Hi Dhruv, You suggestion works to me. Simple and clear. Nice!
Thank you! Cheng From: Dhruv Dhody <dhruv.i...@gmail.com> Sent: Friday, September 20, 2024 2:14 PM To: Cheng Li <c...@huawei.com> Cc: xiong.q...@zte.com.cn; pce@ietf.org; draft-ietf-pce-sr-path-segm...@ietf.org Subject: Re: [Pce] Re: Path segment supporting multiple segment lists in a candidate path Hi Cheng, Quan, On Fri, Sep 20, 2024 at 2:52 PM Cheng Li <c.l=40huawei....@dmarc.ietf.org<mailto:40huawei....@dmarc.ietf.org>> wrote: Hi Quan, Thank you for proposing the text. Please see my comment below. Thanks, Cheng 4.5. Path Attributes Object The Path Attributes (PATH-ATTRIB) Object is used to carry per-path information and to act as a separator between several ERO/RRO objects as per [I-D.ietf-pce-multipath]. As per [RFC9545], a Path Segment can be used to uniquely identify a segment list or multiple segment lists in a candidate path or an SR policy. __OLD__ When a set of path segments are used to identify multiple segment lists, the Path Segment TLV as described in the Section 4.2.1, MUST be carried in the PATH-ATTRIB Object to indicate the per-SR-path information regarding the Path Segment identifier. __OLD__ [Cheng]This might be rephrased. My suggestion. When multiple ERO/RRO objects are included as per [I-D.ietf-pce-multipath], to support multiple segment lists in an Candidate Path [ref to SR policy draft], the Path Segment TLV as described in the Section 4.2.1, MUST be carried in the PATH-ATTRIB Object to identify each SR path associated with a segment list. Dhruv: This use of MUST here means that if a PATH-ATTRIB Object exists, the Path Segment TLV MUST be encoded in it. But we want to do that only in case when a different PSID is used by each segment list. The P flag in LSP Object is used to indicate that the allocation of all path segments need to be done by the PCE. A Path Segment TLV encoded in the LSP Object apply to all the ERO/RRO, while a Path Segment TLV encoded in a PATH-ATTRIB Object only apply to its ERO. In the cases that all the segment lists are sharing a same PSID, the Path Segment TLV can be carried in the LSP Object or each PATH-ATTRIB Object, respectively. Dhruv: I am unsure why we need to highlight the P flag here. The rest of the text makes sense if we set or unset the P flag. Here is my suggestion - The [I-D.ietf-pce-multipath] defines the PATH-ATTRIB object, which carries per-path information and serves as a separator between multiple ERO/RRO objects, enabling the encoding of multiple segment lists in a Candidate Path, as described in [I-D.ietf-pce-segment-routing-policy-cp]. The Path Segment TLV can be optionally included in the PATH-ATTRIB object to associate a segment list with the PSID. It’s important to note that the Path Segment TLV in the PATH-ATTRIB object applies to the path (the immediately following ERO/RRO), whereas the Path Segment TLV in the LSP object applies to all paths in the PCEP message. If the PSID is encoded in the PATH-ATTRIB object, it MUST be used to identify the SR path. Thanks! Dhruv From: xiong.q...@zte.com.cn<mailto:xiong.q...@zte.com.cn> <xiong.q...@zte.com.cn<mailto:xiong.q...@zte.com.cn>> Sent: Friday, September 20, 2024 10:59 AM To: pce@ietf.org<mailto:pce@ietf.org> Cc: draft-ietf-pce-sr-path-segm...@ietf.org<mailto:draft-ietf-pce-sr-path-segm...@ietf.org> Subject: Path segment supporting multiple segment lists in a candidate path Hi PCE WG, A new version has been submitted as per https://www.ietf.org/archive/id/draft-ietf-pce-sr-path-segment-11.txt. But in case of supporting multiple segment lists in a candidate path, it is required to add Path Segment TLV into Path Attributes Object as different path segment may identify different segment list . And in order to make it backward compatible to current implementation, it needs to allow carrying the TLV in both LSP and PATH-ATTRIB object. So I suggest to add a new section to describe this part of extension as following shown. 4.5. Path Attributes Object The Path Attributes (PATH-ATTRIB) Object is used to carry per-path information and to act as a separator between several ERO/RRO objects as per [I-D.ietf-pce-multipath]. As per [RFC9545], a Path Segment can be used to uniquely identify a segment list or multiple segment lists in a candidate path or an SR policy. When a set of path segments are used to identify multiple segment lists, the Path Segment TLV as described in the Section 4.2.1, MUST be carried in the PATH-ATTRIB Object to indicate the per-SR-path information regarding the Path Segment identifier. The P flag in LSP Object is used to indicate that the allocation of all path segments need to be done by the PCE. When one single path segment is used to identify all segment lists, the Path Segment TLV MAY be carried in the LSP Object or PATH-ATTRIB Object. But the Path Segment TLV MUST be ignored in the LSP Object when it is also included in the PATH-ATTRIB Object. What is your thoughts? Any comments and suggestions are welcome. Thanks! Best Regards, Quan _______________________________________________ Pce mailing list -- pce@ietf.org<mailto:pce@ietf.org> To unsubscribe send an email to pce-le...@ietf.org<mailto:pce-le...@ietf.org>
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