00:01, GigabitEthernet0/0
O IA 192.168.33.0/24 [110/3] via 172.18.0.2, 01:00:11, GigabitEthernet0/1
O IA 192.168.34.0/24 [110/3] via 172.18.0.2, 01:00:11, GigabitEthernet0/1
O IA 192.168.35.0/24 [110/3] via 172.18.0.2, 01:00:11, GigabitEthernet0/1
O IA 192.168.36.0/24 [110/3] via 172.18.0.2, 01:00:11, GigabitEthernet0/1
RIPネットワーク、OSPFネットワークの各ルートを学習しています。「IA」と表示されているOSPFルートは、他エリアの経路情報であることを示しています。
●R3ルータのルーティングテーブル
R3#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, E - EGP
i - IS-IS, 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
Gateway of last resort is not set
O E2 172.17.0.0/16 [110/100] via 172.18.0.1, 22:13:18, GigabitEthernet0/0
172.18.0.0/16 is variably subnetted, 2 subnets, 2 masks
C 172.18.0.0/16 is directly connected, GigabitEthernet0/0
L 172.18.0.2/32 is directly connected, GigabitEthernet0/0
172.19.0.0/16 is variably subnetted, 2 subnets, 2 masks
C 172.19.0.0/16 is directly connected, GigabitEthernet0/1
L 172.19.0.1/32 is directly connected, GigabitEthernet0/1
O 172.20.0.0/16 [110/2] via 172.19.0.2, 00:05:23, GigabitEthernet0/1
O IA 172.21.0.0/16 [110/3] via 172.19.0.2, 00:05:23, GigabitEthernet0/1
O E2 192.168.1.0/24 [110/100] via 172.18.0.1, 21:51:50, GigabitEthernet0/0
O E2 192.168.2.0/24 [110/100] via 172.18.0.1, 21:51:50, GigabitEthernet0/0
O E2 192.168.3.0/24 [110/100] via 172.18.0.1, 21:51:50, GigabitEthernet0/0
O E2 192.168.4.0/24 [110/100] via 172.18.0.1, 21:51:50, GigabitEthernet0/0
O IA 192.168.33.0/24 [110/2] via 172.19.0.2, 21:41:51, GigabitEthernet0/1
O IA 192.168.34.0/24 [110/2] via 172.19.0.2, 21:41:51, GigabitEthernet0/1
O IA 192.168.35.0/24 [110/2] via 172.19.0.2, 21:41:51, GigabitEthernet0/1
O IA 192.168.36.0/24 [110/2] via 172.19.0.2, 21:41:51, GigabitEthernet0/1
RIPネットワークは、「E2」とマークされています。これはOSPFの外部ルートであることを示しています。「IA」と表示されているOSPFルートは、他エリアの経路情報であることを示しています。
●R4ルータのルーティングテーブル
R4#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, E - EGP
i - IS-IS, 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
Gateway of last resort is not set
O E2 172.17.0.0/16 [110/100] via 172.19.0.1, 01:04:39, GigabitEthernet0/0
O 172.18.0.0/16 [110/2] via 172.19.0.1, 01:04:39, GigabitEthernet0/0
172.19.0.0/16 is variably subnetted, 2 subnets, 2 masks
C 172.19.0.0/16 is directly connected, GigabitEthernet0/0
L 172.19.0.2/32 is directly connected, GigabitEthernet0/0
172.20.0.0/16 is variably subnetted, 2 subnets, 2 masks
C 172.20.0.0/16 is directly connected, GigabitEthernet0/1
L 172.20.0.1/32 is directly connected, GigabitEthernet0/1
O IA 172.21.0.0/16 [110/2] via 172.20.0.2, 00:08:08, GigabitEthernet0/1
O E2 192.168.1.0/24 [110/100] via 172.19.0.1, 01:04:39, GigabitEthernet0/0
O E2 192.168.2.0/24 [110/100] via 172.19.0.1, 01:04:39, GigabitEthernet0/0
O E2 192.168.3.0/24 [110/100] via 172.19.0.1, 01:04:39, GigabitEthernet0/0
O E2 192.168.4.0/24 [110/100] via 172.19.0.1, 01:04:39, GigabitEthernet0/0
192.168.33.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.33.0/24 is directly connected, Loopback0
L 192.168.33.1/32 is directly connected, Loopback0
192.168.34.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.34.0/24 is directly connected, Loopback1
L 192.168.34.1/32 is directly connected, Loopback1
192.168.35.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.35.0/24 is directly connected, Loopback2
L 192.168.35.1/32 is directly connected, Loopback2
192.168.36.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.36.0/24 is directly connected, Loopback3
L 192.168.36.1/32 is directly connected, Loopback3
RIPネットワークは、「E2」とマークされています。これはOSPFの外部ルートであることを示しています。「IA」と表示されているOSPFルートは、他エリアの経路情報であることを示しています。
●R5ルータのルーティングテーブル
R5#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, E - EGP
i - IS-IS, 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
Gateway of last resort is not set
O E2 172.17.0.0/16 [110/100] via 172.20.0.1, 00:10:54, GigabitEthernet0/0
O 172.18.0.0/16 [110/3] via 172.20.0.1, 00:10:54, GigabitEthernet0/0
O 172.19.0.0/16 [110/2] via 172.20.0.1, 00:10:54, GigabitEthernet0/0
172.20.0.0/16 is variably subnetted, 2 subnets, 2 masks
C 172.20.0.0/16 is directly connected, GigabitEthernet0/0
L 172.20.0.2/32 is directly connected, GigabitEthernet0/0
172.21.0.0/16 is variably subnetted, 2 subnets, 2 masks
C 172.21.0.0/16 is directly connected, GigabitEthernet0/1
L 172.21.0.1/32 is directly connected, GigabitEthernet0/1
O E2 192.168.1.0/24 [110/100] via 172.20.0.1, 00:10:54, GigabitEthernet0/0
O E2 192.168.2.0/24 [110/100] via 172.20.0.1, 00:10:54, GigabitEthernet0/0
O E2 192.168.3.0/24 [110/100] via 172.20.0.1, 00:10:54, GigabitEthernet0/0
O E2 192.168.4.0/24 [110/100] via 172.20.0.1, 00:10:54, GigabitEthernet0/0
O IA 192.168.33.0/24 [110/2] via 172.20.0.1, 00:10:54, GigabitEthernet0/0
O IA 192.168.34.0/24 [110/2] via 172.20.0.1, 00:10:54, GigabitEthernet0/0
O IA 192.168.35.0/24 [110/2] via 172.20.0.1, 00:10:54, GigabitEthernet0/0
O IA 192.168.36.0/24 [110/2] via 172.20.0.1, 00:10:54, GigabitEthernet0/0
RIPネットワークは、「E2」とマークされています。これはOSPFの外部ルートであることを示しています。「IA」と表示されているOSPFルートは、他エリアの経路情報であることを示しています。
●R6ルータのルーティングテーブル
R6#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, E - EGP
i - IS-IS, 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
Gateway of last resort is not set
O E2 172.17.0.0/16 [110/100] via 172.21.0.1, 00:14:00, GigabitEthernet0/0
O IA 172.18.0.0/16 [110/4] via 172.21.0.1, 00:14:00, GigabitEthernet0/0
O IA 172.19.0.0/16 [110/3] via 172.21.0.1, 00:14:00, GigabitEthernet0/0
O IA 172.20.0.0/16 [110/2] via 172.21.0.1, 00:14:00, GigabitEthernet0/0
172.21.0.0/16 is variably subnetted, 2 subnets, 2 masks
C 172.21.0.0/16 is directly connected, GigabitEthernet0/0
L 172.21.0.2/32 is directly connected, GigabitEthernet0/0
O E2 192.168.1.0/24 [110/100] via 172.21.0.1, 00:14:00, GigabitEthernet0/0
O E2 192.168.2.0/24 [110/100] via 172.21.0.1, 00:14:00, GigabitEthernet0/0
O E2 192.168.3.0/24 [110/100] via 172.21.0.1, 00:14:00, GigabitEthernet0/0
O E2 192.168.4.0/24 [110/100] via 172.21.0.1, 00:14:00, GigabitEthernet0/0
O IA 192.168.33.0/24 [110/3] via 172.21.0.1, 00:14:00, GigabitEthernet0/0
O IA 192.168.34.0/24 [110/3] via 172.21.0.1, 00:14:00, GigabitEthernet0/0
O IA 192.168.35.0/24 [110/3] via 172.21.0.1, 00:14:00, GigabitEthernet0/0
O IA 192.168.36.0/24 [110/3] via 172.21.0.1, 00:14:00, GigabitEthernet0/0
RIPネットワークは、「E2」とマークされています。これはOSPFの外部ルートであることを示しています。「IA」と表示されているOSPFルートは、他エリアの経路情報であることを示しています。
ASBRであることの確認（R2ルータ）
R2ルータがどのタイプのOSPFルータを担当しているかを確認します。確認には「show ip ospf」コマンドを使用します。
●R2ルータの「show ip ospf」の出力
R2#show ip ospf
Routing Process "ospf 1" with ID 172.18.0.1
Supports only single TOS(TOS0) routes
Supports opaque LSA
It is an autonomous system boundary router
SPF schedule delay 5 secs, Hold time between two SPFs 10 secs
Minimum LSA interval 5 secs. Minimum LSA arrival 1 secs
Number of external LSA 5. Checksum Sum 0x02638a
Number of opaque AS LSA 0. Checksum Sum 0x000000
Number of DCbitless external and opaque AS LSA 0
Number of DoNotAge external and opaque AS LSA 0
Number of areas in this router is 1. 1 normal 0 stub 0 nssa
External flood list length 0
Area BACKBONE(0)
Number of interfaces in this area is 1
Area has no authentication
SPF algorithm executed 25 times
Area ranges are
Number of LSA 12. Checksum Sum 0x038968
Number of opaque link LSA 0. Checksum Sum 0x000000
Number of DCbitless LSA 0
Number of indication LSA 0
Number of DoNotAge LSA 0
Flood list length 0緑のマーカーから、R2ルータがASBRであることが分かります。
ABRであることの確認（R4ルータ）
R4ルータでどのタイプのOSPFルータを担当しているかを確認します。確認には「show ip ospf」コマンドを使用します。
●R4ルータの「show ip ospf」の出力
R4#show ip ospf
Routing Process "ospf 1" with ID 192.168.36.1
Supports only single TOS(TOS0) routes
Supports opaque LSA
It is an area border router
SPF schedule delay 5 secs, Hold time between two SPFs 10 secs
Minimum LSA interval 5 secs. Minimum LSA arrival 1 secs
Number of external LSA 5. Checksum Sum 0x02638a
Number of opaque AS LSA 0. Checksum Sum 0x000000
Number of DCbitless external and opaque AS LSA 0
Number of DoNotAge external and opaque AS LSA 0
Number of areas in this router is 2. 2 normal 0 stub 0 nssa
External flood list length 0
Area BACKBONE(0)
Number of interfaces in this area is 2
Area has no authentication
SPF algorithm executed 19 times
Area ranges are
Number of LSA 12. Checksum Sum 0x038968
Number of opaque link LSA 0. Checksum Sum 0x000000
Number of DCbitless LSA 0
Number of indication LSA 0
Number of DoNotAge LSA 0
Flood list length 0
Area 2
Number of interfaces in this area is 4
Area has no authentication
SPF algorithm executed 7 times
Area ranges are
Number of LSA 6. Checksum Sum 0x0425a2
Number of opaque link LSA 0. Checksum Sum 0x000000
Number of DCbitless LSA 0
Number of indication LSA 0
Number of DoNotAge LSA 0
Flood list length 0
ピンクのマーカーから、R4ルータは、ABRであることが分かります。
ABRであることの確認（R5ルータ）
R5ルータでどのタイプのOSPFルータを担当しているかを確認します。確認には「show ip ospf」コマンドを使用します。
●R5ルータの「show ip ospf」の出力
R5#show ip ospf
Routing Process "ospf 1" with ID 172.21.0.1
Supports only single TOS(TOS0) routes
Supports opaque LSA
It is an area border router
SPF schedule delay 5 secs, Hold time between two SPFs 10 secs
Minimum LSA interval 5 secs. Minimum LSA arrival 1 secs
Number of external LSA 5. Checksum Sum 0x02618b
Number of opaque AS LSA 0. Checksum Sum 0x000000
Number of DCbitless external and opaque AS LSA 0
Number of DoNotAge external and opaque AS LSA 0
Number of areas in this router is 2. 2 normal 0 stub 0 nssa
External flood list length 0
Area BACKBONE(0)
Number of interfaces in this area is 1
Area has no authentication
SPF algorithm executed 7 times
Area ranges are
Number of LSA 12. Checksum Sum 0x038968
Number of opaque link LSA 0. Checksum Sum 0x000000
Number of DCbitless LSA 0
Number of indication LSA 0
Number of DoNotAge LSA 0
Flood list length 0
Area 1
Number of interfaces in this area is 1
Area has no authentication
SPF algorithm executed 2 times
Area ranges are
Number of LSA 11. Checksum Sum 0x04bb35
Number of opaque link LSA 0. Checksum Sum 0x000000
Number of DCbitless LSA 0
Number of indication LSA 0
Number of DoNotAge LSA 0
Flood list length 0ピンクのマーカーから、R5ルータは、ABRであることが分かります。
次の「マルチエリアOSPF（エリアの種類）」では、OSPFネットワークにおけるエリアの役割と種類についての概要について解説します。