Cisco ospf 默認路由綜合實驗
一、實驗拓撲：
R1、R2模擬內部網絡路由器，運行OSPF協議，R3模擬互聯網路由器，現需要通過R2上配置默認路由，讓R1能學習到R3的3.3.3.3路由條目。
二、實驗步驟：
R1:
interface Loopback0
ip address 1.1.1.1 255.255.255.0
interface FastEthernet0/0
ip address 192.168.1.1 255.255.255.0
duplex auto
speed auto
router ospf 10
router-id 1.1.1.1
log-adjacency-changes
network 1.1.1.0 0.0.0.255 area 0
network 192.168.1.0 0.0.0.255 area 0
R2:
interface FastEthernet0/0
ip address 192.168.1.2 255.255.255.0
duplex auto
interface Serial1/0
ip address 221.16.1.1 255.255.255.252
serial restart-delay 0
router ospf 10
router-id 2.2.2.2
log-adjacency-changes
network 192.168.1.0 0.0.0.255 area 0
default-information originate always
R3:
interface Loopback0
ip address 3.3.3.3 255.255.255.0
interface Serial0/0
ip address 221.16.1.2 255.255.255.252
serial restart-delay 0
ip route 0.0.0.0 0.0.0.0 Serial0/0
查看R1和R2的鄰接關係和路由表：
R1#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
2.2.2.2 1 FULL/BDR 00:00:35 192.168.1.2 FastEthernet0/0
R1#show 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, 1 subnets
C 1.1.1.0 is directly connected, Loopback0
C 192.168.1.0/24 is directly connected, FastEthernet0/0
O*E2 0.0.0.0/0 [110/1] via 192.168.1.2, 00:02:07, FastEthernet0/0
R2#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
1.1.1.1 1 FULL/DR 00:00:35 192.168.1.1 FastEthernet0/0
R2#show 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 0.0.0.0 to network 0.0.0.0
1.0.0.0/32 is subnetted, 1 subnets
O 1.1.1.1 [110/2] via 192.168.1.1, 00:01:53, FastEthernet0/0
221.16.1.0/30 is subnetted, 1 subnets
C 221.16.1.0 is directly connected, Serial1/0
C 192.168.1.0/24 is directly connected, FastEthernet0/0
S* 0.0.0.0/0 is directly connected, Serial1/0
測試從R1到3.3.3.3的網絡連通性：
R1#ping 3.3.3.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 408/508/640 ms
2、通過上個實驗觀察到R1學到O*E2的度量值爲1，現在擴大度量值：
R2上配置：
R2(config)#router ospf 10
R2(config-router)#default-information originate always metric 30
測試R1路由表：
R1#show ip route ospf
O*E2 0.0.0.0/0 [110/30] via 192.168.1.2, 00:00:13, FastEthernet0/0 //度量值變成30了，當然R1 PING 3.3.3.3肯定還是通的。
3、通過上個實驗觀察到R1的OE2度量值變成30，現在需要把OE2變成OE1，配置：
R2(config)#router ospf 10
R2(config-router)#default-information originate always metric-type 1 metric 30
查看R1路由表：
R1#show 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, 1 subnets
C 1.1.1.0 is directly connected, Loopback0
C 192.168.1.0/24 is directly connected, FastEthernet0/0
O*E1 0.0.0.0/0 [110/31] via 192.168.1.2, 00:00:11, FastEthernet0/0
//31的度量值的算法：宣告外部路由進來爲30，從R2到192.168.1.1的METRIC=1，根據OE1的度量值算法爲：內部到ASBR+外部路徑度量值=31
R2#show ip ospf database router
LS age: 1356
Options: (No TOS-capability, DC)
LS Type: Router Links
Link State ID: 1.1.1.1
Advertising Router: 1.1.1.1
LS Seq Number: 80000003
Checksum: 0x64D8
Length: 48
Number of Links: 2
Link connected to: a Transit Network
(Link ID) Designated Router address: 192.168.1.1
(Link Data) Router Interface address: 192.168.1.1
Number of TOS metrics: 0
TOS 0 Metrics: 1
4、現在R3上增加網段4.4.4.0/24，R1 PING 3.3.3.0/24,4.4.4.0/24情況：
R1#ping 3.3.3.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 364/471/568 ms
R1#ping 4.4.4.4
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 4.4.4.4, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 284/417/620 ms
R2上配置路由策略過濾掉3.3.3.0/24網段：
R2(config)#access-list 1 permit 3.3.3.0 0.0.0.255
R2(config)#route-map ccna permit 10
R2(config-route-map)#match ip address 1
R2(config-route-map)#set metr
R2(config-route-map)#set metric 30
R2(config-route-map)#end
R2(config)#router ospf 10
R2(config-router)#no default-information originate always route-map ccna
R1#ping 4.4.4.4
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 4.4.4.4, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 284/417/620 ms
R1#ping 3.3.3.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
R1#show 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, 1 subnets
C 1.1.1.0 is directly connected, Loopback0
C 192.168.1.0/24 is directly connected, FastEthernet0/0
O*E1 0.0.0.0/0 [110/31] via 192.168.1.2, 00:02:51, FastEthernet0/0