GNS3上でOSPFのトータリースタブを構成するまでの手順を再確認してみます。
[RouterA]
interface Loopback0 ip address 1.1.1.1 255.255.255.255 ! interface Ethernet0/0 ip address 10.0.1.2 255.255.255.0 half-duplex ! router ospf 1 log-adjacency-changes network 10.0.1.0 0.0.0.255 area 1 !
[RouterB]
interface Loopback0 ip address 2.2.2.2 255.255.255.255 ! interface Ethernet0/0 ip address 10.0.1.1 255.255.255.0 half-duplex ! interface Ethernet0/1 ip address 10.0.0.1 255.255.255.0 half-duplex ! router ospf 1 log-adjacency-changes network 10.0.0.0 0.0.0.255 area 0 network 10.0.1.0 0.0.0.255 area 1 !
[RouterC]
interface Loopback0 ip address 3.3.3.3 255.255.255.255 ! interface Ethernet0/0 ip address 10.0.0.2 255.255.255.0 half-duplex ! interface Ethernet0/1 ip address 192.168.1.1 255.255.255.0 half-duplex ! router ospf 1 log-adjacency-changes redistribute rip subnets :RIPの経路をOSPFで再配布 network 10.0.0.0 0.0.0.255 area 0 default-metric 30 :OSPFへ再配布するときのコスト ! router rip network 192.168.1.0 !
[RouterD]
interface Loopback0 ip address 4.4.4.4 255.255.255.255 ! interface Ethernet0/0 ip address 192.168.1.2 255.255.255.0 half-duplex ! interface Ethernet0/1 ip address 192.168.110.1 255.255.255.0 half-duplex ! interface Ethernet0/2 ip address 192.168.120.1 255.255.255.0 half-duplex ! router rip network 192.168.1.0 network 192.168.110.0 network 192.168.120.0 ! ip route 0.0.0.0 0.0.0.0 192.168.1.1 !
RouterAのOSPFデータベースを確認します。
RouterA#sh ip ospf database OSPF Router with ID (1.1.1.1) (Process ID 1) Router Link States (Area 1) :Type1 Link ID ADV Router Age Seq# Checksum Link count 1.1.1.1 1.1.1.1 1871 0x80000002 0x0031D6 1 2.2.2.2 2.2.2.2 1872 0x80000002 0x00D926 1 Net Link States (Area 1) :Type2 Link ID ADV Router Age Seq# Checksum 10.0.1.1 2.2.2.2 1872 0x80000001 0x0042D7 Summary Net Link States (Area 1) :type3 Link ID ADV Router Age Seq# Checksum 10.0.0.0 2.2.2.2 1913 0x80000001 0x002FF1 Summary ASB Link States (Area 1) :Type4 Link ID ADV Router Age Seq# Checksum 3.3.3.3 2.2.2.2 1872 0x80000001 0x001905 Type-5 AS External Link States :Type5 Link ID ADV Router Age Seq# Checksum Tag 192.168.1.0 3.3.3.3 1918 0x80000001 0x0035EA 0 192.168.110.0 3.3.3.3 1917 0x80000001 0x008131 0 192.168.120.0 3.3.3.3 1917 0x80000001 0x001395 0
LSA2~LSA5はこんな感じで配送されてきます。LSA1は各ルータが生成し配布します。
ここからArea1をスタブにします。設定はRoterAとRouterBの両方に施す必要があるので注意。
RouterA(config-router)#area 1 stub
RouterB(config-router)#area 1 stub
RouterAのOSPFデータベースを見てみると、先ほどと違いType4、Type5が無くなり代わりにType3でデフォルトルートが通知されてくるのがわかります。
RouterA#sh ip ospf database
OSPF Router with ID (1.1.1.1) (Process ID 1)
Router Link States (Area 1)
Link ID ADV Router Age Seq# Checksum Link count
1.1.1.1 1.1.1.1 54 0x80000006 0x0047BE 1
2.2.2.2 2.2.2.2 55 0x80000006 0x00EF0E 1
Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
10.0.1.1 2.2.2.2 50 0x80000005 0x0058BF
Summary Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
0.0.0.0 2.2.2.2 56 0x80000001 0x0075C0
10.0.0.0 2.2.2.2 56 0x80000004 0x0047D8
ルーティングテーブルも確認。
RouterA#sh ip route
Codes: 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
Gateway of last resort is 10.0.1.1 to network 0.0.0.0
1.0.0.0/32 is subnetted, 1 subnets
C 1.1.1.1 is directly connected, Loopback0
10.0.0.0/24 is subnetted, 2 subnets
O IA 10.0.0.0 [110/20] via 10.0.1.1, 00:05:13, Ethernet0/0
C 10.0.1.0 is directly connected, Ethernet0/0
O*IA 0.0.0.0/0 [110/11] via 10.0.1.1, 00:05:13, Ethernet0/0
さらに外部エリア(ここではArea0)の経路情報もデフォルトルートで代替させる「トータリースタブ」を設定してみます。
RouterA(config-router)#area 1 stub no-summary
RouterB(config-router)#area 1 stub no-summary
OSPFデータベースを確認。
RouterA#sh ip ospf database
OSPF Router with ID (1.1.1.1) (Process ID 1)
Router Link States (Area 1)
Link ID ADV Router Age Seq# Checksum Link count
1.1.1.1 1.1.1.1 654 0x80000006 0x0047BE 1
2.2.2.2 2.2.2.2 655 0x80000006 0x00EF0E 1
Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
10.0.1.1 2.2.2.2 650 0x80000005 0x0058BF
Summary Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
0.0.0.0 2.2.2.2 60 0x80000002 0x0073C1
ルーティングテーブルも確認します。
RouterA#sh ip route
Codes: 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
Gateway of last resort is 10.0.1.1 to network 0.0.0.0
1.0.0.0/32 is subnetted, 1 subnets
C 1.1.1.1 is directly connected, Loopback0
10.0.0.0/24 is subnetted, 1 subnets
C 10.0.1.0 is directly connected, Ethernet0/0
O*IA 0.0.0.0/0 [110/11] via 10.0.1.1, 00:01:29, Ethernet0/0