GRE Tunnel Recursive Routing error

GRE Tunnel Recursive Routing error

GRE

in the topology above I have created GRE Tunnel between HQ and Branch.
 For now it works fine, because the tunnel destination is not the IP address of the tunnel interface on the other end (the tunnel destination is the physical interface on the other end) .However if I  Traceroute from HQ to Branch or the other way around, then the traffic will go through ISP.


If ,for instance, on HQ I use Tunnel destination 192.168.13.3 (which is the  Branch Tunnel interface IP address), then the tunnel will collapse.

So, I do not know what would be the purpose of the GRE tunnel if traffic does not go through the Tunnel
 



ISP#sh run 
Building configuration...

Current configuration : 1790 bytes
!
! Last configuration change at 22:26:13 CET Sun Feb 25 2018
!
version 15.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname ISP
!
boot-start-marker
boot-end-marker
!
aqm-register-fnf
!
!
no aaa new-model
clock timezone CET 1 0
mmi polling-interval 60
no mmi auto-configure
no mmi pvc
mmi snmp-timeout 180
!
!
!
!
!
!


!
!
!
!
ip cef
no ipv6 cef
!
multilink bundle-name authenticated
!
!
!
!
!
!
!         
!
!
redundancy
!
!
! 
!
!
!
!
!
!
!
!
!
!
!
!
interface Ethernet0/0
 ip address 192.168.12.1 255.255.255.0
!
interface Ethernet0/1
 ip address 192.168.23.1 255.255.255.0
!
interface Ethernet0/2
 no ip address
 shutdown
!
interface Ethernet0/3
 no ip address
 shutdown
!
interface Ethernet1/0
 no ip address
 shutdown
!
interface Ethernet1/1
 no ip address
 shutdown
!
interface Ethernet1/2
 no ip address
 shutdown
!
interface Ethernet1/3
 no ip address
 shutdown
!
interface Serial2/0
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial2/1
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial2/2
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial2/3
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial3/0
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial3/1
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial3/2
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial3/3
 no ip address
 shutdown
 serial restart-delay 0
!
router rip
 version 2
 network 192.168.12.0
 network 192.168.23.0
 no auto-summary
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
!
!
!
!
control-plane
!
!
!
!
!
!
!
!
line con 0
 logging synchronous
line aux 0
line vty 0 4
 login
 transport input none
!
!
end

ISP#

Open in new window


HQ#sh run 
Building configuration...

Current configuration : 1967 bytes
!
! Last configuration change at 22:40:16 CET Sun Feb 25 2018
!
version 15.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname HQ
!
boot-start-marker
boot-end-marker
!
aqm-register-fnf
!
!
no aaa new-model
clock timezone CET 1 0
mmi polling-interval 60
no mmi auto-configure
no mmi pvc
mmi snmp-timeout 180
!
!
!
!
!
!


!
!
!
!
ip cef
no ipv6 cef
!
multilink bundle-name authenticated
!
!
!
!
!
!
!         
!
!
redundancy
!
!
! 
!
!
!
!
!
!
!
!
!
!
!
!
interface Loopback0
 ip address 1.1.1.1 255.255.255.255
!
interface Tunnel1
 ip address 192.168.13.1 255.255.255.0
 tunnel source Loopback0
 tunnel destination 192.168.23.3
!
interface Ethernet0/0
 ip address 192.168.12.2 255.255.255.0
!
interface Ethernet0/1
 no ip address
 shutdown
!
interface Ethernet0/2
 no ip address
 shutdown
!
interface Ethernet0/3
 no ip address
 shutdown
!
interface Ethernet1/0
 no ip address
 shutdown
!
interface Ethernet1/1
 no ip address
 shutdown
!
interface Ethernet1/2
 no ip address
 shutdown
!
interface Ethernet1/3
 no ip address
 shutdown
!
interface Serial2/0
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial2/1
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial2/2
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial2/3
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial3/0
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial3/1
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial3/2
 no ip address
 shutdown
 serial restart-delay 0
!         
interface Serial3/3
 no ip address
 shutdown
 serial restart-delay 0
!
router rip
 version 2
 network 1.0.0.0
 network 192.168.12.0
 network 192.168.13.0
 no auto-summary
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
!
!
!
!
control-plane
!         
!
!
!
!
!
!
!
line con 0
 logging synchronous
line aux 0
line vty 0 4
 login
 transport input none
!
!
end

HQ#

Open in new window


Branch#sh run 
Building configuration...

Current configuration : 1971 bytes
!
! Last configuration change at 22:40:52 CET Sun Feb 25 2018
!
version 15.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Branch
!
boot-start-marker
boot-end-marker
!
aqm-register-fnf
!
!
no aaa new-model
clock timezone CET 1 0
mmi polling-interval 60
no mmi auto-configure
no mmi pvc
mmi snmp-timeout 180
!
!
!
!
!
!


!
!
!
!
ip cef
no ipv6 cef
!
multilink bundle-name authenticated
!
!
!
!
!
!
!         
!
!
redundancy
!
!
! 
!
!
!
!
!
!
!
!
!
!
!
!
interface Loopback0
 ip address 3.3.3.3 255.255.255.255
!
interface Tunnel1
 ip address 192.168.13.3 255.255.255.0
 tunnel source Loopback0
 tunnel destination 192.168.12.2
!
interface Ethernet0/0
 ip address 192.168.23.3 255.255.255.0
!
interface Ethernet0/1
 no ip address
 shutdown
!
interface Ethernet0/2
 no ip address
 shutdown
!
interface Ethernet0/3
 no ip address
 shutdown
!
interface Ethernet1/0
 no ip address
 shutdown
!
interface Ethernet1/1
 no ip address
 shutdown
!
interface Ethernet1/2
 no ip address
 shutdown
!
interface Ethernet1/3
 no ip address
 shutdown
!
interface Serial2/0
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial2/1
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial2/2
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial2/3
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial3/0
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial3/1
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial3/2
 no ip address
 shutdown
 serial restart-delay 0
!         
interface Serial3/3
 no ip address
 shutdown
 serial restart-delay 0
!
router rip
 version 2
 network 3.0.0.0
 network 192.168.13.0
 network 192.168.23.0
 no auto-summary
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
!
!
!
!
control-plane
!         
!
!
!
!
!
!
!
line con 0
 logging synchronous
line aux 0
line vty 0 4
 login
 transport input none
!
!
end

Branch#

Open in new window

jskfanAsked:
Who is Participating?
 
JustInCaseConnect With a Mentor Commented:
There are few problems with current configurations.
- ISP, generally, does not participate in routing
- traffic need to be forwarded into tunnel to be tunneled (static or dynamic routing)
- recursive loop happens when tunnel end point is advertised through tunnel which will lead tunnel to collapse (routing instead to point in direction of WAN interface to reach other tunnel end is pointing to tunnel itself (root cause of recursive routing problem))
0
 
jskfanAuthor Commented:
Thank you..
I will redo the LAB sometime in the Future and see how it is supposed to work
0
 
JustInCaseCommented:
You're welcome.
0
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