Destination Host Unreachable issue with GRE static routing

[JeViCo]

Hi, i'm a student at a college and i'm trying to figure out how GRE works. I split the network into two segments (192.168.1.x on the left and 192.168.2.x on the right) and set up GRE tunnel on Router0 and Router1. It works great when Router0 and Router1 are connected directly (with corresponding static routing). I tried to add another router in between to route GRE traffic and keep getting "unreachable host" issue. Here's my PKT file: https://www.dropbox.com/s/ord7qk52kguzgoz/lab2.1.pkt

After couple of hours of searching i've managed to find similar architecture but with different router model and it works perfectly for some reason. I modified it a little bit to match ip addresses from my PKT file and it still works. Here's the similar one: https://www.dropbox.com/s/cv0lhf4sbgvthy1/sample.pkt

I have no idea what's going on here

[MHM Cisco World]

before the add of router the two GRE router head was direct connect after add router they are not 
so you need static route in each of GRE router head toward the destination of GRE tunnel 
keep all your config as it except add 

ip route 0.0.0.0 0.0.0.0 <next-hop> 

in both routers

[paul driver]

Hello

For Rtr 0-1 to form a GTE tunnel then the source/destination of the tunnel need to be reachable between rtrs 0-2
so in your topology

rtrs 0-2
router rip
no auto-summary
ver 2
network 172.16.1.0

rtr 0
int tun 1
tunnel source gig0/0
tunnel destination 172.16.2.1
ip address 10.10.10.1 255.255.255.252

ip route 192.168.2 0 255.255.255.0 tunnel 1 10.10.10.2

rtr1
int tun 1
tunnel source gig0/0
tunnel destination 172.16.1.1
ip address 10.10.10.2 255.255.255.252

ip route 192.168.1 0 255.255.255.0 tunnel 1 10.10.10.1

[Flavio Miranda]

Hello,

GRE is pretty simple to setup.

 I made some small fix on your file and it is working. Compare devices config with the file you have saved and see where you mistaken.

[JeViCo · Accepted solution]

My "Destination host unreachable" problem was solved with the following steps:

1. Type command in Router0 to forward traffic to Router2 if no routes found

ip route 0.0.0.0 0.0.0.0 172.16.1.2

2. Type command in Router1 to forward traffic to Router2 if no routes found

ip route 0.0.0.0 0.0.0.0 172.16.2.2

3. Clear the routing table (just in case)

clear ip route *

4. Save changes and reload Router0 and Router1
It's also recommended to update Cisco Packet Tracer to the latest version