Jin, Sorry there was an omission in my previous post regarding
>RFC3101 2.5 Calculating type-7 as external routes (3) states: >Else if the destination is a Type-7 default route (destination > ID = DefaultDestination) and one of the following is true, > then do nothing with this LSA and consider the next in the > list: > o The calculating router is a border router and the LSA has > its P-bit clear. Appendix E describes a technique > whereby an NSSA border router installs a Type-7 default > LSA without propagating it. > > o The calculating router is a border router and is > suppressing the import of summary routes as Type-3 > summary-LSAs. > [NSSA] >Suppose user perform following steps in scenario(there is one ABR and ASBR >in NSSA area): >1)ASBR generate type-7 default route LSA to redistribute default route >from static route source. >2)In ABR,Create type 7 default route LSA via command like >"default-route-originate" for this NSSA area. >After step 2),the ABR calculation also should not consider type-7 default >route LSA redistribted by ASBRs? >Am I missing something?please correct me. The answer is still yes as stated in the previous post; but also all Type 7 default LSAs are ignored by NSSA ABRs when the no-summary option is configured. Whenever an NSSA ABR has no-summary configured, its default LSA has Type 3 so that it is preferred, in OSPF, by every one of the NSSA's non-ABR routers. The NSSA's ABR type 3 default LSA insures that the NSSA's non-ABRs must follow a summary default path through one of its ABRs when forwarding traffic to inter-area destinations. However, if one of the NSSA's non-ABRs has an installed non-OSPF default route, like a static default route, enabling no-summary on the NSSA border could adversely impact this non-ABR's ability to forward traffic to OSPF inter-area destinations. Pat _______________________________________________ OSPF mailing list [email protected] https://www1.ietf.org/mailman/listinfo/ospf
