Unanswered Question
Feb 25th, 2008


I can use distance command in router for

EIGRP TO OSPF MICRATION .Kindly give some input or documentation for EIGRP TO OSPF MICRATION.

I have this problem too.
0 votes
  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 4 (2 ratings)
royalblues Tue, 02/26/2008 - 01:29

Basically you dont need to alter the distance if you are planning to migrate from EIGRP to OSPF

EIGRP administrative distance would anyway be less than OSPF and hence your router wil lalways prefer those routes (Be cautious on the external routes though)

After the new protocol learns the network topology and all the routes, migration can be done by increasing the AD of EIGRP to be greater than OSPF.



CSCO10320953 Tue, 02/26/2008 - 20:55

Thanks.But I need ospf protocol.If administrative distance is not changing ,then the router will take the eigrp...is it correct or not

vaisharm Tue, 02/26/2008 - 21:29

Yes, if the same networks are being learnt by EIGRP and OSPF then EIGRP learnt routes would be used. However, do keep in mind that external eigrp routes have a higer AD (170) then OSPF (110)



CSCO10320953 Wed, 02/27/2008 - 04:48

Hi Shivlu/all,

10 location eigrp is running.I need to micrate permanently ospf.So I dont use route tagging.Using Distance command can achive this.....

These are the steps and confirm the same

Change Default AD of OSPF to 200 or above ( ie Higher that AD of External EIGRP)

DO NOT distribute between EIGRP & OSPF

DO NOT distribute static routes to OSPF

Ensure NO OSPF route is installed in the Routing table

ENSURE “IP-OSPF-DATABASE” lists all the Networks for respective RO

Verify OSPF convergence for all Routers in an area & then change AD of EIGRP in those RO to 255- this causes EIGRP routes to disappear & OSPF routes to be installed in Routing table of Core Router

Confirm reachability of all branches in the RO & ensure stability of OSPF area

Subsequently migrate remaining ROs

Finally after all ROs are migrated to OSPF, Change AD of EIGRP in Core router to 255 and AD of OSPF to its default ( 110)

Ensure Routing table in Core router is populated by OSPF for all Networks

SHUT / REMOVE EIGRP configuration in all routers.

royalblues Wed, 02/27/2008 - 04:59

Looks good to me

I would prefer changing the EIGRP AD to 254 rather than 255. This way any routes not reachable through ospf would still be reachable through EIGRP.


Mohamed Sobair Tue, 02/26/2008 - 12:04


Just adding the following in replying to shivlu's post:

The tagging field could be implemented on the external routes, ie, ospf, it has a tag field in the LSA header as an option to tag external routes.




This Discussion