Hi Joel,
Thank you for taking time to read the draft, and providing new aspects we need
to consider, we will make updates to the draft to reflect your comments.
Please also see my reply inline.
Best regards,
Xueyan (on behalf-of co-authors)
Original
From: JoelHalpern <[email protected]>
To: 宋雪雁00038118;
Cc: [email protected] <[email protected]>;[email protected]
<[email protected]>;[email protected] <[email protected]>;
Date: 2026年01月12日 23:56
Subject: [tsvwg] Re: [OPSAWG]Fw: New Version Notification for
draft-song-opsawg-ipfix-ecn-00.txt
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.
>>Xueyan: The main consideration for L4S service is that L4S introduces a new
>>ECN codepoint ECT(1) for traffic identification, it helps the diferenciation
>>between classical and L4S traffic and uses CE codepoint for potential
>>congestion mark. The monitoring of ECN can provide Operators with valuable
>>insights, including the ratio of L4S traffic in the network, statistics of
>>network congestion and granular visibility for the performance of L4S
>>services.
But the ECN monitoring in this draft is not limited to L4S, for example, we
also provide the monitoring IEs for ECN(0) and non-ECT, with a flexible design
to satisfy user's monitoring requirements.
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?
>>Xueyan: Yes, we agree that doing this per packets would create too much
>>overhead. In real deployment, IPFIX performs probalistic sampling for data
>>collection based on user requirements instead of extracting data per packet.
>>The specifi data export is determined by IPFIX configurations and device
>>capabilities, but the general rule is to avoid creating heavy overhead to
>>network nodes.
Best regards
Xueyan
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
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 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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