[ippm] Re: Ask WG for review draft-liu-ippm-srv6-bandwidth-measurement

[[e-mail]]

Dear Yisong,

As a contributor. I have reviewed the document and I think it raises from a network operators point of view a very valid point. Even though with the source routing paradigm the forwarding path throughout the network can be chosen at the source, due to multipathing and ECMP hashing, not all the links are always used equally and therefore the network might be over provisioned and congestion can occur.

I find the idea interesting to determine based on the packet flow which interfaces the packet traversed and, if I understood correctly, export the interface speed from each traversed ingress and egress interface of each transit node.

With interface speed I mean

https://datatracker.ietf.org/doc/html/rfc8343#section-5

         leaf speed {
           type yang:gauge64;
           units "bits/second";
           config false;
           description
               "An estimate of the interface's current bandwidth in bits
                per second.  For interfaces that do not vary in
                bandwidth or for those where no accurate estimation can
                be made, this node should contain the nominal bandwidth.
                For interfaces that have no concept of bandwidth, this
                node is not present.";
           reference
             "RFC 2863<https://datatracker.ietf.org/doc/html/rfc2863>: The Interfaces Group MIB -
                        ifSpeed, ifHighSpeed";
         }

I have a few suggestions. At the end of the introduction https://datatracker.ietf.org/doc/html/draft-liu-ippm-srv6-bandwidth-measurement-00#section-1 you are proposing a solution where the interface bandwidth information is being carried within the packet in IPv6 hop by hop options header as one of the solutions.

Please also consider IOAM direct export, RFC 9326 which exports the metrics on each node along the forwarding path to a data collection. Also applicable in IPv6 hop by hop and destination options header. What is missing in IPFIX https://www.iana.org/assignments/ipfix/ipfix.xhtml are interface speed entities.

In https://datatracker.ietf.org/doc/html/draft-liu-ippm-srv6-bandwidth-measurement-00#section-4.1 you are describing a new Hop-by-Hop Options Header carrying the information of the minimum available bandwidth.

With https://datatracker.ietf.org/doc/html/rfc9197#section-4.4.2.2, IOAM Trace Option, where the information is carried in the packet, already has the capability to export ingress and egress interface id. However lacks the information of interface speed but already supports other interesting properties such as transit delay, queue depth or buffer occupancy which might be interesting as well.

In https://datatracker.ietf.org/doc/html/draft-liu-ippm-srv6-bandwidth-measurement-00#section-3.3 you are describing with gRPC and Netconf a YANG based approach to export the data. I suggest to adjust to push based, standardized, approach with YANG-Push RFC 8639/8641. In either case, IPFIX or YANG, new entities/module needs to be defined. I suggest to address this in the same document.

And last but not least. I am a huge fan of running code. I saw that Justin will participate IETF 122 hackathon https://mailarchive.ietf.org/arch/msg/ippm/6kKd42wbIW0P8IpL7nXWWkjyI7o/ an work on a IOAM DEX IPFIX implementation to measure on-path delay. Adding the interface speed information in IPFIX would address your use case. Could be potentially interesting.

Best wishes
Thomas

From: Yisong Liu <[e-mail]>
Sent: Friday, January 10, 2025 8:17 AM
To: ippm <[e-mail]>
Cc: draft-liu-ippm-srv6-bandwidth-measurement <[e-mail]>
Subject: [ippm] Ask WG for review draft-liu-ippm-srv6-bandwidth-measurement

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Dear WG members,


This draft outlines a comprehensive framework that leverages SRv6 capabilities to facilitate efficient and accurate bandwidth measurement. The proposed approach is designed to enhance network performance monitoring by providing timely and precise bandwidth data, thereby improving the visibility and management of bandwidth resources in SRv6 environments. This contribution is expected to aid in better network optimization and performance analysis.

Please find the draft for review at the following link: https://datatracker.ietf.org/doc/draft-liu-ippm-srv6-bandwidth-measurement/.

We hope you can review this draft and share your feedback. Welcome any questions and comments. Your feedback is invaluable to us.

Thank you for your attention and support.
Best Regards
Yisong on behalf of co-authors