The NE80E is dual-homed to two devices. One is an NE5000E, and the other is a device of the manufacturer J.
The networking is as follows:
NE5000E Device of the manufacturer J
Run the default-route-advertise command on the NE5000E to advertise the OSPF default route. The device of the manufacturer J also advertises the OSPF default route. The NE80E, however, has no default route to the NE5000E in its routing table.
1. Check the OSPF neighbor relationship on the NE5000E and the NE80E. You can view that the OSPF neighbor relationship is in the Full state.
2. Check the routing table on the NE5000E and find that there are default routes to the external network.
3. Check the OSPF LSDB on the NE80E. You can view that there is a default route advertised by the NE5000E in the LSDB. The default route, however, is not selected. Check the configuration and find that the cost of the default route advertised by the device of the manufacturer J is 0. The cost of the default route advertised by the NE5000E, however, is 1. It is confirmed that the problem occurs because the default routes advertised by the different devices have different costs.
4. Set the cost of the default OSPF route advertised by the NE5000E to 0. Then, the NE80E can learn two default routes.
1. The OSPF neighbor relationship is abnormal.
2. Because the NE5000E does not forcibly advertise the default route, it is possible that the NE5000E has no default route so that it cannot advertise the default route.
3. The default route is not preferred due to some causes.
When devices of different manufacturers are connected, ensure that they have consistent parameters.