Help with GRE

[Rudy9746]

Hello,

Sorry if this isn't the correct spot to post this, I'm new here and new to networking.

I'm trying to set up a GRE tunnel from my Edge to New Branch routers.

I keep getting the following error:

New_Branch(config-if)# %ADJ-5-PARENT: Midchain parent maintenance for IP midchain out of 10 65E900C0 - looped chain attempting to stack

%TUN-5-RECURDOWN: 10 temporarily disabled due to recursive routing

%LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel10, changed state to down

%DUAL-5-NBRCHANGE: IP-EIGRP 10: Neighbor 10.1.1.1 (Tunnel10) is down: interface down

My configs are as follows:

Edge Router

!

interface Tunnel10

ip address 10.1.1.1 255.255.255.252

mtu 1476

tunnel source GigabitEthernet0/0

tunnel destination 209.165.200.10

!

!

interface GigabitEthernet0/0

ip address 209.165.200.1 255.255.255.252

ip nat outside

duplex auto

speed auto

!

interface GigabitEthernet0/1

no ip address

duplex auto

speed auto

shutdown

!

interface GigabitEthernet0/2

no ip address

duplex auto

speed auto

shutdown

!

interface Serial0/0/0

ip address 10.10.10.2 255.255.255.252

ip nat inside

!

interface Serial0/0/1

no ip address

ip nat inside

clock rate 2000000

shutdown

!

interface Vlan1

no ip address

shutdown

!

router eigrp 10

redistribute static

network 10.10.10.0 0.0.0.3

network 10.10.10.4 0.0.0.3

network 10.1.1.0 0.0.0.3

!

router bgp 6500

bgp log-neighbor-changes

no synchronization

neighbor 209.165.200.2 remote-as 6501

network 209.165.200.0 mask 255.255.255.252

network 209.165.100.10 mask 255.255.255.255

!

ip nat inside source list 9 interface GigabitEthernet0/0 overload

ip nat inside source static 10.0.1.10 209.165.100.10

ip classless

ip route 0.0.0.0 0.0.0.0 GigabitEthernet0/0

!

ip flow-export version 9

!

!

access-list 9 permit 172.16.0.0 0.0.7.255

access-list 9 permit 192.168.0.0 0.0.15.255

access-list 9 permit 10.10.10.0 0.0.0.31

!

New Branch Router

!

interface Tunnel10

ip address 10.1.1.2 255.255.255.252

mtu 1476

tunnel source Serial0/0/0

tunnel destination 209.165.200.1

!

!

interface GigabitEthernet0/0

no ip address

duplex auto

speed auto

!

interface GigabitEthernet0/0.10

encapsulation dot1Q 10

ip address 172.16.0.1 255.255.255.0

!

interface GigabitEthernet0/0.20

encapsulation dot1Q 20

ip address 172.16.4.1 255.255.255.0

!

interface GigabitEthernet0/1

no ip address

duplex auto

speed auto

shutdown

!

interface GigabitEthernet0/2

no ip address

duplex auto

speed auto

shutdown

!

interface Serial0/0/0

ip address 209.165.200.10 255.255.255.252

!

interface Serial0/0/1

no ip address

clock rate 2000000

shutdown

!

interface Vlan1

no ip address

shutdown

!

router eigrp 10

passive-interface GigabitEthernet0/0

network 10.1.1.0 0.0.0.3

network 172.16.0.0 0.0.3.255

network 172.16.4.0 0.0.1.255

!

router bgp 6503

bgp log-neighbor-changes

no synchronization

neighbor 209.165.200.9 remote-as 6502

network 209.165.200.8 mask 255.255.255.252

!

I have read other articles on this, and I still can't seem to figure out how to fix it.

Thanks in advance!

[luis_cordova]

Hi @Rudy9746 

I have a suspicion of the cause of the problem.

Edge Router

router eigrp 10

no redistribute static

HQ Router

ip route 0.0.0.0 0.0.0.0 10.10.10.2

On occasion, redistribution causes problems with the GRE tunnel.

Try that.
In addition, you can compress your exercise (winzip) and attach it for testing.

Regards

[Rudy9746]

Thanks, but sadly this one requires Edge to redistribute the static route, so I can't remove it.

[Rudy9746]

I added the compressed packet tracer for testing.

[luis_cordova]

Hi @Rudy9746 

I have done tests and with the redistribution, the tunnel goes up and down.
On the other hand, without redistribution the tunnel is stable.
As the distribution is included within the routing protocol updates, these are also sent to the router on the other side of the tunnel, creating this tunnel flapping.

Regards

[Georg Pauwen]

Hello,

the tunnel is down due to recursive routing because you are advertising the tunnel network (and the tunnel destination) in EIGRP, which causes the router to reach the tunnel destination through the tunnel itself...

Remove:

network 10.1.1.0 0.0.0.3

from the EIGRP process...

[Rudy9746]

Thanks! I'll give that a try.

[Rudy9746]

This may be a total newbie question, but won't that prevent EIGRP from forming neighbor adjacencies across the tunnel?

[Georg Pauwen]

Hello,

I have opened your project, but there is no tunnel on the branch (or any other except the edge) router...?

[Rudy9746]

Sorry @Georg Pauwen ! I posted the wrong file. Try again, it should be right now.

[luisca12_]

Hi George, I'm doing a similar exercise but with OSPF, and the guy from the original post asked this "This may be a total newbie question, but won't that prevent EIGRP from forming neighbor adjacencies across the tunnel?" isn't that true or? I'm trying to resolve the same problem.

[Rudy9746 · Accepted solution]

@luis_cordova @Georg Pauwen I reached out to my instructor a while ago and just now heard back from him, he gave me the OK to do static default routes on the routers rather than use redistribute. Apparently the instructions given for the assignment need to be updated. Sorry for the anticlimactic ending, but than you tons for trying to help!

[luis_cordova]

HI @Rudy9746 

I'm glad it could be solved.
I tell you that I am an instructor too and this problem with the tunnel had happened to me before.
Therefore, I indicated in my first post that the problem was generated by redistribution.

Regards

[Georg Pauwen]

Hello,

I have attached the revised project file.

Network 10.1.1.0 0.0.0.3 has been removed from both EIGRP processes, and on the branch router,a default route out serial0/0/0 has been added....