Hi, Acee and Peter: I think you all misunderstood the intent of his scenario. The correct understanding are the followings: 1) When aggregate route is configured in the ABR, the specified detail route should be withdrawn. 2) ABR can withdraw the advertised LSA that describes the specific detail route, via premature mechanism(MaxAge or LSInfinity, the former is preferred according to RFC2328) 3) But, withdrawn such specific LSA doesn’t mean the corresponding detail route unreachable——This destination can be reached via the aggregate route advertised by ABR instead.
This is the original usage of LSInfinity defined in RFC2327. It should be expanded further. How to apply it in RFC8362 is another issue, as indicated my responses in another thread. In summary, again, we should constrain or depreciate the confusion usages of LSInfinity. Aijun Wang China Telecom > On Oct 13, 2022, at 18:07, Acee Lindem (acee) > <acee=40cisco....@dmarc.ietf.org> wrote: > > Hi Zhibo, > > On 10/13/22, 2:26 AM, "Lsr on behalf of Huzhibo" <lsr-boun...@ietf.org on > behalf of huzhibo=40huawei....@dmarc.ietf.org> wrote: > > Hi LSR: > > LSInfinity > The metric value indicating that the destination described by an > LSA is unreachable. Used in summary-LSAs and AS-external-LSAs > > I want to clarify the meaning of unreachable in LSifinity, > Assume that a node advertise specific route of 1.1.1.1/32, and an > aggregate route 1.1.0.0/16 is configured. > This node should premature aging of the 1.1.1.1/32 LSA. > If this node using LSInfinity metric instead of prematuring aging, route > 1.1.1.1/32 is still reachable. > Therefore, the "unreachable" described by LSifinity is not really > unreachable. > > If your OSPF implementation includes unreachable LSAs in the summary cost > computation, it is indeed broken. > > Thanks, > Acee > > Thanks > Zhibo hu > >> -----Original Message----- >> From: Lsr [mailto:lsr-boun...@ietf.org] On Behalf Of Peter Psenak >> Sent: Wednesday, October 5, 2022 5:32 PM >> To: lsr@ietf.org >> Subject: [Lsr] RFC 8362 and LSInfinity >> >> Hi Folks, >> >> metric of LSInfinity (0xFFFFFF) has been defined in RFC2328: >> >> LSInfinity >> The metric value indicating that the destination described by an >> LSA is unreachable. Used in summary-LSAs and AS-external-LSAs >> as >> an alternative to premature aging (see Section 14.1). It is >> defined to be the 24-bit binary value of all ones: 0xffffff. >> >> RFC5340 inherited it from RFC2328: >> >> Appendix B. Architectural Constants >> >> Architectural constants for the OSPF protocol are defined in >> Appendix >> B of [OSPFV2]. The only difference for OSPF for IPv6 is that >> DefaultDestination is encoded as a prefix with length 0 (see >> Appendix A.4.1). >> >> Both RFC2328 and RFC5340 used 16 bits metric for intra-area prefix >> reachability, so the LSInfinity was not applicable for intra-area prefixes. >> >> RFC8362 defines 24-bit metric for all prefix reachability TLVs - >> Intra-Area-Prefix TLV, Inter-Area-Prefix TLV, External-Prefix TLV. >> Al _______________________________________________ Lsr mailing list Lsr@ietf.org https://www.ietf.org/mailman/listinfo/lsr
