In a network, there is a possibility that it is running on both OSPF and RIP and the route of OSPF cannot be advertised to RIP by itself. Similarly, routes of RIP cannot be advertised to OSPF by itself.
Now the question arises how can R2 reach the routes advertised on R1?
We can also consider this as how can routes of OSPF and RIP reach each other.
Guessed right, we can make use of Redistribution to advertise routes between each other.
Route Redistribution is a process that helps to exchange routing information from one routing protocol to another. It allows routes from one routing protocol to be advertised into another.
Let us now see the configuration to redistribute routes between RIP and OSPF.
R1: –
R1(config)#interface GigabitEthernet0/0/0
R1(config-if)#ip address 192.168.12.1 255.255.255.0
R1(config-if)#no shutdown
R1(config-if)#exit
R1(config)#interface loopback 1
R1(config-if)#ip address 1.1.1.1 255.255.255.0
R1(config-if)#exit
R1(config)#router ospf 1
R1(config-router)#network 1.1.1.0 0.0.0.255 area 0
R1(config-router)#network 192.168.12.0 0.0.0.255 area 0
R2: –
R2(config)#interface GigabitEthernet0/0/0
R2(config-if)#ip address 192.168.23.1 255.255.255.0
R2(config-if)#no shutdown
R2(config)#interface loopback 1
R2(config-if)#ip address 2.2.2.1 255.255.255.0
R2(config-if)#exit
R2(config)#router rip
R2(config-router)#version 2
R2(config-router)#no auto-summary
R2(config-router)#network 192.168.23.0
R2(config-router)#network 2.2.2.0
R2(config-router)#exit
R3: –
R3(config)#interface GigabitEthernet0/0/0
R3(config-if)#ip address 192.168.12.2 255.255.255.0
R3(config-if)#no shutdown
R3(config-if)#exit
R3(config)#interface GigabitEthernet0/0/1
R3(config-if)#ip address 192.168.23.2 255.255.255.0
R3(config-if)#no shutdown
R3(config)#router ospf 1
R3(config-router)#network 192.168.12.0 0.0.0.255 area 0
R3(config-router)#exit
R3(config)#router rip
R3(config-router)#version 2
R3(config-router)#no auto-summary
R3(config-router)#network 192.168.23.0
R3(config-router)#exit
Let us check the routes before redistribution.
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
1.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 1.1.1.0/24 is directly connected, Loopback1
L 1.1.1.1/32 is directly connected, Loopback1
192.168.12.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.12.0/24 is directly connected, GigabitEthernet0/0/0
L 192.168.12.1/32 is directly connected, GigabitEthernet0/0/0
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
2.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 2.2.2.0/24 is directly connected, Loopback1
L 2.2.2.1/32 is directly connected, Loopback1
192.168.23.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.23.0/24 is directly connected, GigabitEthernet0/0/0
L 192.168.23.1/32 is directly connected, GigabitEthernet0/0/0
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
1.0.0.0/32 is subnetted, 1 subnets
O 1.1.1.1/32 [110/2] via 192.168.12.1, 00:04:56, GigabitEthernet0/0/0
2.0.0.0/24 is subnetted, 1 subnets
R 2.2.2.0/24 [120/1] via 192.168.23.1, 00:00:07, GigabitEthernet0/0/1
192.168.12.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.12.0/24 is directly connected, GigabitEthernet0/0/0
L 192.168.12.2/32 is directly connected, GigabitEthernet0/0/0
192.168.23.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.23.0/24 is directly connected, GigabitEthernet0/0/1
L 192.168.23.2/32 is directly connected, GigabitEthernet0/0/1
REDISTRIBUTION:-
R3(config)#router rip
R3(config-router)#redistribute ospf ?
<1-65535> Process ID
R3(config-router)#redistribute ospf 1 ?
match Redistribution of OSPF routes
metric Metric for redistributed routes
<cr>
R3(config-router)#redistribute ospf 1 metric ?
<0-16> Default metric
transparent Transparently redistribute metric
R3(config-router)#redistribute ospf 1 metric 5 ?
match Redistribution of OSPF routes
<cr>
R3(config-router)#redistribute ospf 1 metric 5
R3(config-router)#exit
R3(config)#router ospf 1
R3(config-router)#redistribute rip
R3(config-router)#redistribute rip subnets ?
tag Set tag for routes redistributed into OSPF
<cr>
R3(config-router)#redistribute rip subnets
R3(config-router)#exit
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
1.0.0.0/32 is subnetted, 1 subnets
O 1.1.1.1/32 [110/2] via 192.168.12.1, 00:08:51, GigabitEthernet0/0/0
2.0.0.0/24 is subnetted, 1 subnets
R 2.2.2.0/24 [120/1] via 192.168.23.1, 00:00:21, GigabitEthernet0/0/1
192.168.12.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.12.0/24 is directly connected, GigabitEthernet0/0/0
L 192.168.12.2/32 is directly connected, GigabitEthernet0/0/0
192.168.23.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.23.0/24 is directly connected, GigabitEthernet0/0/1
L 192.168.23.2/32 is directly connected, GigabitEthernet0/0/1
VERIFICATION:-
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
1.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 1.1.1.0/24 is directly connected, Loopback1
L 1.1.1.1/32 is directly connected, Loopback1
2.0.0.0/24 is subnetted, 1 subnets
O E2 2.2.2.0/24 [110/20] via 192.168.12.2, 00:00:29, GigabitEthernet0/0/0
192.168.12.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.12.0/24 is directly connected, GigabitEthernet0/0/0
L 192.168.12.1/32 is directly connected, GigabitEthernet0/0/0
O E2 192.168.23.0/24 [110/20] via 192.168.12.2, 00:00:29, GigabitEthernet0/0/0
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
1.0.0.0/32 is subnetted, 1 subnets
R 1.1.1.1/32 [120/5] via 192.168.23.2, 00:00:07, GigabitEthernet0/0/0
2.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 2.2.2.0/24 is directly connected, Loopback1
L 2.2.2.1/32 is directly connected, Loopback1
R 192.168.12.0/24 [120/5] via 192.168.23.2, 00:00:07, GigabitEthernet0/0/0
192.168.23.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.23.0/24 is directly connected, GigabitEthernet0/0/0
L 192.168.23.1/32 is directly connected, GigabitEthernet0/0/0
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
1.0.0.0/32 is subnetted, 1 subnets
O 1.1.1.1/32 [110/2] via 192.168.12.1, 00:12:21, GigabitEthernet0/0/0
2.0.0.0/24 is subnetted, 1 subnets
R 2.2.2.0/24 [120/1] via 192.168.23.1, 00:00:08, GigabitEthernet0/0/1
192.168.12.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.12.0/24 is directly connected, GigabitEthernet0/0/0
L 192.168.12.2/32 is directly connected, GigabitEthernet0/0/0
192.168.23.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.23.0/24 is directly connected, GigabitEthernet0/0/1
L 192.168.23.2/32 is directly connected, GigabitEthernet0/0/1
