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 Post subject: OSPF on FR
PostPosted: Wed May 23, 2012 11:09 am 
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Hi.

I faced with an issue with FR/OSPF. my topology which shows VCs between routers is like this:

R1--------------R2
|----------------|
|----------------|
|----------------|
R4--------------R3

as you see there is no direct VC between R1 and R3. I used the physical serial interfaces on routers with inversARP enabled and set the OSPF network type to "point-to-multipoint" on all routers. R1 has loopback too on it. I expected that R3 should not be able to ping R1's loopback interface, because I did not setup any VC between R1 and R3 and even did not configure any static mapping. but R3 is able to ping R1's loop without any FR mapping configured or automatically know. so what is the cause of this?

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 Post subject: Re: OSPF on FR
PostPosted: Wed May 23, 2012 11:17 am 
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I'll give you a hint. Check your routing table and look at the nexthop.

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 Post subject: Re: OSPF on FR
PostPosted: Wed May 23, 2012 11:27 am 
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At the same time, you might want to investigate what setting 'point-to-multipoint' changes in the OSPF world ;)

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 Post subject: Re: OSPF on FR
PostPosted: Wed May 23, 2012 12:18 pm 
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Location: Ankara, turkey
reaper wrote:
I'll give you a hint. Check your routing table and look at the nexthop.


now I understand the issue! when we use "point-to-multipoint" network type, despite usual bevavior of FR, the next hop is changed. in this scenario R1 has 2 direct VCs to R2 and R4, but not R3. but with "point-to-multipoint" network type, when R1 sends packet to R4 through R2 or R3, the intermediate routers (R2 and/or R3) change the next-hop address and we will not have to configure static mappings on R3. tnx man ;)

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