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Community Member

Redistributing default route into OSPF area

Hi,

We have OSPF area 40 and we have also defined the following static route.

ip route 0.0.0.0 0.0.0.0 fastethernet0/1

ip route 10.20.30.0 255.255.255.0 10.20.40.1

People are not able to see 10.20.30.0 network from other side but after redistributing static route to OSPF area by the command "redistribute static subnets " .It works fine.

My concerns are will the default route get redistributed to OSPF area , If so will it introduce any loop in the routing ? OR should i remove

ip route 0.0.0.0 0.0.0.0 fastethernet0/1

Appreciate your reply on this.

Thanks in advance

Nambi

3 REPLIES
Community Member

Re: Redistributing default route into OSPF area

If I understand correctly you want redistribute only 10.20.30.0 static route to OSPF. If so, you can configure filter, e.g.

router ospf 40

redistribute static

distribute-list 10 out Serial0/0

access-list 10 deny 0.0.0.0

access-list 10 permit any

If you configure static default route in the other site it should take the precedence then OSPF route, so you don't have to change anythink, I guess.

Rafal

Community Member

Re: Redistributing default route into OSPF area

thank you for the comment.

Yes , We can achieve with access list to distribute only the require route info. But my doubt is what will happen if default route is redistributed to the OSPF area will it affect the OSPF routing table. If so is there any way apart from access-list as it may increase the CPU usage.

Please do proivde your comments.

Nambi

Silver

Re: Redistributing default route into OSPF area

OSPF does not automatically propagate a default route (gateway of last resort or network 0.0.0.0 0.0.0.0). So, theoritcally, network 0.0.0.0 0.0.0.0 would not be installed on neighbour's routing tables.

To enable the propagation of 0.0.0.0 0.0.0.0 route, use the "default-information originate" router ospf command.

In any case, the default route (0.0.0.0 0.0.0.0) will not introduce a routing loop as long as it is originating from a single router.

Hope that helps,

Mustafa

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