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. 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. > Although it is silent about the LSInfinity as such, it is assumed that such > metric means unreachability for Inter-Area-Prefix TLV and External-Prefix > TLV. Given that Intra-Area-Prefix TLV now has 24 bits metric as well, it > would make sense to define the LSInfinity as unreachable for > Intra-Area-Prefix TLV as well. > > Would anyone object such a clarification in RFC8362? > > thanks, > Peter > > _______________________________________________ > Lsr mailing list > Lsr@ietf.org > https://www.ietf.org/mailman/listinfo/lsr _______________________________________________ Lsr mailing list Lsr@ietf.org https://www.ietf.org/mailman/listinfo/lsr
