Re: [mpls] Concerns about ISD

Hi Greg,

Your statement is floating in the area.
I am confused. You asked me some questions on specific use cases.  I replied with my point with reason. But here you jumped to some other things, like a philosophy thing. What’s your thoughts on my reply on each of you question? If you disagree, what’s your proposal and how does it work better?
If you want to discuss PW, I would like to know firstly the use cases. Signaling or data traffic? How ISD is more flexible?

Best,
Tianran

From: Greg Mirsky [mailto:gregimirsky@gmail.com]
Sent: Wednesday, April 13, 2022 10:44 PM
To: Tianran Zhou <zhoutianran@huawei.com>
Cc: John E Drake <jdrake@juniper.net>; Tony Li <tony.li@tony.li>; mpls@ietf.org
Subject: Re: [mpls] Concerns about ISD

Hi Tianran,
thank you for sharing your thoughts. Of course, there's no way to slice the bread and whether to use only PSD comes with its limitations like burning a value for the first nibble after the BoS. And it needs to interwork with PW CW and ACH/G-ACH. I see an ISD-based solution as more flexible and easier to apply to MPLS PWs.

Regards,
Greg

On Wed, Apr 13, 2022 at 12:16 AM Tianran Zhou <zhoutianran@huawei.com<mailto:zhoutianran@huawei.com>> wrote:
Hi Greg,

Please see my thoughts in line.

Cheers,
Tianran

From: Greg Mirsky [mailto:gregimirsky@gmail.com<mailto:gregimirsky@gmail.com>]
Sent: Wednesday, April 13, 2022 10:10 AM
To: Tianran Zhou <zhoutianran@huawei.com<mailto:zhoutianran@huawei.com>>
Cc: John E Drake <jdrake@juniper.net<mailto:jdrake@juniper.net>>; Tony Li <tony.li@tony.li<mailto:tony.li@tony.li>>; mpls@ietf.org<mailto:mpls@ietf.org>
Subject: Re: [mpls] Concerns about ISD

Hi Tianran,
I have got several questions based on the discussion we had of the use cases and hope you could share your opinion:

  *   Do you see a benefit of supporting EL using NMA? If EL is supported by NMA, should it be in ISD or PSD?
ZTR> I do not see the “benefit”.  I think EL is a mature thing, already implemented everywhere. There is no need to duplicate.

  *   If NMA supports GISS, where do you see it - ISD or PSD?
ZTR> I will use PSD to support slicing, as this one: https://datatracker.ietf.org/doc/html/draft-li-mpls-enhanced-vpn-vtn-id-02.

  *   If NMA to support IOAM in MPLS be only Preallocated Trace Option and Direct Export types, would you consider carrying the IOAM Header in ISD?
ZTR> I am not going to use ISD for IOAM. At first look, IOAM data format is already specified.  I do not see how to encode into ISD, with inconsecutive space(S bit in between).
Regards,
Greg

On Tue, Apr 12, 2022 at 6:17 PM Tianran Zhou <zhoutianran=40huawei.com@dmarc.ietf.org<mailto:40huawei.com@dmarc.ietf.org>> wrote:
Hi,

Comments in line.

Tianran

Juniper Business Use Only
From: mpls <mpls-bounces@ietf.org<mailto:mpls-bounces@ietf.org>> On Behalf Of Tianran Zhou
Sent: Tuesday, April 12, 2022 2:36 AM
To: Tony Li <tony.li@tony.li<mailto:tony.li@tony.li>>
Cc: mpls@ietf.org<mailto:mpls@ietf.org>
Subject: Re: [mpls] Concerns about ISD

[External Email. Be cautious of content]

Hi Tony,

>>Pushing data to PSD and beyond the RLSD will cause systems to be excluded from the path or take a significant performance hit.

If I know the RLSD of each node, there are many ways to prevent some nodes from pushing data to PSD.

[JD]  Given that you *only* want to use PSD, what is the above sentence proposing?

ZTR> If you followed the past few emails, Tony misled people that PSD will hinder the interoperability. I just show you how PSD will not. According to your description below on the ISD process, it’s the same as PSD somehow. I did not see the ISD advantage.

I would like to know how ISD could survive if the ISD exceed the RLSD?

[JD]  The correct term is Network Actions  Sub-stack (NAS).  To answer your question, a transit node will miss the NAS regardless of whether it contains in-stack data.  This is the point that Tony has been making for the past few email iterations

ZTR> Creating new terms does not help the community. I do not care the fancy term you created. Could you please point me out how many times Tony has clarified the ISD process? And where they are? I may have missed.
In my brain, Tony did not address any of my concerns on ISD, but only kept ignoring the fact I presented. It’s not a good way for technique discussion.

Best,
Tianran

From: Tony Li [mailto:tony1athome@gmail.com] On Behalf Of Tony Li
Sent: Tuesday, April 12, 2022 2:03 PM
To: Tianran Zhou <zhoutianran@huawei.com<mailto:zhoutianran@huawei.com>>
Cc: mpls@ietf.org<mailto:mpls@ietf.org>
Subject: Re: [mpls] Concerns about ISD

Hi Tianran,

ZTR2> PSD can work with RLSD, I cannot see how it will hinder the interoperability.

Pushing data to PSD and beyond the RLSD will cause systems to be excluded from the path or take a significant performance hit.

Tony

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