https://support.huawei.com/enterprise/zh/doc/EDOC1100112408/952c65c0?idPath=24030814|21432787|23708834|250680707

OSPF的过滤，别人的总结：

https://forum.huawei.com/enterprise/en/ospf-route-filtering/thread/483043-861

Hello everyone,

OSPF route filtering is divided into two aspects: One is pure routing entries, and the other is LSA routing based on SPF calculation. Therefore, the most thorough filtering is to filter LSAs. In the following six types of filtering, only the first type of filter-policy import is used to filter routes, and the latter is used to filter LSAs.

OSPF filtering

1. Filter-policy import (configured in the OSPF process)

This command can only suppress the generation of routes. Therefore, you can filter the routes regardless of the routes to be generated. The LSA flooding, however, cannot be prevented.

[R3-ospf-1]undo filter-policy ip-prefix 1 import

2. Filter-policy export (configured in the OSPF process)

This command is used to filter the ASE/NSSA on the ASBR. This command is used to suppress the generation of LSAs. Once the LSA is generated, this command is useless. In addition, this command can be configured only on the ASBR and is not used on other routes, the LSA has been generated.

[R1-ospf-1]undo filter-policy ip-prefix 1 export

3. Asbr-summary not-advertise (configured in the OSPF process)

This command is used to filter the ASE/NSSA generated by itself on the ASBR. In fact, the is suppressed. The local LSDB does not contain the related LSA.

[R1-ospf-1]undo asbr-summary 11.11.11.11 255.255.255.255

4. Filter import/export (configured in the region)

This command is used to filter the three types of LSAs on an ABR, regardless of whether the three types of LSAs are generated by the ABR or received by other routers. It is invalid for Type 5 LSAs.

[R3-ospf-1-area-0.0.0.0]undo filter ip-prefix 1 export

[R3-ospf-1-area-0.0.0.200]undo filter ip-prefix 2 import

5. Abr-summary not-advertise (configured in the region)

This command is used to filter the three types of LSAs on an ABR. Only the three types of LSAs generated by the ABR can be filtered. The three types of LSAs received from other devices cannot be filtered. (The reason is that this command is an aggregation command. Currently, the aggregation commands of the VRP and IOS only aggregate the routes of the local area but not the inter-area routes. Therefore, the abr-summary not-advertise command is used to filter the intra-area routes of the local area.)

6. Ospf filter-lsa-out (configured on the interface.)

You can filter out any type of LSA. After the configuration is complete, you need to clear the process.

That is all I want to share with you! Thank you!