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Webcast-Catalyst9k
New Member

GRE tunnel goes up/down

Hi All,

Please, look at the excerpt below and suggest what might be the reason.  I do not know how to solve the problem.

Branch(config-if)#

*Sep 16 10:05:15.346: %LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel0, changed state to up

Branch(config-if)#

*Sep 16 10:05:16.366: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 172.16.100.1 (Tunnel0) is up: new adjacency

Branch(config-if)#

*Sep 16 10:05:24.350: %TUN-5-RECURDOWN: Tunnel0 temporarily disabled due to recursive routing

*Sep 16 10:05:25.346: %LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel0, changed state to down

*Sep 16 10:05:25.410: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 172.16.100.1 (Tunnel0) is down: interface down

Branch(config-if)#

Branch(config-if)#

*Sep 16 10:05:15.346: %LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel0, changed state to up

Branch(config-if)#

*Sep 16 10:05:16.366: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 172.16.100.1 (Tunnel0) is up: new adjacency

Branch(config-if)#

*Sep 16 10:05:24.350: %TUN-5-RECURDOWN: Tunnel0 temporarily disabled due to recursive routing

*Sep 16 10:05:25.346: %LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel0, changed state to down

*Sep 16 10:05:25.410: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 172.16.100.1 (Tunnel0) is down: interface down

Branch(config-if)#

Thanks for your help.

4 REPLIES
Purple

GRE tunnel goes up/down

HI,

*Sep 16 10:05:24.350: %TUN-5-RECURDOWN: Tunnel0 temporarily disabled due to recursive routing

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094690.shtml

Regards

Alain

Don't forget to rate helpful posts.

Don't forget to rate helpful posts.
New Member

GRE tunnel goes up/down

Thank you Sir!  Apology for the delayed response.  I wanted to be sure that I understood the steps to take.  The problem has been resolved based on the link you recommended.

Hi Alain

Hi Alain

I took a look on the subject, and I have a question, when we will configure the static route 

it will solve the problem for sure, but the we will not use the routing protocol EIGRP, so I can't see why we will use this solution whitout knowing the source problem for the flapping of th tunnel interface!!!

Thanks

Hall of Fame Super Gold

I do not understand how you

I do not understand how you believe that configuring a static route for the tunnel destination address means that you will not use the routing protocol. We would use the routing protocol to advertise our subnets to the remote peer and use the routing protocol to learn the subnets from the remote peer. But if the tunnel destination address is learned by the routing protocol then it produces the recursive routing problem, which was the case in the original post. While there are other potential solutions the most common solution to the problem is a static route for the destination. Then you can use the dynamic routing protocol for the other subnets.

HTH

Rick

[edit] Clearly the source of the flapping was recursive routing and recursive routing happens when the tunnel destination address appears to be reached through the tunnel. Having the tunnel destination address included in the dynamic routing protocol is the most common source of this problem.

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