Recursive routing

[yoram12345]

Hi all  ,

I have a setup in my lab as attached in the drawing.

I was expecting to get recursive routing problem - as i used the same static route destination as the destination of the gre tunnel destination,

however i did not get any problem and the tunnel was not flapping.

Any suggestions ?

BR,

Yoram

[donlindsay70]

R1 and r4 need to run ospf and learn the route to the tunnel destinations dynamically. So you need to advertise the connected networks on both R1 and r4 into the ospf process and confirm that R1 and r4 have routes to each other.

When the tunnel comes up, then the route to the tunnel destination endpoints will be via the tunnel due to the lower cost. You will then get recursive routing messages in your router console logs. You would normally use either static routes or inbound route filtering for the destination endpoints to avoid recursive routing.

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[yoram12345]

hi,

My setup is as attached as i simulated my customer's scenario.

OSPF exists only between R2 and R3 !

The rest R1 and R4 uses static routes.

I have ping between R1 and R4 .

The question is whether i should expect recursive routing in this exact scenario , where the OSPF is isolated only between

routers r2-r3 and not all the way r1-r2-r3-r4.

BR,

Yoram

[blau grana]

Hello Yoram,

I think there should not be problem with recursive routes.

I assume that static routes on both R1 and R4 point to physical interfaces. GRE tunnel should be established correctly, but to be sure, it would be helpful to post configuration of R1 and R4.

Best Regards

Please rate all helpful posts and close solved questions

[paul driver]

Hello,
to avoid recursive routing.

1) don't advertise the tunnel end points in routing protocol -use statics
2) if you are going to advertise the endpoints - provide filter/high metric / cost to make the less attractive

Res

paul


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