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so easy to loop ?

 
 
Yannick CHAMPS
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      08-06-2004
Hi,

2 routers running ospf over wan.
Router A redistribute a static route pointing to router B.
Router B get this ospf update and install a route pointing back to router A.
Easy loop created !
Is there no loop prevention mecanism ?

Yannick.
 
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JNCIP#0136
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      08-06-2004
Yes, that can easily happen if the next-hop of static route is NOT covered
by "network" statement
on Router A and then Router A creates LSA Type 5 with forwarding address
0.0.0.0 (means self).
Router B accepts this LSA and installs OSPF route with next-hop pointing to
Router A assuming
the AD of this route is most preferred.
Make sure You always specify OSPF network with correct wildcard mask and/or
double-check and redefine
AD on Router B.
Or get rid of static routes altogether
HTH,
Cheers
Alex

"Yannick CHAMPS" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) om...
> Hi,
>
> 2 routers running ospf over wan.
> Router A redistribute a static route pointing to router B.
> Router B get this ospf update and install a route pointing back to router

A.
> Easy loop created !
> Is there no loop prevention mecanism ?
>
> Yannick.



 
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Martijn
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      08-06-2004
http://www.velocityreviews.com/forums/(E-Mail Removed) (Yannick CHAMPS) wrote in message news:<(E-Mail Removed). com>...
> Hi,
>
> 2 routers running ospf over wan.
> Router A redistribute a static route pointing to router B.
> Router B get this ospf update and install a route pointing back to router A.
> Easy loop created !
> Is there no loop prevention mecanism ?
>
> Yannick.


Yannick,

If the static route on router A is pointing to a subnet directly
connected to router B, then there should be no loop since the metric
for a directly connected networks is lower. The only exception is when
the subnetmask configured in the static route is smaller ("most
specific route").

Regards, Martijn
 
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