OSPF neighbor relation of NE20(E) cannot be built and its reasons.
NE20/20E can be displayed and configured through command.
1. The interface does not enable OSPF protocol.
2. The physical layer and the link layer are probllematic.
3. The interface is defined as silient-interface.
4. The devices of both ports deny OSPF protocol packet or the intermediate device denies OSPF protocol packet .
5. The subnet mask of IP address of interconnected port is not consistent.
6. OSPF authentication type or authentication password of both ports is not consistent.
7. area id of both ports is not consistent.
8. The area type of interconnected interface (common, stub and NSSA) is not consistent.
9. The interface uses slave address to establish neighbor relation.
10. It does not define network type or designate neighbor relation inNBMA, Frame Relay and X.25.
11. It is short of broadcast in frame-relay (fr map ip), ATM (map ip) and dialer(dialer route ip) command.
OSPF of NE20/20E cannot be established. The problem can be checked through display ospf error or debug ospf.