IGP Redistributed routes not redistributed into BGP

kent2612 · February 19, 2022, 1:13pm

Hi Rene,
I have a question about redistribution of routes.

R1 fa0/0 and R3 fa0/1 are OSPF neighbors
R1 fa0/1, R2 and R3 fa1/0 are EIGRP neighbors
R3 fa0/0 and R4 are iBGP neighbors
Redistribution only happens between:

OSPF and EIGRP
EIGRP and BGP
Without redistribution between OSPF and BGP, is there a way for R4 is learn 192.168.13.0/24 routes and R1 to learn 10.1.1.0/24 routes?

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 not set

C    192.168.12.0/24 is directly connected, FastEthernet0/1
C    192.168.13.0/24 is directly connected, FastEthernet0/0
     10.0.0.0/24 is subnetted, 1 subnets
S       10.1.1.0 [1/0] via 192.168.13.3
D    192.168.23.0/24 [90/30720] via 192.168.12.2, 01:01:30, FastEthernet0/1
D EX 192.168.34.0/24 [170/30976] via 192.168.12.2, 01:01:29, FastEthernet0/1

R4#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

B    192.168.12.0/24 [200/30720] via 192.168.23.2, 01:00:35
     10.0.0.0/24 is subnetted, 1 subnets
C       10.1.1.0 is directly connected, FastEthernet0/1
B    192.168.23.0/24 [200/0] via 192.168.34.3, 01:00:40
C    192.168.34.0/24 is directly connected, FastEthernet0/0

lagapidis · February 22, 2022, 8:29am

Hello Kenneth

I labbed this one up with a slightly different topology than yours.

I was able to redistribute 1.1.1.1 from the OSPF domain to EIGRP, and then re-redistribute that into the BGP AS 1. I did this by simply using the redistribute eigrp 1 command in R2. Similarly in your topology, you should be able to redistribute all EIGRP routes in your R3 (including those learned via OSPF such as 192.168.13.0/24) via the redistribute eigrp command in R3.

However, keep in mind that in your case, even though R4 will learn about 192.168.13.0/24 from the redistribution of EIGRP into BGP, when packets with such a destination reach R3, the will be routed via the directly connected interface of F0/1.

I hope this has been helpful!

Laz

kent2612 · February 25, 2022, 11:06am

The issue here is with mutual redistribution between OSPF and EIGRP on R1, and BGP and EIGRP on R3, R4 is not seeing 192.168.13.0/24. Likewise R1 and R2 is not seeing 10.1.1.0/24 that R4 advertised.

lagapidis · February 28, 2022, 1:29pm

Hello Kenneth

I feel like I’m missing something . For me, it seems straightforward that if you enable mutual redistribution between OSPF and EIGRP on R1 and mutual redistribution between EIGRP and BGP on R3, then R4 will learn about the 192.168.13.0/24 subnet as in my example topology that I labbed up. Similarly, 10.1.1.0/24 should also appear in R4 (although I didn’t lab this particular scenario). I’m not clear as to why you’re not seeing this.

If I’m missing something, I apologize and ask that you indulge me and clarify what I am misunderstanding. It may also be helpful if you share your routing protocol commands on those routers in question. Hopefull in this way we’ll get to the bottom of the problem…

I hope this has been helpful!

Laz