Hi, All:
I read carefully again the WGLC draft, and OBJECT strongly for its forwarding. The reasons are the followings: Section I: Decent IETF Behaviors 1) The scenario, initial solution and intense discussions are described, initiated, organized by the authors of https://datatracker.ietf.org/doc/html/draft-wang-lsr-prefix-unreachable-annoucement-00 (From October 2019), there is no any mentions in this document for these experts’ efforts. This is not the decent behavior within IETF. 2) The idea of https://datatracker.ietf.org/doc/html/draft-ietf-lsr-igp-ureach-prefix-announce-04#section-4 is first describe in https://datatracker.ietf.org/doc/html/draft-wang-lsr-prefix-unreachable-annoucement-06#section-7 (March, 2021), ONE YEAR Earlier than the initial draft of the WGLC document.( https://datatracker.ietf.org/doc/html/draft-ppsenak-lsr-igp-ureach-prefix-announce-00) (March, 2022). This is another non-decent behavior within IETF. Section II: Technical Analysis 1) The WGLC provide two methods to label the unreachable prefixes, one depends on LSInifinity setting of the advertised prefix, the other depends on the newly defined flag. They are redundancy and confusion. The meaning of LSinifinity is already defined in the existing documents, and there is no necessary to rephrase them. The solution needs only depend on one method. 2) For the usage of LSInifinity, although RFC 2328 and RFC 5305 defines its possible usage, if they are used in such way(I have not heard any operator deploy such mechanics), their deployment should be gradually disappearing, not enhance instead. There are three reasons for such considerations: a) The maximum metric value is often treated as the last resort of reachability, not the unreachability. It will lead more confusions for the setting of such metric in the network. b) It states clearly in the RFC 2328 section 14.1, that “Premature aging can also be used when, for example, one of the router's previously advertised external routes is no longer reachable. In this circumstance, the router can flush its AS- external-LSA from the routing domain via premature aging. This procedure is preferable to the alternative, which is to originate a new LSA for the destination specifying a metric of LSInfinity." c) During the SPF calculation, the final cost is the summary of every segment cost. It is possible that the final cost exceed also the LSinfinity, but the prefix is reachable. 3) For the Signaling Method, it defines the additional flags based one newly defined sub-TLV for OSPF, and existing sub-TLV for IS-IS. Far complex than the usage of “Prefix Originator” directly. The document just want to make some differences, not the efficiency. 4) The WGLC document doesn’t solve the area/domain partition scenaro, which may appear in the network, and is already covered by https://datatracker.ietf.org/doc/draft-wang-lsr-prefix-unreachable-annoucement/ (let’s call it Founder Document). It states, “UPA does not make the problem of an area partition any worse. ”-----Actually, it does worse----If one ABR can’t reach the egress router(PE1), but another ABR can reach, there should be no switchover of the egress router(PE2), which may be reachable, or may be unreachable.-----There should be some coordinate mechanism among the ABRs, as that described in the above Founder Document. 5) There is no any consideration for the balance of reachable information and unreachable information announcements. It will be disaster in some critical condition. Best Regards Aijun Wang China Telecom 发件人: forwardingalgori...@ietf.org [mailto:forwardingalgori...@ietf.org] 代表 Aijun Wang 发送时间: 2025年4月22日 0:12 收件人: Yingzhen Qu <yingzhen.i...@gmail.com> 抄送: lsr <lsr@ietf.org>; lsr-chairs <lsr-cha...@ietf.org> 主题: [Lsr] Re: WG Last Call for draft-ietf-lsr-igp-ureach-prefix-announce (4/17/2025 - 5/2/2025) I object its forwarding, from the beginning of its WG adoption. Aijun Wang China Telecom On Apr 18, 2025, at 02:13, Yingzhen Qu <yingzhen.i...@gmail.com <mailto:yingzhen.i...@gmail.com> > wrote: Hi, This email begins a 2 week WG Last Call for the following draft: IGP Unreachable Prefix Announcement https://datatracker.ietf.org/doc/draft-ietf-lsr-igp-ureach-prefix-announce/ Please review the document and indicate your support or objections by May 2nd, 2025. Authors and contributors, Please indicate to the list your knowledge of any IPR related to this work. Thanks, Yingzhen _______________________________________________ Lsr mailing list -- lsr@ietf.org <mailto:lsr@ietf.org> To unsubscribe send an email to lsr-le...@ietf.org <mailto:lsr-le...@ietf.org>
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