无论是单独使用当作一个命令使用，还是做为其它命令的参数都是产生External LSA(type5/7)。
特例是are area-id nssa no-summary default-information-originate这个复合命令，default-information-originate在此命令中以参数形式出现。但no-summary与default-information-originate两参数功能是一样的，在此area中的基础参数no-summary优先生效，进而使用type-3的LSA产生一个默认路由到区域内。
实例1>
r2#sh run | begin router
router ospf 100
router-id 10.0.0.2
log-adjacency-changes
area 1 nssa default-information-originate
area 1 default-cost 100
network 172.16.2.0 0.0.0.255 area 1
network 172.16.3.0 0.0.0.255 area 1
network 192.168.0.0 0.0.0.255 area 0
network 192.168.1.0 0.0.0.255 area 1
-------------------------------------------------
r1#sh run | begin router
router ospf 100
router-id 10.0.0.1
log-adjacency-changes
area 1 nssa
redistribute connected subnets
network 172.16.0.0 0.0.0.255 area 1
network 172.16.1.0 0.0.0.255 area 1
network 192.168.1.0 0.0.0.255 area 1
-------------------------------------------------
r1#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 192.168.1.2 to network 0.0.0.0
1.0.0.0/24 is subnetted, 4 subnets
C 1.1.0.0 is directly connected, Loopback6
C 1.1.1.0 is directly connected, Loopback5
C 1.1.2.0 is directly connected, Loopback7
C 1.1.3.0 is directly connected, Loopback8
2.0.0.0/24 is subnetted, 1 subnets
O IA 2.2.2.0 [110/65] via 192.168.1.2, 00:07:47, Serial1/0
172.16.0.0/24 is subnetted, 4 subnets
C 172.16.0.0 is directly connected, Loopback0
C 172.16.1.0 is directly connected, Loopback1
O 172.16.2.0 [110/65] via 192.168.1.2, 00:09:32, Serial1/0
O 172.16.3.0 [110/65] via 192.168.1.2, 00:09:32, Serial1/0
O IA 192.168.0.0/24 [110/128] via 192.168.1.2, 00:07:47, Serial1/0
C 192.168.1.0/24 is directly connected, Serial1/0
O*N2 0.0.0.0/0 [110/100] via 192.168.1.2, 00:07:30, Serial1/0
-------------------------------------------------
实例2>
r2#sh run | begin router
router ospf 100
router-id 10.0.0.2
log-adjacency-changes
network 172.16.2.0 0.0.0.255 area 1
network 172.16.3.0 0.0.0.255 area 1
network 192.168.0.0 0.0.0.255 area 0
network 192.168.1.0 0.0.0.255 area 1
default-information originate always
------------------------------------------------
r1#sh run | begin router
router ospf 100
router-id 10.0.0.1
log-adjacency-changes
redistribute connected subnets
network 172.16.0.0 0.0.0.255 area 1
network 172.16.1.0 0.0.0.255 area 1
network 192.168.1.0 0.0.0.255 area 1
------------------------------------------------
r1#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 192.168.1.2 to network 0.0.0.0
2.0.0.0/24 is subnetted, 1 subnets
O IA 2.2.2.0 [110/65] via 192.168.1.2, 00:01:47, Serial1/0
172.1.0.0/24 is subnetted, 4 subnets
O E2 172.1.1.0 [110/20] via 192.168.1.2, 00:01:47, Serial1/0
O E2 172.1.0.0 [110/20] via 192.168.1.2, 00:01:47, Serial1/0
O E2 172.1.3.0 [110/20] via 192.168.1.2, 00:01:47, Serial1/0
O E2 172.1.2.0 [110/20] via 192.168.1.2, 00:01:47, Serial1/0
172.16.0.0/24 is subnetted, 4 subnets
C 172.16.0.0 is directly connected, Loopback0
C 172.16.1.0 is directly connected, Loopback1
O 172.16.2.0 [110/65] via 192.168.1.2, 00:01:48, Serial1/0
O 172.16.3.0 [110/65] via 192.168.1.2, 00:01:48, Serial1/0
O IA 192.168.0.0/24 [110/128] via 192.168.1.2, 00:01:48, Serial1/0
C 192.168.1.0/24 is directly connected, Serial1/0
O*E2 0.0.0.0/0 [110/1] via 192.168.1.2, 00:01:34, Serial1/0
------------------------------------------
r3#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 192.168.0.1 to network 0.0.0.0
1.0.0.0/24 is subnetted, 4 subnets
O E2 1.1.0.0 [110/20] via 192.168.0.1, 00:12:46, Serial1/0
O E2 1.1.1.0 [110/20] via 192.168.0.1, 00:12:46, Serial1/0
O E2 1.1.2.0 [110/20] via 192.168.0.1, 00:12:46, Serial1/0
O E2 1.1.3.0 [110/20] via 192.168.0.1, 00:12:46, Serial1/0
2.0.0.0/24 is subnetted, 1 subnets
O 2.2.2.0 [110/65] via 192.168.0.1, 00:12:46, Serial1/0
172.1.0.0/24 is subnetted, 4 subnets
C 172.1.1.0 is directly connected, Loopback0
C 172.1.0.0 is directly connected, Loopback1
C 172.1.3.0 is directly connected, Loopback3
C 172.1.2.0 is directly connected, Loopback2
C 192.168.0.0/24 is directly connected, Serial1/0
O IA 192.168.1.0/24 [110/128] via 192.168.0.1, 00:12:47, Serial1/0
O*E2 0.0.0.0/0 [110/1] via 192.168.0.1, 00:12:33, Serial1/0
--------------------------------------------------
++++++++++++++++++++++++++++++++++++++++++++++
此处default-information-oraginate命令单独使用，因其不特定于一个area，所以area0/1的路由器全收到些默认路由。
++++++++++++++++++++++++++++++++++++++++++++++
特例：
r2#sh run | begin router
router ospf 100
router-id 10.0.0.2
log-adjacency-changes
area 1 nssa no-summary default-information-originate
network 2.2.2.0 0.0.0.255 area 0
network 172.16.2.0 0.0.0.255 area 1
network 172.16.3.0 0.0.0.255 area 1
network 192.168.0.0 0.0.0.255 area 0
network 192.168.1.0 0.0.0.255 area 1
-----------------------------------------------------------
r1#sh run | begin router
router ospf 100
router-id 10.0.0.1
log-adjacency-changes
area 1 nssa
redistribute connected subnets
network 172.16.0.0 0.0.0.255 area 1
network 172.16.1.0 0.0.0.255 area 1
network 192.168.1.0 0.0.0.255 area 1
-------------------------------------------------
r1#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 192.168.1.2 to network 0.0.0.0
1.0.0.0/24 is subnetted, 4 subnets
C 1.1.0.0 is directly connected, Loopback6
C 1.1.1.0 is directly connected, Loopback5
C 1.1.2.0 is directly connected, Loopback7
C 1.1.3.0 is directly connected, Loopback8
172.16.0.0/24 is subnetted, 4 subnets
C 172.16.0.0 is directly connected, Loopback0
C 172.16.1.0 is directly connected, Loopback1
O 172.16.2.0 [110/65] via 192.168.1.2, 00:11:20, Serial1/0
O 172.16.3.0 [110/65] via 192.168.1.2, 00:11:20, Serial1/0
C 192.168.1.0/24 is directly connected, Serial1/0
O*IA 0.0.0.0/0 [110/164] via 192.168.1.2, 00:01:01, Serial1/0
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