The discussion prompted me to read this draft. I have two different
questions about it:
1) In what way is it related to L4S? Yes, L4S uses ECN. But ECN is not
restricted to L4S.
2) Even if we assume this only reports packets with ECN bits enabled
(not 00), generating an IPFIX report for every data packet across many
flows (in some environments, all flows) seems to be tremendous
overhead. Since as I understnad it this is for management monitoring of
operability, not for congestion response, that seems a massive
overhead. Am I misreading the draft?
Yours,
Joel
On 1/11/2026 9:54 PM, [email protected] wrote:
Hi Greg,
Thank you for the good question.
Yes, ECN is an end-to-end protocol, TCP sender intiates the signalling
and TCP receiver responds. And I think IPFIX works in IP layer, so the
target data extraction is at network nodes. For the information
elements proposed in this drfat, the IPFIX extraction position may be
different based on monitoring purposes. We plan to add the following
text to section 5, does it work for you?
/The IPFIX IEs defined in this draft may have their information
extraction positions adjusted based on different ECN monitoring
purposes in the network. Among them, the basic ECN field elements are
used to reflect the ECN codepoints carried in the IPv4 header, the
IPv6 Traffic Class octet, or the MPLS EXP field. These fields can be
flexibly extracted at any node along the path that has IPFIX export
capability. For tunnel ECN negotiation status IEs, the IPFIX data can
only be provided by the specific tunnel endpoints that participate in
the negotiation. For cumulative statistics IEs, the statistical data
may be processed with a higher priority at traffic aggregation or
egress nodes./
For the mpls-ecn draft you shared, it appers to define a new ECN
opcode encapsulated in MNA packets for MPLS data plane. I think it's
actually relevant to the ipfix-ecn draft, if MPLS WG adopts it, we
would like to add the ECN export from MPLS MNA packets to our draft.
Best regards,
Xueyan
Original
*From: *GregMirsky <[email protected]>
*To: *宋雪雁00038118;Joel Halpern <[email protected]>;
*Cc: *[email protected] <[email protected]>;[email protected]
<[email protected]>;mpls <[email protected]>;
*Date: *2026年01月11日 06:00
*Subject: **Re: [OPSAWG]Fw: New Version Notification for
draft-song-opsawg-ipfix-ecn-00.txt*
Hi Xueyan,
thank you for sharing the updated draft. A relatively new draft
draft-halmir-mpls-ecn
<https://datatracker.ietf.org/doc/draft-halmir-mpls-ecn/> on
supporting ECN in the MPLS using MNA might be of interest to you and
others involved in the matter. And I have a question. As I understand
the ECN, it is a host that is expected to act on the information
collected in the ECN field along the path of a packet. If that is
correct, who's the intended target of the IPFIX notification about the
ECN? Is the intention to act on ECN information obtained on a segment,
e.g., a tunnel, rather than based on the e2e ECN information? I read
Section 5, but was left with these questions.
Regards,
Greg
On Fri, Jan 9, 2026 at 1:53 AM <[email protected]> wrote:
Hello OPSAWG and TSVWG,
We submited a new draft and posted it in the IETF datatracker
https://datatracker.ietf.org/doc/draft-song-opsawg-ipfix-ecn/
The following IPFIX information elements are introduced for L4S
ECN monitoring:
- ECN field capture in protocol layer, including ECN field in
IPv4/IPv6 ECN field, MPLS EXP and tunnel ECN negotiation status
- ECN codepoint statistics, including incremenatl and total count
for non-ECT, ECT(0), ECT(1) and CE packets
- L4S performance indicator, providing short-term and long-term
view of congestion experienced by L4S traffic
Your review, comments and questions are welcome.
Best regards,
Xueyan
Original
*From: *[email protected] <[email protected]>
*To: *宋雪雁00038118;刘尧00165286;
*Date: *2025年12月26日 16:33
*Subject: **New Version Notification for
draft-song-opsawg-ipfix-ecn-00.txt*
A new version of Internet-Draft draft-song-opsawg-ipfix-ecn-00.txt has been
successfully submitted by Xueyan Song and posted to the
IETF repository.
Name: draft-song-opsawg-ipfix-ecn
Revision: 00
Title: Export of L4S ECN in IP Flow Information Export (IPFIX)
Date: 2025-12-26
Group: Individual Submission
Pages: 14
URL:
https://www.ietf.org/archive/id/draft-song-opsawg-ipfix-ecn-00.txt
Status: https://datatracker.ietf.org/doc/draft-song-opsawg-ipfix-ecn/
HTML:
https://www.ietf.org/archive/id/draft-song-opsawg-ipfix-ecn-00.html
HTMLized:
https://datatracker.ietf.org/doc/html/draft-song-opsawg-ipfix-ecn
Abstract:
This document defines a set of IP Flow Information Export (IPFIX)
Information Elements for monitoring the Low Latency, Low Loss, and
Scalable throughput (L4S) service. Specially, these elements enable
network operators to monitor the Explicit Congestion Notification
(ECN) information of L4S deployment and performance of traffic.
The IETF Secretariat
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