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Why we can't implement distribute-list at ospf out interface?

Q. why we can not implement distribute-list at ospf out interface ??? e.g -------int serial0/0-------(Router1)-----int serial0/1------ int serial0/0 running EIGRP1 int serial0/1 running OSPF1 redistribution between EIGRP1 and OSPF1 is done at Router1 now if want to deny some networks from OSPF domain into EIGRP Domain Router)# distribute-list10 out se0/0 (here10 is ACL number) OR Router)# distribute-list10 out ospf1 in above both cases command is rejected..... why it so???? while in EIGRP case the above command works smoothly..

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Question added by KARIM ZADA , System Administrator , ADECCO MIDDLE EAST
Date Posted: 2013/08/25
Osama Al Otoom
by Osama Al Otoom , Network information Security Manager , unicom group for telecommunication technology

EIGRP uses composite metric, where OSPF uses cost metric.

Because OSPF and EIGRP use different metrics for routing, you must assign metrics when redistributing.

 

Also use route-maps when you make the redistribution under the routing process instead of using ACL

 

 

For example:

#router ospf1

 redistribute eigrp1 metric90 subnets route-map ospf-to-eigrp

.

.

.

#route-map ospf-to-eigrp permit10 match ip address10

 

*where 10 is your ACL

Umesh Ashu
by Umesh Ashu , Corporate Trainer , Koenig-Solutions

you cant filter routes out of an interface in ospf, because OSPF is a link state routing protocol, it sends LSA's not Routing Updates, if you really want to filter routes, then filter LSA's which can be done at area level OR for a single router.

For single router, you have to deny routes before they can be added in routing table.

When ospf receive LSA's,  it run SPF algorithm on them to add routes in routing table, after this it checks for any ACL/ Prefix-list/ to filter routes, this is where you have to tell which routes should be denied/Permited.

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