Re: [spring] 6man w.g. last call for <draft-ietf-6man-spring-srv6-oam> - END.OTP

["Zafar Ali (zali)" <[e-mail]>]

Hi Greg,

The END.OTP SID is NOT defined or to be used for in-situ OAM.

Thanks

Regards … Zafar

From: ipv6 <[e-mail]> on behalf of Greg Mirsky <[e-mail]>
Date: Thursday, December 19, 2019 at 10:21 AM
To: Robert Raszuk <[e-mail]>
Cc: SPRING WG <[e-mail]>, 6man WG <[e-mail]>
Subject: Re: [spring] 6man w.g. last call for <draft-ietf-6man-spring-srv6-oam> - END.OTP

Hi Robert,
thank you for your quick response. Could you please help me understand how this proposed mechanism complements what is defined in the combination of iOAM data<https://tools.ietf.org/html/draft-ietf-ippm-ioam-data-08> and iOAM in IPv6<https://tools.ietf.org/html/draft-ietf-ippm-ioam-ipv6-options-00> drafts? As I understand it, the data draft already includes the mechanism to trigger the timestamp collection on a node by setting the appropriate flags in the IOAM-Trace-Type field. And the IOAM-Trace-Type field is part of iOAM in IPv6 encapsulation. If that is the case, I don't see the gap that needs to be closed but the duplication of functionality by the proposed END..OTP function.

Regards,
Greg

On Thu, Dec 19, 2019 at 7:06 AM Robert Raszuk <[e-mail]<mailto:robert@raszuk..net>> wrote:
Hi Greg,

> I believe that iOAM already has defined a method to collect timestamps
> and the method to trigger timestamping described in the draft we're
> discussing is duplicating that. Would you agree?

Nope not at all.

The timestamping is needed in the SR paths in the outer header. iOAM says:


   Scope: This document defines the data fields and associated data

   types for in-situ OAM.  The in-situ OAM data field can be transported

   by a variety of transport protocols, including NSH, Segment Routing,

   Geneve, IPv6, or IPv4.  Specification details for these different

   transport protocols are outside the scope of this document.



I think current SR OAM draft fills that gap.



Thx

R.





On Thu, Dec 19, 2019 at 3:49 PM Greg Mirsky <[e-mail]<mailto:[e-mail]>> wrote:
Hi Robert,
could you please clarify your statement "there is huge value in defining packet timestamping in all oam documents IETF produces these days"? Is that applicable to Active OAM methods or to other OAM methodologies, including, Passive and Hybrid? If the timestamping operation is entirely local to a networking node is applied to a data flow, in other words, the timestamp value is not stored in the forwarded downstream data packet, which performance metric your expect to produce? Or is the expectation to use the Alternate Marking methodology, as described in RFC 8321, in combination with the local timestamping? If the product of the timestamping operation is stored in the data packet, then how is that different from what is already described in the iOAM draft you've referenced? I believe that iOAM already has defined a method to collect timestamps and the method to trigger timestamping described in the draft we're discussing is duplicating that. Would you agree?

Regards,
Greg

On Thu, Dec 19, 2019 at 1:56 AM Robert Raszuk <[e-mail]<mailto:[e-mail]>> wrote:
Hi Joel,

>  However, there is no defined behavior that I know of that can make use
> of this timestamp.

Not sure how to read that statement. Are you expecting IETF draft to tell vendor that computing delta of N values is needed ? Or is IETF draft needed to tell packet analyzers to evaluate the quality of the path based on packets timestamps ? Yes routers may never be involved in such processing, but other network monitoring components do.

Sure current networking in this regard is in stone ages, but there are real efforts and working code which goes beyond that already in place. Example: https://tools.ietf.org/html/draft-ietf-ippm-ioam-data-08

So there is huge value in defining packet timestamping in all oam documents IETF produces these days and it would be rather disservice to remove such important option.

Thx,
r.


On Thu, Dec 19, 2019 at 1:45 AM Joel M. Halpern <[e-mail]<mailto:[e-mail]>> wrote:
If I am reading the draft correctly, the difference between END.OP and
END.OTP is that an internal process is to attach in some internal
location a timestamp to the packet.  In the abstract, I understand why
such cna be useful.

However, there is no defined behavior that I know of that can make use
of this timestamp.  Until such a behavior is defined, what is the value
in defining the END.OTP behavior?  (Taken in the extreme, until there is
such a definition, any implementation which treated END.OTP as END.OP
would seem to be indistinguishable from proper operation in terms of
behavior on the wire.)

Yours,
Joel

On 12/18/2019 7:01 PM, Zafar Ali (zali) wrote:
> Hi Joel,
>
> Thanks for your review.
>
> The processing details were embedded in the Section 4.
>
> We brought them up in the Section 3 and also added additional normative
> language in Section 4.
>
> We have been maintaining the latest version of the draft in the Github...
>
> However, we also posted the latest diffs, which addresses your comments
> as follows:
>
>   * In the new revision, we have added normative text at the beginning
>     of 3.1.1 where O-bit is defined.
>   * Sections 3.3 and 3.4 adds normative texts for OAM SIDs.
>   * 4.1.2 and 4.2.2 further adds additional normative text for Ping and
>     traceroute use-cases, respectively.
>
> Latest version is kept in the Github and also uploaded as
> https://www.ietf.org/staging/draft-ietf-6man-spring-srv6-oam-03.txt.
>
> Thanks
>
> Regards … Zafar
>
> *From: *"Joel M. Halpern" <[e-mail]<mailto:[e-mail]>>
> *Date: *Thursday, December 5, 2019 at 10:01 PM
> *To: *"Zafar Ali (zali)" <[e-mail]<mailto:[e-mail]>>, 6man WG <[e-mail]<mailto:[e-mail]>>,
> SPRING WG <[e-mail]<mailto:[e-mail]>>
> *Subject: *Re: 6man w.g. last call for <draft-ietf-6man-spring-srv6-oam>
>
> Sorry, minor typo.  SRH, not NSH, in the 4th paragraph.
>
> Joel
>
> On 12/5/2019 9:42 PM, Joel M. Halpern wrote:
>
>     The normative behavior for the bits in various places says that the
>
>     packet is punted to the control process.  In and of itself, that is
>     fine.
>
>     However, in order for that to be useful, the control process has to
>     know
>
>     what to do with the packet when it gets there.  In the classic case of
>
>     router redirect, this is coupled with definition of various content to
>
>     be processed by the router control logic.
>
>     In the case of this document, there is no normative definition of what
>
>     the control process is to do with the packet.  And particularly
>     since in
>
>     many of the cases described the packet that is punted still has an SRH,
>
>     normal packet processing would simply reach the same "punt" step.  With
>
>     nowhere to punt it.
>
>     You asssume in the examples that some forms of parsing that bypass the
>
>     NSH will take place.  But processing does not take place by instinct or
>
>     magic.  It takes place because we write RFCs that describe what has to
>
>     happen.  Without some definition of the required parsing, and I believe
>
>     (although I am guessing due to the lack of description) we also need
>
>     some normative description of what the control process is required
>     to do.
>
>     Note that in most OAM, we define the behavior that is required, and
>     then
>
>     indicate where it is permitted to use the control plane to achieve it.
>
>     This results in a clear specification, and implementation flexibility.
>
>     Yours,
>
>     Joel
>
>     On 12/5/2019 9:34 PM, Zafar Ali (zali) wrote:
>
>         Hi Joel,
>
>         I did not understand your comment.
>
>         Can you please point to specific text in the draft for which the
>         draft
>
>         needs to define normative behavior for the "node punt processor
>         look
>
>         past the SRH and make determinations based on the content."?
>
>         Thanks
>
>         Regards … Zafar
>
>         *From: *ipv6 <[e-mail]<mailto:[e-mail]>
>         <mailto:[e-mail]<mailto:[e-mail]>>> on behalf of "Joel M. Halpern"
>
>         <[e-mail]<mailto:jmh@joelhalpern...com> <mailto:[e-mail]<mailto:[e-mail]>>>
>
>         *Date: *Wednesday, December 4, 2019 at 4:37 PM
>
>         *To: *Ole Troan <[e-mail]<mailto:[e-mail]>
>         <mailto:[e-mail]<mailto:[e-mail]>>>, 6man WG <[e-mail]<mailto:[e-mail]>
>         <mailto:[e-mail]<mailto:[e-mail]>>>,
>
>         SPRING WG <[e-mail]<mailto:[e-mail]> <mailto:[e-mail]<mailto:[e-mail]>>>
>
>         *Subject: *Re: 6man w.g. last call for
>         <draft-ietf-6man-spring-srv6-oam>
>
>         I re-read this draft, and I am afraid it is currently
>         under-specified.
>
>         In order for the various examples to work, there is assumed
>         behavior by
>
>         the processor to which packets are punted.  I could not find
>         where this
>
>         normative behavior is described explicitly.  It appears that the
>
>         behavior requires that the node "punt processor" look past the
>         SRH and
>
>         make determinations based on the content.  This needs to be
>         described
>
>         explicitly.  And it needs some discussion of why it is legitimate to
>
>         look past the SRH when the SRH does not show SL=0.
>
>         Yours,
>
>         Joel
>
>         On 12/4/2019 3:53 PM, Ole Troan wrote:
>
>              Hello,
>
>                   As agreed in the working group session in Singapore, this
>
>              message starts a new two week 6MAN Working Group Last Call on
>
>         advancing:
>
>                   Title    : Operations, Administration, and Maintenance
>         (OAM) in
>
>              Segment Routing Networks with IPv6 Data plane (SRv6)
>
>                   Author   : Z. Ali, C. Filsfils, S. Matsushima, D.
>         Voyer, M. Chen
>
>                   Filename : draft-ietf-6man-spring-srv6-oam-02
>
>                   Pages    : 23
>
>                   Date     : 2019-11-20
>
>         https://datatracker.ietf.org/doc/draft-ietf-6man-spring-srv6-oam/
>
>              as a Proposed Standard.
>
>              Substantive comments and statements of support for
>         publishing this
>
>              document should be directed to the mailing list.
>
>              Editorial suggestions can be sent to the author. This last
>         call will
>
>              end on the 18th of December 2019.
>
>              To improve document quality and ensure that bugs are caught
>         as early
>
>              as possible, we would require at least
>
>              two reviewers to do a complete review of the
>         document.  Please let
>
>              the chairs know if you are willing to be a reviewer.
>
>              The last call will be forwarded to the spring working
>         group, with
>
>              discussion directed to the ipv6 list.
>
>              Thanks,
>
>              Bob & Ole, 6man co-chairs
>
>
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