And, in https://www.rfc-editor.org/rfc/rfc2328.html#page-135 (Section
12.4.3. Summary-LSAs), it states clearly:
"If a router advertises a summary-LSA for a destination which
then becomes unreachable, the router must then flush the LSA
from the routing domain by setting its age to MaxAge and
reflooding (see Section 14.1)."----Section 14.1 is about how to
"Premature aging of LSAs"
Then, if you want to invalidate one of your advertised LSA, you should use
MaxAge, not LSInfinity.
The LSInfinity, should be limited it's the original meaning----the last
resort of the route to the prefixes.
Best Regards
Aijun Wang
China Telecom
-----Original Message-----
From: lsr-boun...@ietf.org <lsr-boun...@ietf.org> On Behalf Of Huzhibo
Sent: Thursday, October 13, 2022 2:26 PM
To: Peter Psenak <ppsenak=40cisco....@dmarc.ietf.org>; lsr@ietf.org
Subject: Re: [Lsr] RFC 8362 and LSInfinity
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
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