VTI interface issue

[MustphaBassim]

Hello Dears

I had setup an ipsec tunnel between two Fortigate Firewalls , the tunnel is UP i am trying to create VTI interface on them so i had added an ip address on both devices on tunnel interfaces but i could not get reachablity (point to point) between them

T1 10.126.0.1 (FG1)

T1 10.126.0.2 (FG2)

where T1 is the tunnel interface on both devices

Best Regards

[vsahu]

Hello,

Can you share the interface route and tunnel details from both devices? Also, you'll need to add the tunnel interface IP in the phase 2  traffic selector if you've configured some specific phase 2  traffic selector.

show system interface <Name>
get router info routing-table details x.x.x.x
diag vpn tunnel list
diag vpn ike gateway list
get vpn ipsec tunnel summary

[MustphaBassim]

Hello Dear
after adding them to selector , now the ping is ok but unable to perferom OSPF adjecancy to the end node,

[vsahu]

Hello,

Please follow the below guide and verify the OSPF configuration.
https://community.fortinet.com/t5/FortiGate/Technical-Tip-OSPF-with-IPSec-VPN-for-network-redundancy...

If the configuration is fine share the below output:

get router info ospf neighbor
get router info ospf status
get router info ospf interface

[MustphaBassim]

I think the issue is releated to OSPF authentication , so any debug commend could help me in order to see what is the issue with ospf adjecency ?

[vsahu]

diagnose ip router ospf all enable
diagnose ip router ospf level info
diagnose debug enable

You can use the above command to enable the debug, to disable the debug use
diag debug disable

https://community.fortinet.com/t5/FortiGate/Troubleshooting-tips-for-FortiOS-routing-RIP-OSPF-BGP-st...

[Toshi_Esumi]

Check interface MTU with a CLI

get router info ospf interface

 on both sides.
If not matching, either set a common interface MTU size manually or set mtu-ignore under ospf-interface config on both sides. You can do it either CLI or GUI (at least after 7.0).

Toshi