Re: [ippm] FW: New Version Notification for draft-li-ippm-otwamp-on-lag-02.txt

Hi Henrik,

This draft is not targeting for your case. China mobile raised the LAG PM requirement in their network.

But as I mentioned in the introduction, it could be potentially used for SR policy with L3 multi hops. This is out of scope. But I would happy to share my point. :-)

Best,
Tianran

________________________________

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发件人： Henrik Nydell<hnydell@accedian.com<mailto:hnydell@accedian.com>>
收件人： Tianran Zhou<zhoutianran@huawei.com<mailto:zhoutianran@huawei.com>>
抄送： wangaj3<wangaj3@chinatelecom.cn<mailto:wangaj3@chinatelecom.cn>>;IETF IPPM WG<ippm@ietf.org<mailto:ippm@ietf.org>>
主题： Re: [ippm] FW: New Version Notification for draft-li-ippm-otwamp-on-lag-02.txt
时间： 2022-01-27 20:20:53

In my mind TWAMP, being a layer-3 method, is more commonly used on longer e-2-e layer3 connections, for example sender from a central core site out to a reflector on a radio base station. The path between may have several layer3 hops and many layer-2. If there is LAG somewhere there in the middle of the path, how will this draft help?

On Thu, Jan 27, 2022 at 12:48 PM Tianran Zhou <zhoutianran@huawei.com<mailto:zhoutianran@huawei.com>> wrote:
Hi Henrik,

May I understand what’s the limits?
The twamp or lag? Or other?
Actually both are supported in existing devices. As far as I know quite normal.

Best,
Tianran

________________________________

Sent from WeLink
发件人： Henrik Nydell<hnydell@accedian.com<mailto:hnydell@accedian.com>>
收件人： Tianran Zhou<zhoutianran@huawei.com<mailto:zhoutianran@huawei.com>>
抄送： wangaj3<wangaj3@chinatelecom.cn<mailto:wangaj3@chinatelecom.cn>>;IETF IPPM WG<ippm@ietf.org<mailto:ippm@ietf.org>>
主题： Re: [ippm] FW: New Version Notification for draft-li-ippm-otwamp-on-lag-02.txt
时间： 2022-01-27 18:15:39

OK, but this requires that the sender runs on the device that performs the LAG. This would be quite a serious limitation of the feature I believe

On Thu, Jan 27, 2022 at 10:48 AM Tianran Zhou <zhoutianran@huawei.com<mailto:zhoutianran@huawei.com>> wrote:
Hi Henrik,

Both sender and reflector keep the mapping between member link and the micro session. Either by configuration or negotiation or auto-learning.
So, in your switch case, if the sender receives the packet from C, not A, the sender know it’s wrong. The test packet should be dropped and not counted.

Best,
Tianran
From: Henrik Nydell [mailto:hnydell@accedian.com<mailto:hnydell@accedian.com>]
Sent: Thursday, January 27, 2022 5:29 PM
To: Tianran Zhou <zhoutianran@huawei.com<mailto:zhoutianran@huawei.com>>
Cc: wangaj3@chinatelecom.cn<mailto:wangaj3@chinatelecom.cn>; IETF IPPM WG <ippm@ietf.org<mailto:ippm@ietf.org>>
Subject: Re: [ippm] FW: New Version Notification for draft-li-ippm-otwamp-on-lag-02.txt

Thanks for the clarification, but this "member link validation mechanism" depends fully on configuration between the session sender and the session reflector right? So even if they have agreed that a certain session ID belongs to lag link A, there is no way to be sure that this is the case, the intermediate switches may place these packets randomly over links A-C and the TWAMP/OWAMP sender/reflectors will have no knowledge of this. So I dont know if this addition adds much usefulnes over the already existing capabilities of TWAMP, where you can use the 5-tuple of port-pair, IP-pair and TOS to differentiate session from each other.

On Thu, Jan 27, 2022 at 2:37 AM Tianran Zhou <zhoutianran@huawei.com<mailto:zhoutianran@huawei.com>> wrote:
Hi Henrik,

Thanks very much for your review.
Your perspective is absolutely correct.
This draft is not able to “guarantee” a specific LAG path. For example, there is a switch between the two end points, or in the case the reflector is not capable.
I.e., as you said, there is no "one method fits all" to guarantee the path.

However, this draft seek another way round, the member link validation mechanism.
There is an assumption in the introduction “This document intends to address the scenario where a LAG directly connects two nodes (A and B).”
With the member link validation, sender/reflector will drop measurement data, when the test packet is not from the expected member link.
In this way, the measurement could always be correct.

This is somewhat similar to Paris Traceroute (https://paris-traceroute.net/about/) IMHO.

Cheers,
Tianran

From: Henrik Nydell [mailto:hnydell@accedian.com<mailto:hnydell@accedian.com>]
Sent: Wednesday, January 26, 2022 6:17 PM
To: Tianran Zhou <zhoutianran@huawei.com<mailto:zhoutianran@huawei.com>>
Cc: wangaj3@chinatelecom.cn<mailto:wangaj3@chinatelecom.cn>; IETF IPPM WG <ippm@ietf.org<mailto:ippm@ietf.org>>
Subject: Re: [ippm] FW: New Version Notification for draft-li-ippm-otwamp-on-lag-02.txt

I had a brief review but failed to find details on how the TWAMP sessions would be "guaranteed" to travel on a certain LAG segment. As far as I know the LAG implementation may be different between vendors and as such I know of no "one method fits all" to actually accomplish the measurement.

So this draft does not actually provide any solution to the problem of being able to measure LAG segments separately and deterministically.

On Wed, Jan 26, 2022 at 11:03 AM Tianran Zhou <zhoutianran=40huawei.com@dmarc.ietf.org<mailto:40huawei.com@dmarc.ietf.org>> wrote:
Hi Anjun,

Thanks very much for your interest and comments.
Both are good questions.
Please see in line.

Cheers,
Tianran

-----Original Message-----
From: wangaj3@chinatelecom.cn<mailto:wangaj3@chinatelecom.cn> [mailto:wangaj3@chinatelecom.cn<mailto:wangaj3@chinatelecom.cn>]
Sent: Wednesday, January 26, 2022 5:21 PM
To: Tianran Zhou <zhoutianran@huawei.com<mailto:zhoutianran@huawei.com>>; 'IETF IPPM WG' <ippm@ietf.org<mailto:ippm@ietf.org>>
Subject: RE: [ippm] FW: New Version Notification for draft-li-ippm-otwamp-on-lag-02.txt

Hi, Tianran:

Have a brief review of this draft. I think its aim is straightforward and will be useful to utilize the member link within the LAG.
Some comments are below:
1) It seems there is no Sender/Reflector behavior description for the Mirco OWAMP session and the packet format?

ZTR> OWAMP is simple and there is no reflector. The sender cannot get the ack from the receiver. So we are not going to extend the OWAMP test packet.
The behavior is described in section 3.2:
" The micro OWAMP Sender MUST send the micro OWAMP-Test packets over the member link with which the session is associated. When receives a Test packet, the micro OWAMP receiver MUST use the member link from which the Test packet is received to correlate the micro OWAMP session. If there is no such a session, the Test packet MUST be discarded. "

2) For the newly defined Session-Sender Packet/Session-Reflector Packet, how to assure the backward compatibility? What I have seen is that you add two additional fields within the existing Packet?

ZTR> I am not aware of the compatibility problem. If a node supports micro session, it can understand the new packet extension. If a node does not support micro session, it just ignores the new fields. Because the new fields is in the reserved zone.
Moreover, the validation mechanism can figure out if the reflector can support the micro session.

Best Regards

Aijun Wang
China Telecom

-----Original Message-----
From: ippm <ippm-bounces@ietf.org<mailto:ippm-bounces@ietf.org>> On Behalf Of Tianran Zhou
Sent: Monday, January 24, 2022 2:23 PM
To: IETF IPPM WG (ippm@ietf.org<mailto:ippm@ietf.org>) <ippm@ietf.org<mailto:ippm@ietf.org>>
Subject: [ippm] FW: New Version Notification for draft-li-ippm-otwamp-on-lag-02.txt

Hi WG,

We think this is an useful work on adapting OWAMP/TWAMP in LAG performance measurement.
We updated this draft based on the comments from the meeting discussion and mailing list.
Thanks for all the suggestions.
More reviews and comments are welcome.

Cheers,
Tianran

-----Original Message-----
From: internet-drafts@ietf.org<mailto:internet-drafts@ietf.org> [mailto:internet-drafts@ietf.org<mailto:internet-drafts@ietf.org>]
Sent: Monday, January 24, 2022 2:17 PM
To: Greg Mirsky <gregimirsky@gmail.com<mailto:gregimirsky@gmail.com>>; Guo Jun <guo.jun2@zte.com.cn<mailto:guo.jun2@zte.com.cn>>; Jun Guo <guo.jun2@zte.com.cn<mailto:guo.jun2@zte.com.cn>>; Rakesh Gandhi <rgandhi@cisco.com<mailto:rgandhi@cisco.com>>; Tianran Zhou <zhoutianran@huawei.com<mailto:zhoutianran@huawei.com>>; Zhenqiang Li <li_zhenqiang@hotmail.com<mailto:li_zhenqiang@hotmail.com>>
Subject: New Version Notification for draft-li-ippm-otwamp-on-lag-02.txt

A new version of I-D, draft-li-ippm-otwamp-on-lag-02.txt
has been successfully submitted by Tianran Zhou and posted to the IETF repository.

Name:           draft-li-ippm-otwamp-on-lag
Revision:       02
Title:          One-way/Two-way Active Measurement Protocol Extensions for
Performance Measurement on LAG
Document date:  2022-01-24
Group:          Individual Submission
Pages:          13
URL:
https://www.ietf.org/archive/id/draft-li-ippm-otwamp-on-lag-02.txt
Status:
https://datatracker.ietf.org/doc/draft-li-ippm-otwamp-on-lag/
Htmlized:
https://datatracker.ietf.org/doc/html/draft-li-ippm-otwamp-on-lag
Diff:
https://www.ietf.org/rfcdiff?url2=draft-li-ippm-otwamp-on-lag-02

Abstract:
   This document defines extensions to One-way Active Measurement
   Protocol (OWAMP), and Two-way Active Measurement Protocol (TWAMP) to
   implement performance measurement on every member link of a Link
   Aggregation Group (LAG).  Knowing the measured metrics of each member
   link of a LAG enables operators to enforce the performance based
   traffic steering policy across the member links.

The IETF Secretariat

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