Question : Using GRE Tunnel as leased line Backup

I have been trying to set this up in a lab environment to deploy in to the field. I have routers connected back to back with a serial interface. Head office Leased lines to 2 branches. I also have the internet connected to the ethernet interfaces. I've built the leased lines and I was able to bring up the GRE tunnels. I haven't applied any IPSEC yet.

Here's my issue, when I admin shut my serial interface going to the branch, the GRE tunnel over the internet also fails and goes to an up/down state. Why is this happening? Isn't the serial interface separate from a configured tunnel interface going over the internet?

Code Snippet:

         
           
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             Home-Office#sh run
Building configuration...
 
Current configuration : 2194 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Home-Office
!
boot-start-marker
boot-end-marker
!
logging buffered 4096 debugging
enable secret 5 $1$WAs2$KyrXVCTLSj8P9i8rAF6HB.
!
no aaa new-model
!
resource policy
!
!
!
ip cef
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
username admin password 0 oppor2nity
!
!
!
!
!
!
interface Tunnel101
 description backup tunnel to Backup
 ip address 192.168.0.1 255.255.255.0
 keepalive 3 2
 tunnel source Ethernet3/0
 tunnel destination 64.128.34.45
!
interface Tunnel102
 ip address 192.168.2.1 255.255.255.0
 keepalive 3 2
 tunnel source Ethernet3/0
 tunnel destination x.x.x.43
!
interface Loopback0
 no ip address
!
interface FastEthernet1/0
 ip address 10.1.100.1 255.255.255.0
 ip nat inside
 ip virtual-reassembly
 duplex auto
 speed auto
!
interface Serial2/0
 description to Branch 1
 ip address 172.16.0.1 255.255.255.252
 ip nat inside
 ip virtual-reassembly
 clock rate 128000
 no dce-terminal-timing-enable
!
interface Serial2/1
 description to Branch 2
 ip address 172.16.1.1 255.255.255.252
 ip nat inside
 ip virtual-reassembly
 shutdown
 clock rate 128000
 no dce-terminal-timing-enable
!
interface Serial2/2
 no ip address
 shutdown
 no dce-terminal-timing-enable
!
interface Serial2/3
 no ip address
 shutdown
 no dce-terminal-timing-enable
!
interface Ethernet3/0
 ip address x.x.x.106 255.255.255.240
 ip nat outside
 ip virtual-reassembly
 full-duplex
!
interface TokenRing3/0
 no ip address
 shutdown
 ring-speed 16
!
router eigrp 100
 redistribute static
 network 10.1.100.0 0.0.0.255
 network 172.16.0.0 0.0.0.3
 network 172.16.1.0 0.0.0.3
 no auto-summary
!
router rip
 network 192.168.0.0
!
ip http server
no ip http secure-server
ip route 0.0.0.0 0.0.0.0 x.x.x.97
ip route 10.1.101.0 255.255.255.0 192.168.0.2 100
!
!
ip nat inside source list 130 interface Ethernet3/0 overload
!
access-list 130 permit ip 10.1.0.0 0.0.255.255 any
access-list 130 permit ip 172.16.0.0 0.0.0.3 any
access-list 130 permit ip 172.16.1.0 0.0.0.3 any
!
!
!
control-plane
!
!
!
!
!
!
!
!
!
!
line con 0
line aux 0
line vty 0 4
 password oppor2nity
 login
!
!
end
 
Home-Office#
 
Home-Office#sh ip int b
Interface                  IP-Address      OK? Method Status                Protocol
FastEthernet1/0            10.1.100.1      YES manual up                    up
Serial2/0                  172.16.0.1      YES manual up                    up
Serial2/1                  172.16.1.1      YES manual administratively down down  <<< I shut this
Serial2/2                  unassigned      YES NVRAM  administratively down down
Serial2/3                  unassigned      YES NVRAM  administratively down down
Ethernet3/0                x.x.x.106     YES NVRAM  up                    up
TokenRing3/0               unassigned      YES NVRAM  administratively down down
NVI0                       unassigned      NO  unset  up                    up
Loopback0                  unassigned      YES unset  up                    up
Tunnel101                  192.168.0.1     YES manual up                    up
Tunnel102                  192.168.2.1     YES manual up                    down  <<<< This goes down
Home-Office#

           
         

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Question : Using GRE Tunnel as leased line Backup

Answer : Using GRE Tunnel as leased line Backup

under the "router eigrp", you should setup route-map for redistribute static to filter out 0.0.0.0 network. this is a typical issue for GRE tunnel.