OSPF Adjchg error, adj-5-parent error, recursive routing error in PT

[George Vanyan]

Basically, I have created a GRE tunnel

I'd put Packet Tracer file, but the discussion won't accept the format

these are the networks

OSPF 10
area 0

GRE tunnel
172.16.100.0 /30

CS1-R1 net
192.168.1.0 /30

R1-ISP net
1.1.1.0 /30

R2-ISP net
1.1.1.4 /30

R2-CS2
192.168.2.0 /30

The errors started randomly 10-15 minutes after finalizing the setup 

you can check everything in the command log. There is a chance I am missing something, a newbie yet

these are the errors from R1

00:20:10: %OSPF-5-ADJCHG: Process 10, Nbr 5.5.5.5 on Tunnel1 from LOADING to FULL, Loading Done

00:20:50: %OSPF-5-ADJCHG: Process 10, Nbr 5.5.5.5 on Tunnel1 from FULL to DOWN, Neighbor Down: Dead timer expired

00:20:50: %OSPF-5-ADJCHG: Process 10, Nbr 5.5.5.5 on Tunnel1 from FULL to DOWN, Neighbor Down: Interface down or detached

Error from R2: 

03:20:53: %OSPF-5-ADJCHG: Process 10, Nbr 4.4.4.4 on Tunnel1 from LOADING to FULL, Loading Done

%ADJ-5-PARENT: Midchain parent maintenance for IP midchain out of 1 65E900C0 - looped chain attempting to stack

%TUN-5-RECURDOWN: 1 temporarily disabled due to recursive routing

%LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel1, changed state to down

%ADJ-5-PARENT: Midchain parent maintenance for IP midchain out of 1 65E900C0 - looped chain attempting to stack

%TUN-5-RECURDOWN: 1 temporarily disabled due to recursive routing

03:21:03: %OSPF-5-ADJCHG: Process 10, Nbr 4.4.4.4 on Tunnel1 from FULL to DOWN, Neighbor Down: Interface down or detached

[Harold Ritter]

Hi @George Vanyan ,

The issue is that the tunnel destination on R1 and R2 is being learnt via ospf and that creates a loop. You need to configure a static route on R1 and R2 for the tunnel destination.

R1:

ip route 1.1.1.6 255.255.255.255 1.1.1.1

R2:

ip route 1.1.1.2 255.255.255.255 1.1.1.5

This will take care of the loop.

Regards,

[MHM Cisco World]

ip route 0.0.0.0 0.0.0.0 1.1.1.1 111
Remove this ip route 172.16.100.2 255.255.255.255 GigabitEthernet0/0/0 
Remove this ip route 172.16.100.2 255.255.255.255 1.1.1.1 

[MHM Cisco World]

ip route 0.0.0.0 0.0.0.0 1.1.1.5 111
Remove this ip route 172.16.100.1 255.255.255.255 GigabitEthernet0/0/0 
Remove this ip route 172.16.100.1 255.255.255.255 1.1.1.5

[MHM Cisco World]

Also NAT with overload config' I dont get it' can you more elaborate more about this config.

[George Vanyan]

yeah, NAT overload enables PAT which was actually needed to block the traffic in the 10.10.1.0; 2.0; 3.0; 4.0; 5.0 and 6.0 networks from moving via ISP router. It should've made the traffic move via only the tunnel. that was the idea

[George Vanyan]

here's how it all looks

[George Vanyan]

both recommendations implemented - same error occurs

[MHM Cisco World]

Only remove  the NAT from both side  and check 

[George Vanyan]

no ip nat inside source list GRE interface

GigabitEthernet0/0/0 overload 

this one is needed, right

[MHM Cisco World]

Yes I think it NATing issue if you remove static route I mention before.

For recursive routing it happened when you run routing protocol in tunnel have AD better than routing protocol for tunnel source 

Here ospf ad=90 and default route ad=1

So I think it NATing issue.

How I know that I run one time lab for dmvpn the tunnel flapping when NAT is config.

So we need to exclude gre from NAT

Deny gre any any I think is need.

I am out now when back home I will check again.

[paul driver · Accepted solution]

Hello
You have recursive routing - the tunnel source/destinations are being learned through the tunnel itself, hence the error logging.
you need to negate advertising tunnel source/destination subnets via the tunnel

[paul driver]

apologies I see @Harold Ritter  has already provides a solution

[George Vanyan]

@Harold Ritter ' s solution did not work

[Harold Ritter]

@George Vanyan ,

Configuring the tunnel destination as a static route towards the ISP is a very commonly seen solution to ensure that you do not get into a loop. I am not sure why it didn't work for you.

Regards,