Hi Authors, I have reviewed the draft. Basically, It is easy to read, but you might need to clarify some details. Please see below for more details. Thanks, Cheng Abstract 1.[Cheng] Which may refer to the whole sentence instead of the links. suggest OLD: In certain scenarios, it is necessary to advertise unreachable links in OSPF, which should be explicitly excluded from the related SPF calculation. NEW： In certain scenarios, it is necessary to advertise unreachable links in OSPF, so that the links can be explicitly excluded from the related SPF calculation. 2. [Cheng]You may not need to add the reference in the abstract, so suggest to remove the RFCXXXX in the abstract. You can add the reference in the introduction section. S/Stub Router Advertisement (RFC 6987)/Stub Router Advertisement 3. [Cheng]you might rephrase the logic of the second paragraph, for example. move "This document updates RFC 6987 and RFC 8770." to the end of this paragraph. Introduction [Cheng]1. The introduction is quite short. Suggest to add move to explain 1.1. what kind of typical scenarios you mean when saying in 'specific' scenarios. 1.2. please clarify traffic engineering purposes and hop-by-hop routing. I do not understand thess two terms clearly, hope to have more info. 1.3. included in a Flexible Algorithm? why a link can be included in a Flexible Algorithm? You may mean the topology associated with the Flexi algo? 2. [Cheng]s/there is a requirement/it is needed 3. which MUST NOT be considered during [Cheng]In the abstract section, should is used, but here, you change to use MUST NOT. Please clarify this point. [Cheng]s/his/This 4.[Cheng] it may be better to say, this document specifies a method of using xxx. section 2 use cases. 1 There is a link available for Traffic Engineering. [Cheng]Please clarify what is TE. You may mean an explicit forwarding path using Adj-SIDs? may use explicit routing? 2. [Cheng]please clafify best-effort. You may mean, loose path or loose forwarding? 3. [Cheng]I do not understand the logic of " If this link is included in the SPF calculations, best-effort traffic may be routed over the link." [Cheng]is the link not availble or not allowed for BE traffic? are you talking about this link is not reachable in SPF calculation, but it can be used in explicit routing? 4. Flex-Algorithm allows OSPF to compute the paths along the constrained topology. [Cheng]I can see your point, but Flex-Algo allows OSPF, since not that correct. suggest to rephrase the logic. 5. The topology used by Flex- Algorithm 128 is shown in Figure 3. [Cheng]I may be wrong. In my understanding, the relation should be 'associated'? not 'used by'? 6. Flex-Algorithm 128 is used for routing particular flows, such as those for specific traffic. [Cheng]it is not clear here. Flex-algo is used for calculating a constrained tologogy? and what is the meaning of 'such as those for specific traffic.' 7. The "Red" links used by Flex-Algorithm 128 are sub-interfaces with dedicated queues for guaranteed bandwidth. [Cheng]again, 'used by' may not be correct. Suggest to review the verbs in this document. 8. Sub-interfaces in other traffic and default topology are omitted from the example figure for clarity. [Cheng]suggest to clarify 'Sub-interfaces in other traffic'. you may delete 'traffic and' [Cheng]s/default topology/the default topology 9. [Cheng] s/So, it is expected/Therefore, it is expected 10. However, these links are also contained in the default topology computed by the normal SPF calculation, and these links may also be used for best-effort traffic. Therefore, it is a problem that the dedicated links for Flex-Algorithm are still reachable in base SPF calculation. [Cheng]what do you mean normal SPF and base SPF here, any different. I actually can understand. But suggest to double check the sync up the correct wording. 11. This allows Flex-Algorithm 128 to route only specific traffic on the "Red" links. [Cheng] suggest to rephrase 'this allows FA 128 to route' Section 3 1. This document specifies that if the IGP metric of a link is advertised as LSLinkInfinity (0xffff), it MUST NOT be considered during the related SPF computation. [Cheng] S/specifies that if the IGP/specifies a mechanism that when the IGP s/it MUST NOT/the link MUST NOT I do not understand 'the related SPF computation.', suggest to explain 'related' 2. LSLinkInfinity is specified. [Cheng]I do not understand， what is the meaning of 'Specified? ' 3.s/The Router-LSA [RFC2328] and [RFC5340]/The Router-LSA [RFC2328][RFC5340] 4.Prior to this specification, OSPF treated links advertised as LSLinkInfinity as reachable [RFC2328] [Cheng]Suggest to rephrase it. As defined in [RFC2328], links that advertised as LSLinkInfinity are treated as reachable in OSPF protocol. Section 4. 1. Support of the Unreachable Link support capability SHOULD be configurable. [Cheng]It is not clear to me in grammer. Might need to double check or rephrase the wording. skip setcion 5, because we do have a YANG doctor. Section6. 1. Causing routing loop might be treated as a security issue? If yes, then suggest to add text to describe it in this section.