Working GRE Tunnel goes down as soon as keepalive command is configured

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Hi,

i have this perculiar challenge...


Branches A and B have working gre tunnels to the head office thru Service Provider 1 and branches C and D have working GRE tunnels to Head Office thru Service Provider 2.


It was observed that after configuring "Keep alive 5 3" on all the tunnel interfaces on both head office and branches,

tunnel interfaces on Branches A and B went down but on branches C and D the tunnels were still up likewise all tunnels in head office were still up.


The interesting thing is tunnels from Branches A and B were passing traffic until the keep alive statement 5 3 was configured and the tunnel goes down as "interface up, line protocol down".


Is there anyway i can work around this as the bank wishes to have multiple links thru different service providers links and gre tunnels associated with theses links on all branches with Eigrp protocol as routing protocol. My fear is that branches without keepalive statements will create an illusion of being up and available when the physical is down and hence Eigrp may attempt to push traffic across those links and packet drops will occur?


How do i get the gre tunnels on branches A and B to work with the keep alive statements?

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spremkumar Wed, 09/03/2008 - 20:37
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Hi


Can you paste the output of show run and show ip route here ?


regds



Richard Burts Thu, 09/04/2008 - 08:03
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Obiora


I am similar to Edwin in thinking that there may be some mismatch in configuring the GRE tunnels on A and B to the head office. The show run config would help us to analyze this.


As far as your concern that EIGRP might attempt to push traffic over a link that is physically down, you should not have a concern about this. EIGRP sends hello packets over the GRE tunnels. If the hello packets are not delivered and not recieved (which they would not be delivered or received if the physical was down) then EIGRP converges quickly and will not attempt to use the physical that is down.


HTH


Rick

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