Hi Chao, On 8/11/16, 5:22 AM, "Chao Fu" <[email protected]> wrote:
>Hi Acee, > >If my understanding is correct, you said there is the topology that an >ABR receives one NSSA LSA and one ASE LSA with the same destination, cost >and non-zero forwarding address. It is right but when doing external >route calculation, one of it would be rejected according to 2.5.(3): > If the forwarding address is non-zero look up the forwarding > address in the routing table. For a Type-5 LSA the matching > routing table entry must specify an intra-area or inter-area > path through a Type-5 capable area. For a Type-7 LSA the > matching routing table entry must specify an intra-area path > through the LSA's originating NSSA. >Then the path to the forwarding address cannot be through a Type-5 >capable area and an NSSA area at the same time, which means one of them >would be ignored here and no chance to match rule (e). With this respect to this reasoning, your understanding is incorrect. If the FA path is via a intra-area NSSA route (which it would be for an NSSA ABR), then it would be pass the reachability test for both the NSSA-LSA and the AS-External LSA. Thanks, Acee > >At the same time, rule (e) is not only defined to check the mixture of >an ASE LSA and an NSSA LSA, and then it is possible to compare two ASE >LSAs or two NSSA LSAs. But the referenced text describes that no such two >NSSA LSAs exist because one of them should be flushed. Consequently, the >condition of rule (e) will never be matched and then it is a redundant >rule. > >If rule (e) is not valid, I guess it is better to record it somewhere, >otherwise some conformance testers always want to verify it, that is the >reason why I would like to report the errata. If my understanding on rule >(e) is wrong, please correct me and I will appreciate it very much. > >Thanks & best Regards, >Chao Fu > >-----Original Message----- >From: Acee Lindem (acee) [mailto:[email protected]] >Sent: Monday, August 08, 2016 19:15 >To: RFC Errata System <[email protected]>; [email protected]; >[email protected]; [email protected]; Alvaro Retana (aretana) ><[email protected]>; Abhay Roy (akr) <[email protected]> >Cc: Chao Fu <[email protected]>; [email protected] >Subject: Re: [Technical Errata Reported] RFC3101 (4767) > >This Errata should be rejected as it is easy to envision a topology where >an ABR for an NSSA receives an NSSA-LSA from an NSSA internal router and >an AS-Exernal-LSA from originating routers that do not receive each >others equivalent LSAs. Furthermore, even if this were not the case, the >referenced text refers to LSAs that are both NSSA-LSAs as opposed to a >mixture of an NSSA-LSA and an AS-External-LSA. > >Thanks, >Acee > >On 8/7/16, 11:50 PM, "RFC Errata System" <[email protected]> >wrote: > >>The following errata report has been submitted for RFC3101, "The OSPF >>Not-So-Stubby Area (NSSA) Option". >> >>-------------------------------------- >>You may review the report below and at: >>http://www.rfc-editor.org/errata_search.php?rfc=3101&eid=4767 >> >>-------------------------------------- >>Type: Technical >>Reported by: Chao Fu <[email protected]> >> >>Section: 2.5.(6).(e) >> >>Original Text >>------------- >> (e) If the current LSA is functionally the same as an >> installed LSA (i.e., same destination, cost and non-zero >> forwarding address) then apply the following priorities in >> deciding which LSA is preferred: >> >> 1. A Type-7 LSA with the P-bit set. >> >> 2. A Type-5 LSA. >> >> 3. The LSA with the higher router ID. >> >> [NSSA] >> >>Corrected Text >>-------------- >>NULL (it should be deleted because no LSAs would be compared here.) >> >>Notes >>----- >>If one LSA is Type-5 and the other is Type-7, one of them would be >>rejected at step (2.5.(3) ( please refer to OSPF mail list: >>https://mailarchive.ietf.org/arch/msg/ospf/KBoh5T75o-s7n_bL1knrc6uVlTs ). >>If both of them are Type-7 LSAs, one of them would be flushed according >>2.4: >> If two NSSA routers, both >> reachable from one another over the NSSA, originate functionally >> equivalent Type-7 LSAs (i.e., same destination, cost and non-zero >> forwarding address), then the router having the least preferred LSA >> should flush its LSA. >> >>As a result, rule (e) would never be applied and should be removed. >> >>Instructions: >>------------- >>This erratum is currently posted as "Reported". If necessary, please >>use "Reply All" to discuss whether it should be verified or rejected. >>When a decision is reached, the verifying party (IESG) can log in to >>change the status and edit the report, if necessary. >> >>-------------------------------------- >>RFC3101 (draft-ietf-ospf-nssa-update-11) >>-------------------------------------- >>Title : The OSPF Not-So-Stubby Area (NSSA) Option >>Publication Date : January 2003 >>Author(s) : P. Murphy >>Category : PROPOSED STANDARD >>Source : Open Shortest Path First IGP >>Area : Routing >>Stream : IETF >>Verifying Party : IESG >> > _______________________________________________ OSPF mailing list [email protected] https://www.ietf.org/mailman/listinfo/ospf
