Hello Ran and WG, I support the adoption of this proposal, as the quantitative criteria significantly improve the reliability of SR Policy validation. I have a few suggestions that I believe will add clarity and value to the draft.
*Point 1: Enhancing Section 3 (Validity of a Candidate Path)* The problem is well-defined in Section 2, but adding brief explanations and example scenarios of how the new attributes—"valid SL count" and "valid SL weight"—address the problem would be highly beneficial. *Valid SL count:* For example, with the topology shown in Section 2, if the operator configures a minimum valid SL count of 2, the Candidate Path (CP) will be rendered invalid as soon as a single Segment List (SL) goes down. This prevents the CP from remaining active when its capacity is halved and insufficient for the full traffic load. *Valid SL weight:* This attribute can be used to ensure a minimum required capacity. Consider two Segment Lists: SL1 (capacity 100MB) and SL2 (capacity 200MB). The operator configures weights proportional to capacity: SL1 has weight 1 and SL2 has weight 2. To ensure the CP remains active only when the higher capacity path (SL2) is available, the operator can set the minimum required valid SL weight to 2. If SL2 goes down, the remaining weight is 1, the criterion is not met, and the CP is correctly declared invalid. *Point 2: Clarifying Capacity in Section 2 (Motivation)* The existing text in the Motivation section can be enhanced to clearly establish the capacity limits of the Segment Lists, which is the core reason for the problem. *Proposed revised text for the first paragraph of the Motivation section ( something like ..):* The SR Policy POL1 has two candidate paths: CP1 and CP2, and CP1 is the active candidate path. The two segment lists (SL1 and SL2) of CP1 are installed as the forwarding instantiation of SR Policy POL1. These segment lists are assumed to have a maximum capacity of 100MB each that they can carry. The CP1 carries a total of 200MB of traffic. Within POL1, flow-based hashing is used over its SLs with a 50% ratio, so each SL carries 100MB of traffic. At this time, if one of the segment lists is determined to be invalid by the rule defined in RFC 9256, the remaining Segment List cannot carry the full 200MB of traffic due to its capacity limit. However, the CP1 is still considered active according to RFC 9256. *Point 3: Clarifying "valid SL weight"* While "valid SL count" clearly refers to the number of valid SLs, the term "valid SL weight" could be ambiguous. A reader might interpret it as the required weight of an individual Segment List, rather than the intended sum of the weights of all valid Segment Lists. I suggest rephrasing this attribute in the text to explicitly clarify that it represents the minimum cumulative weight of all valid Segment Lists on the Candidate Path. Thanks, Imtiyaz - Individual On Thu, 27 Nov 2025 at 07:08, <[email protected]> wrote: > Hi, > > I think the topic of when the candidate path is valid and the validation > criteria is an important topic, which can make SR Policy to fulfill the SLA > requirements better. > > It seems that there's not a whole picture in this draft yet to show how > the enhanced CP validation method works in the network, maybe some > descriptions of the control/management plane function can be added. > > > Regards, > > Yao > > > Original > *To: *[email protected] <[email protected]>; > *Cc: *[email protected] <[email protected]>; > *Date: *2025年11月25日 17:05 > *Subject: **[spring] Request for Discussion: Validity of SR Policy > Candidate Path* > _______________________________________________ > spring mailing list -- [email protected] > To unsubscribe send an email to [email protected] > > Hi WG， > > We would like to initiate a discussion on the > https://datatracker.ietf.org/doc/draft-chen-spring-sr-policy-cp-validity/ > . > > This draft builds upon RFC 9256 and it adds further considerations to the > existing validation mechanisms in RFC 9256, with a focus on improving the > current approach to CP validity checks.It defines new quantitative criteria > (e.g., > minimum valid SL count and weight) to refine the CP validity determination > specified in RFC 9256, addressing limitations inherent in the simple "at > least one active SID-List" criterion. > > This work is critical for improving the reliability and operational > accuracy of SR Policy deployments. > > We request feedback on the mailing list to help us advance this draft. > Thank you! > > > BR, > > Ran > > > > _______________________________________________ > spring mailing list -- [email protected] > To unsubscribe send an email to [email protected] >
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