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
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