Re: [spring] WGLC - draft-ietf-spring-srv6-network-programming

["Ketan Talaulikar (ketant)" <[e-mail]>]

Hi Joel,



I would like to echo the arguments that Bruno has made (and quote part of it) in his summary and then previously on this thread.



QOUTE

The point was related to the usefulness of the optional feature, which has been challenged.

I was trying to say the required argumentation to declare usefulness or usefulness is asymmetric, from a logical discussion stand point.



a) It only requires one person to find it useful, in order to make the feature useful (for that person).

b) In order to state that this is un-useful,  requires to prove that this is never useful.

UNQOUTE



It’s pure logic!



Please check inline below.



-----Original Message-----
From: spring <[e-mail]> On Behalf Of Joel M. Halpern
Sent: 03 March 2020 21:54
To: [e-mail]; Martin Vigoureux <[e-mail]>; [e-mail]
Subject: Re: [spring] WGLC - draft-ietf-spring-srv6-network-programming



I'm sorry, but "in my gear I want an option to move some work around, so I need a protocol behavior for that" is not usually, in and of itself, enough reason to add an optional feature to a protocol.

[KT] To start with, there are other/more use-cases for PSP as have been discussed on the list over the course of the WGLC and before then. I think you are referring to the use-case that Dan Voyer brought up with legacy hardware - I don't see an issue of being practical and sensitive to real world problems and scenarios. This is what results in actual adoption and deployment success. We have options everywhere - the EH themselves are optional … IIRC HBH options were not so recently made optional out of pure consideration of the actual metal out there in the Internet! 😊



At one point there was an argument that PSP was needed for compliant devices that would not be able to process the packet.  It has been pointed out since that such devices would not comply to 8200 (not because of PSP, but because being able to ignore an exhausted routing header is required in 8200).  Having an optional feature to take care of devices which violate a standard again requires some strong evidence to justify it.

[KT] A device can be conformant with RFC8200 even if were punting the packets for local s/w processing in the presence of an EH (or RH in this case). In that case, it would not be doing line-rate forwarding which is the requirement here. This is again a very practical consideration that is rooted in real world problems and deployments.



So no, from where I sit I have not seen a clear explanation of the value for PSP.

[KT] There have been many use-cases and values expressed for PSP by those that have implemented and deployed it. I can understand if you do not appreciate them. But they are optional and it is unfair to deny it to those who need it.



I also do not understand why the authors have resisted the usual solution to this sort of disagreement, namely moving the feature to a separate document.  Given the structure of the network programming draft, and that it is not exhaustive in either flavors or programming behaviors, there is no violence done to the draft by removing this flavor.

[KT] I think we can go by the track record through the progression of this draft. The contentious topics related to SRH insertion were removed by the authors based on WG feedback and technical arguments – note this was done after it was a WG document. This WGLC has gone beyond the usual timeframe and resulted in unusually large amount of technical discussions. We do see that the document has undergone through multiple changes to improve the text as well as fix certain issues.



So by no stretch of imagination can we say that the authors have been resistant to change when such a change was technically warranted. I do not believe the removal of PSP makes practical and technical sense for those who have implemented and deployed it with real world scenarios in mind.



Thanks,

Ketan



Yours,

Joel



On 3/3/2020 10:49 AM, [e-mail]<mailto:[e-mail]> wrote:

> Fernando

>

>> From: spring [mailto:[e-mail]] On Behalf Of Fernando

>> Gont

>> Sent: Monday, March 2, 2020 9:23 PM

>> To: Martin Vigoureux; [e-mail]<mailto:[e-mail]>

>> Cc: [e-mail]<mailto:[e-mail]>; '[e-mail]';

>> draft-ietf-spring-srv6-network-programming

>> Subject: Re: [spring] WGLC -

>> draft-ietf-spring-srv6-network-programming

>>

>> Martin,

>>

>> As an Area Director, what are your thoughts regarding Bruno's claim

>> that this working group (Spring) doesn't have the necessary skills

>> for evaluating the need of a functionality (PSP) that this wg is

>> including in draft-ietf-spring-srv6-network-programming?

>>

>> Specifically, Bruno has noted (in

>> https://mailarchive.ietf.org/arch/msg/spring/or8086G4iYfee5_Icw4PnhkPLBo/):

>>

>> ---- cut here ----

>> Independently of RFC 8200, the question has been raised with regards

>> to the benefit of PSP.

>> My take is that PSP is an optional data plane optimization. Judging

>> its level of usefulness is very hardware and implementation

>> dependent. It may range anywhere from "not needed" to "required for my platform"

>> (deployed if you are network operator, or been sold if you are a

>> vendor), with possible intermediate points along "n% packet

>> processing gain", or "required when combined with a specific other

>> feature". I don't think that the SPRING WG can really evaluate this

>> point (lack of hardware knowledge, lack of detailed information on the hardwares).

>> ---- cut here ----

>>

>>

>> Doesn't this sound a bit like a group is shipping something that it

>> cannot really understand?

>

>

> There have been replied and statement from the WG. E.g. From Dan (network operator) & Jingrong (vendor).

> https://mailarchive.ietf.org/arch/msg/spring/ErcErN39RIlzkL5SKNVAeEWpn

> AI/

>

> My comment is that a statement such as "(1) reduce the load of final destination.", while true in general, is difficult to evaluate, e.g. in term of packet processing gain, or NPU processing resource gain.

> One can say "not on my hardware", but nobody can say "not in your hardware".

>

> And I think that this is along Joel reply (although I would not want

> to speak for Joel) "Do you have any comments on what appears to be the

> significant increase in complexity on the device performing PSP?  The

> question I am trying to get at is about the tradeoff, which needs one to evaluate both sides."

> https://mailarchive.ietf.org/arch/msg/spring/CMSX7ijacRdG8qHlla61ylJNg

> go/

>

>

> So in the end, what we have is the statement "(1) reduce the load of final destination.".

>

> Thanks,

> --Bruno

>

>> Thanks,

>> Fernando

>>

>>

>>

>>

>> On 2/3/20 15:53, Martin Vigoureux wrote:

>>> WG,

>>>

>>> as I had indicated in a previous message I am the one evaluating

>>> consensus for this WG LC.

>>>

>>> I have carefully read the discussions on the list. I acknowledge

>>> that disagreements were expressed regarding what a particular piece

>>> of text of RFC 8200 says, and on which this document builds to

>>> propose an optional capability. Since RFC 8200 is not a product of

>>> the SPRING WG, I have paid specific attention to the messages ([1],

>>> [2], and [3]) sent by the responsible AD of 6MAN and of RFC8200.

>>>

>>> My overall conclusion is that there is support and rough consensus

>>> to move this document to the next stage.

>>>

>>> Bruno will handle the immediate next steps.

>>>

>>>

>>> Martin

>>>

>>>

>>> [1]

>>> https://mailarchive.ietf.org/arch/msg/spring/67ZG76XRezPXilsP3x339rG

>>> pcso/

>>> [2]

>>> https://mailarchive.ietf.org/arch/msg/spring/plidxjZFBnd4_mEzGsLC76F

>>> ZmQ0/

>>> [3]

>>> https://mailarchive.ietf.org/arch/msg/spring/uBYpxPyyBY6bb86Y2iCh3jS

>>> IKBc/

>>>

>>> Le 2019-12-05 à 18:15, [e-mail]<mailto:[e-mail]> a écrit :

>>>> Hello SPRING,

>>>>

>>>> This email starts a two weeks Working Group Last Call on

>>>> draft-ietf-spring-srv6-network-programming [1].

>>>>

>>>> Please read this document if you haven't read the most recent

>>>> version, and send your comments to the SPRING WG list, no later than December 20.

>>>>

>>>> You may copy the 6MAN WG for IPv6 related comment, but consider not

>>>> duplicating emails on the 6MAN mailing list for the comments which

>>>> are only spring specifics.

>>>>

>>>> If you are raising a point which you expect will be specifically

>>>> debated on the mailing list, consider using a specific email/thread

>>>> for this point.

>>>>

>>>> This may help avoiding that the thread become specific to this

>>>> point and that other points get forgotten (or that the thread get

>>>> converted into parallel independent discussions)

>>>>

>>>> Thank you,

>>>>

>>>> Bruno

>>>>

>>>> [1]

>>>> https://tools.ietf.org/html/draft-ietf-spring-srv6-network-programm

>>>> ing-05

>>>>

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>>

>>

>> --

>> Fernando Gont

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> ______________________________________________________________________

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>

> Ce message et ses pieces jointes peuvent contenir des informations

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> exploites ou copies sans autorisation. Si vous avez recu ce message

> par erreur, veuillez le signaler a l'expediteur et le detruire ainsi que les pieces jointes. Les messages electroniques etant susceptibles d'alteration, Orange decline toute responsabilite si ce message a ete altere, deforme ou falsifie. Merci.

>

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> privileged information that may be protected by law; they should not be distributed, used or copied without authorisation.

> If you have received this email in error, please notify the sender and delete this message and its attachments.

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