NE80E and NE40 are in OSPF area0; NE80E is connected to external network 1, and NE40 is connected to external network 2. Configure OSPF filter for NE80E and NE40 to reference some external routes.
The problem is that NE40 and NE80E cannot reference the external routes upon completion of configuring OSPF filter.
Add a rule of permit parallel to the one of deny into ip-prefix policy, and the filter can take effect well; some relevant routes are blocked. It is known that a rule of permit is required if the deny rule is configured in ip-prefix so that other IP prefixes will not be blocked.
ip ip-prefix 1 index 10 deny 18.104.22.168 32 greater-equal 32 less-equal 32
ip ip-prefix 1 index 20 permit 0.0.0.0 0 less-equal 32
Before being configured with filter, NE80E and NE40 can reference external routes to OSPF. When NE40 is configured with filter for inbound direction, the OSPF routing table of NE40 is not advertised to the IP routing table; when NE80E is configured with filter for outbound direction, all OSPF routes in routing table of NE40 will be blocked. However, the ip-prefix policy is only set to denying a piece of route prefix. Check the OSPF state of two devices, and it is normal. The policy configuration is suspicious of problematic.