Troubleshooting step: OSPF neighbor getting stuck in a loading state

[knaveenkumar]

Description	This article describes troubleshooting steps to solve OSPF getting stuck in a loading state.
Scope	Any supported FortiGate version.
Solution	In the loading state, LS request packets are sent to request the more recent instance of an LSA that has not been received during the exchange process. In the above Figure, Router1 is in the loading state and is sending ls request packets to receive a more recent instance of an LSA. Problem: OSPF neighbor stuck in loading state. The most common causes of this problem are as follows: Mismatched MTU. Corrected link-state request packet. When the OSPF database is full the LSA limit is exceeded. For this, it is necessary to check the LSA is limited. solution. ======== - Adjust the MTU. Reset the IPsec /OSPF neighbor (do not do it if its Advpn setup) and during the downtime reset the IPsec /OSPF neighbor on the spoke device and check. - Configure the stub area and the HUB advertises the default route to this spoke. - Summarize the network in the Hub (ABR OR ASBR) and send the route to the spoke. - Once spoke will receive summarize route and default route from Hub it will reduce the OSPF database. Run the below commands and Check the status: #  get router info OSPF interface #  get router info OSPF neighbor #  get router info ospf database brief