OSPF and EIGRP running over the same WAN interfaces

[dabonilla]

Hi all,

I'm the new network administrator at my job, since most of the routers are CISCO devices, the network is running EIGRP at the CORE and Distribution.

As a requiriment, I need to change de EIGRP to implement OSPF.

We have 4 Nexus 7000s por CORE and DIST, at border we want to run both OSPF and EIGRP.

My question is,

which is the better approach to achieve my goal - eliminate EIGRP at the CORE and DIST.

What I want to do is:

1- Run OSFP over the same EIGRP WAN interfaces without announcing the LANs, only the WANs and a new Loopback interface which will be configured on each router.

DOUBT: Will Adjacencies be formed without affecting EIGRP neighborships? Will the CPE be hooked by the routing protocols?

But I'd like to know if there any better idea.

Any comment will be appreciated.

[Peter Paluch]

Hello,

1- Run OSFP over the same EIGRP WAN interfaces without announcing the LANs, only the WANs and a new Loopback interface which will be configured on each router.

You can do this, and running EIGRP and OSPF at the same time over the same interface will not impact their adjacencies: EIGRP neighbors will stay running just fine, and OSPF neighbors will come up.

But a migration of one routing protocol to another requires a good deal of planning. Can you post a simplified diagram of your network, showing where EIGRP currently runs and where OSPF is intended to run?

Best regards,
Peter

[paul driver]

Hello

your present eigrp will take precedence over ospf, So as Peter says the ospf adjuecnes will occur with no inpact on you network.( if you dont advertised your prefixs) that is.

If you do wish to advertised and test

I would suggest maniptilating the admindistances of eigrp  first so to capture any external routes from OSPF so theywont be readvetised into the new process (ospf)

router eigrp xxx
distance eigrp 90 109 ( receivng routes)
 

Rx#sh ip route ospf

Rx#sh ip route eigrp
D    2.0.0.0/8 [90/409600] via 10.1.12.2, 00:01:08, FastEthernet0/0
D    22.0.0.0/8 [90/409600] via 10.1.12.2, 00:01:08, FastEthernet0/0
D    222.0.0.0/8 [90/409600] via 10.1.12.2, 00:01:08, FastEthernet0/0
D EX 200.0.0.0/8 [109/409600] via 10.1.12.2, 00:01:08, FastEthernet0/0


to test ospf

router eigrp xxx
distance eigrp 111 111
 

Rx#sh ip route eigrp

Rx#sh ip route ospf
O    2.0.0.0/8 [110/11] via 10.1.12.2, 00:00:30, FastEthernet0/0
O    22.0.0.0/8 [110/11] via 10.1.12.2, 00:00:30, FastEthernet0/0
O    222.0.0.0/8 [110/11] via 10.1.12.2, 00:00:30, FastEthernet0/0
O E2 200.0.0.0/8 [110/20] via 10.1.12.2, 00:00:30, FastEthernet0/0

res

Paul