How to prefer EIGRP over OSPF

[roger perkin]

On our network we run OSPF, we have one office who run EIGRP

I have the 10.185.0.0 network which is in OSPF and lives out of R3

From SWW001 I want to make the path to 10.185.0.0 to go via SWS001

The remote site put a static route on SWS001

ip route 10.185.0.0 255.255.0.0 10.0.3.2

The hope was that it would get redistributed via EIGRP back into osp.

SWS001

router eigrp 1
redistribute connected
redistribute static metric 109 10 255 1 1500 The theory was that this should be better than ospf?
network 10.0.1.2 0.0.0.0
auto-summary
eigrp stub connected static summary redistributed  What is this line doing?

SWW001

SWW001#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

     10.0.0.0/8 is variably subnetted, 4 subnets, 2 masks
C       10.0.2.0/24 is directly connected, FastEthernet1/0
D EX    10.0.3.0/24 [170/30720] via 10.0.1.2, 00:27:59, FastEthernet0/0
C       10.0.1.0/24 is directly connected, FastEthernet0/0
O       10.185.0.0/16 [110/2] via 10.0.2.2, 00:39:56, FastEthernet1/0 - The router is still preferring the OSPF route

I know I can resolve this with a static route on both switches, however the 10.185 network will change to different networks through the year and I want to be able to configure it so that the remote office just adds a static on SWS001 and this is redistributed into OSPF and beats OSPF

Thanks

Roger

[cadet alain]

Hi,

redistribute static metric 109 10 255 1 1500 The theory was that this should be better than ospf?

No as the AD of external EIGRP is 170 which is greater than OSPF which is 110.

Here you are just configuring the seed metric of the route when injected into EIGRP process and the metric is used only between routes to same prefix advertised by same protocol.

eigrp stub connected static summary redistributed  What is this line doing?

it is telling  EIGRP neighbours that this router is a STUB router and so must not be queried when a route goes active and that it must advertise connected,static and summary routes.

if you want  external eigrp to be more believable than OSPF then you can manipulate administrative distance of OSPF or of EIGRP on the router receiving the 2 routes but this will take effect for all prefixes not only the one you are resistributing now.

But if you don't link R5 to R4 you'll still have to forward through R3 anyway.

Regards.

Alain.

[Thotsaphon Lueangwattanaphong · Accepted solution]

Hi,

      If you want to prefer D*EX over O(Intra-area) for 10.185.0.0/16 network. You cannot modify AD for specific D*EX routes. You can modify AD for specific O routes.

For example

!

ip access standard R3-10.185.0.0/16

permit 10.185.0.0 0.0.255.255

!

router ospf 100

distance 180 <R3's router-ID> 0.0.0.0 R3-10.185.0.0/16

!

       Is that your full diagram? I didn't see the link to connect 10.185.0.0/16 from R5 point of view.

HTH,

Toshi

[roger perkin]

Thanks for that I will try it later. - after R5 there is a firewall which has the 10.185.0.0 network

Roger

[roger perkin]

Toshi,

Which router do you apply this config to?

[Thotsaphon Lueangwattanaphong]

Hi Roger,

    It's applied on SWW001.

Please get back to let us know how things work out.

Toshi

[roger perkin]

Toshi,

That works a treat - thank you!

Sh ip route on SWW001 before static route added on SWS001 - Notice Metric of OSPF route is 180

SWW001#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

     10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
C       10.0.2.0/24 is directly connected, FastEthernet1/0
C       10.0.1.0/24 is directly connected, FastEthernet0/0
O       10.185.0.0/16 [180/2] via 10.0.2.2, 00:00:26, FastEthernet1/0
SWW001#

Add static route on SWS001

ip route 10.185.0.0 255.255.0.0 10.0.3.2

SWW001#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

     10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
C       10.0.2.0/24 is directly connected, FastEthernet1/0
C       10.0.1.0/24 is directly connected, FastEthernet0/0
D EX    10.185.0.0/16 [170/25605120] via 10.0.1.2, 00:00:19, FastEthernet0/0 - EIGRP now wins with 170!
SWW001#

[Thotsaphon Lueangwattanaphong]

Hi,

   I'm glad that I can help.

Thanks

Toshi