Redistribution of EIGRP to OSPF on LAN

[fallegretti]

Hi all,

I am struggling to control the router that does redistribution in case of two routers setup to do redistribution on a LAN.

Very simple Topology, imagine a LAN 172.16.0.0/24, R1 172.16.0.1, R2 172.16.0.2, R3 172.16.0.3, R4 172.16.0.4 Backbone 192.168.1.1 connected to a different interface to R4.

R1 runs OSPF

R2 runs OPSF and EIGRP

R3 runs OPSF and EIGRP

R4 runs EIGRP and RIP

Backbone RIP

So a prefix is generated by Backbone and passed to R4 via RIP. R4 redistribute it into EIGRP.

R2 and R3 both redistribute it to OSPF, when that happens one of them will prefer the OSPF route as admin distance went from 170 to 110, but what makes the routers decide which of the two routers keeps the eigrp and which one does the redistribution?

Tried everything I could think of. Thanks

[Jon Marshall]

Why are you redistributing EIGRP to OSPF on R2 and R3 ?

Regardless of that, it will simply be a race condition ie. one of the routers will be the first to redistribute and so the other will receive as OSPF and so will not redistribute because the EIGRP route will not be in the routing table. 

Jon

[fallegretti]

Hi Jon,

I am redistributing on both for redundancy, what if the router (or any other components of the solution, switch, WAN circuits, etc) has a problem?

I thought it would be a race condition but no matter what sequence I try in terms of enabling the routing protocols, it is always R3 doing the redistribution and cannot understand why. I am running this in GNS3 btw, not sure if this has have anything to do with it.

Thanks

[Jon Marshall]

So even if you enable redistribution on R2 first it is still R3 that ends up doing the redistribution ?

Jon

[fallegretti]

yep, I know it does not make sense and was expecting the race condition as  you mentioned.

Have noot had to run more tests in the last few days, I have been busy with other deployments, will go through the whole thing again.