There are several things to be satisfied before OSPF can establish its full adjacency. These are Area-ID, Stub-Flags, Interface-Type, Timers, Authentication, and MTU. These attributes must match to the other peering.
Let’s say that you have a scenario to create Q-in-Q which requires you to alter the default MTU to 1504 using system mtu 1504. The verification also shows that your system MTU is indeed 1504.
SWITCH-3560#sh system mtu System MTU size is 1504 bytes System Jumbo MTU size is 1504 bytes Routing MTU size is 1500 bytes