The following will be a demonstration of one way route redistribution between RIP and OSPF routing domains, and how to get two way communication between the two routing domains with a static route, rather than redistributing both protocols on the ASBR R3:

OSPFtoRIP_Redist_Top

After configuring the NBMA network which is now a RIPv2 domain with the proper commands:

R1(config)#int s0/0
R1(config-if)#no ip split-horizon
R1(config-if)#router rip
R1(config-router)#ver 2
R1(config-router)#no auto
R1(config-router)#network 172.12.123.0
R1(config-router)#network 10.1.1.0

Of course for the NBMA the Hub needs the no ip split-horizon configured for it to propagate routes correctly for RIP and EIGRP, and configured R2 and R3 for RIP. Then I connected the Fa0/0 interface of each OSPF router to my 3560, place them in one broadcast domain.

While I have 4 routers on 1 Broadcast segment, I wanted to grab an example of a lesson earlier in OSPF, that the two DROTHER routers will show the other DROTHERs State as 2WAY/DROTHER ***ONLY BETWEEN THE DROTHERS, THE DR AND BDR SHOWS THEM AS FULL/DROTHER***:

R5#show ip ospf nei

Neighbor ID     Pri   State           Dead Time   Address         Interface
2.2.2.2           1   FULL/DROTHER    00:00:39    30.1.1.2        FastEthernet0/0
3.3.3.3           1   FULL/DROTHER    00:00:38    30.1.1.3        FastEthernet0/0
4.4.4.4           1   FULL/DR         00:00:36    30.1.1.4        FastEthernet0/0

R4#show ip ospf nei

Neighbor ID     Pri   State           Dead Time   Address         Interface
2.2.2.2           1   FULL/DROTHER    00:00:30    30.1.1.2        FastEthernet0/0
3.3.3.3           1   FULL/DROTHER    00:00:32    30.1.1.3        FastEthernet0/0
5.5.5.5           1   FULL/BDR        00:00:32    30.1.1.5        FastEthernet0/0

R3#show ip ospf nei

Neighbor ID     Pri   State           Dead Time   Address         Interface
2.2.2.2           1   2WAY/DROTHER    00:00:32    30.1.1.2        FastEthernet0/0
4.4.4.4           1   FULL/DR         00:00:31    30.1.1.4        FastEthernet0/0
5.5.5.5           1   FULL/BDR        00:00:33    30.1.1.5        FastEthernet0/0

R2#show ip ospf nei

Neighbor ID     Pri   State           Dead Time   Address         Interface
3.3.3.3           1   2WAY/DROTHER    00:00:34    30.1.1.3        FastEthernet0/0
4.4.4.4           1   FULL/DR         00:00:39    30.1.1.4        FastEthernet0/0
5.5.5.5           1   FULL/BDR        00:00:31    30.1.1.5        FastEthernet0/0

I will spare the further router output, but these neighbors will learn routes and have Layer 3 connectivity as a normal Adjacency, however they will get stuck in this State in eachothers “show ip ospf nei” table however this is not the the more complex issue known as “stuck in 2way” oddly enough.

Now, back to Redistribution and Static routing.

 

To start redistribution, I first wanted to test one way redistribution, and returning traffic with a static route so I issued the following commands:

R3(config)#router rip
R3(config-router)#redistribute connect
R3(config-router)#redistribute ospf 1 metric 2

So as of now the OSPF routing domain is being redistributed into RIP, along with connected routes on R3, however the oddity with RIP is that you don’t need to use “redistribute connected subnets” – Only “redistribute connected” much alike how you don’t enter subnet mask information into the network statements during router configuration for RIP.

So now the OSPF routers are obviously not getting RIP routes injected to them yet, however I did want to verify from the back end router R1 to make sure everything is looking good and confirming that the correct response to a ping would occur:

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 not set

2.0.0.0/32 is subnetted, 1 subnets
R       2.2.2.2 [120/1] via 172.12.123.2, 00:00:10, Serial0/0
3.0.0.0/32 is subnetted, 1 subnets
R       3.3.3.3 [120/1] via 172.12.123.3, 00:00:04, Serial0/0
4.0.0.0/32 is subnetted, 1 subnets
R       4.4.4.4 [120/2] via 172.12.123.3, 00:00:04, Serial0/0
5.0.0.0/32 is subnetted, 1 subnets
R       5.5.5.5 [120/2] via 172.12.123.3, 00:00:04, Serial0/0
172.12.0.0/24 is subnetted, 1 subnets
C       172.12.123.0 is directly connected, Serial0/0
10.0.0.0/24 is subnetted, 1 subnets
C       10.1.1.0 is directly connected, Loopback1
30.0.0.0/24 is subnetted, 1 subnets
R       30.1.1.0 [120/1] via 172.12.123.3, 00:00:20, Serial0/0

R1#ping 5.5.5.5

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds:
…..
Success rate is 0 percent (0/5)

The RIP domain knows about R5’s loopback of 5.5.5.5, however no Redistribution has been done to advertise a return route into the OSPF routing domain, and I did this on purpose so I could confirm that static routes are straight forward with Redistribution:

R5(config)#ip route 172.12.123.0 255.255.255.0 30.1.1.3
ASR#1
[Resuming connection 1 to r1 … ]
R1#ping 5.5.5.5
*Mar  1 12:13:26.272: %SYS-5-CONFIG_I: Configured from console by console

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 64/65/69 ms

And there it is! Simply adding the ip route statement to R5 allowed the two way communication we would have gotten, had we also redistributed RIP routes into OSPF on the ASBR R3 – However that can lead to sub-optimal routing at it’s finest which I will cover on my next post.

I was going to add it to this post, but creating a Topology in paint using two different colors took it out of me, next up on the post list will be working with AD to overcome sub-optimal routing!