Re: [spring] SRv6 Network Programming Endpoint Behavior Registry

[Ron Bonica <[e-mail]>]

Pablo,

Could you make that clear in Section 9.2. I read it the other way.

                                                    Ron



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From: spring <[e-mail]> On Behalf Of Pablo Camarillo (pcamaril)
Sent: Thursday, December 19, 2019 12:54 PM
To: Joel M. Halpern <[e-mail]>; [e-mail]
Subject: Re: [spring] SRv6 Network Programming Endpoint Behavior Registry


Joel,



Thank you for your question. Your original understanding is correct.



The table “SRv6 Endpoint Behaviors” contains behaviors. Behaviors are not present in the SRv6 SIDs. They are only used in the control plane.



As you requested, here is the relevant piece of text:



Section 2 (Terminology):

   SRv6 SID function: The function part of the SID is an opaque

   identification of a local behavior bound to the SID.  It is formally

   defined in Section 3.1<https://urldefense.com/v3/__https:/tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-07*section-3.1__;Iw!!NEt6yMaO-gk!Tn0ixA8x2Ed5xdLusNrH5HC99oVHX3PApoLzm8_-CjRjg_FpGKlElWvuxlqgN9rY$> of this document.



   SRv6 segment endpoint behavior: A packet processing behavior executed

   at an SRv6 segment endpoint.


Section 3.1 (SID Format):

   This document defines an SRv6 SID as consisting of LOC:FUNCT:ARG,

   where a locator (LOC) is encoded in the L most significant bits of

   the SID, followed by F bits of function (FUNCT) and A bits of

   arguments (ARG).

...

   The FUNCT is an opaque identification of a local behavior bound to

   the SID.



   The term "function" refers to the bit-string in the SRv6 SID.  The

   term "behavior" identifies the behavior bound to the SID.


Section 9.2 (IANA)

    Table 3: SRv6 Endpoint Behaviors Registry



Thank you,

Pablo.



-----Original Message-----

From: spring <[e-mail]<mailto:[e-mail]>> on behalf of "Joel M. Halpern" <[e-mail]<mailto:[e-mail]>>

Date: Thursday, 19 December 2019 at 16:35

To: "[e-mail]<mailto:[e-mail]>" <[e-mail]<mailto:[e-mail]>>

Subject: [spring] SRv6 Network Programming Endpoint Behavior Registry



    In talking with folks, and looking at the draft, I realized that there

    were two different interpretations of the Endpoint Behavior Registry.

    I can not tell which is intended.



    I had assumed, possibly incorrectly, that the list of code points was a

    list of code points to use in routing and control protocols (so all the

    control mechanisms sould have inter-changeable semantics for SRv6 SIDs.

    I thus assumed that one would see in routing an advertisement that in

    some form said "SID prefix X is serviced by node Y and provides

    functionality of Endpoint Behavior Z, with the remaining bits as defined

    in the registry."



    Other folks have read this text as defining the bits that must appear in

    the explicit SID in the SID list, between the loactor portion and the

    arguments.  This would provide some small savings in the routing and

    control infrastructure (but not a lot since there still need to be

    advertisements about what Endpoint Behaviors each node actually

    supports.)  This would seem to constrain implementations to use exactly

    these code point.  I am reminded of diffserv, where we looked at doing

    that and concluded that operator needs were such that it did not make

    sense to mandate the on-the-wire code point.



    Can the authors please clarify which meaning they intend?  Possibly by

    pointing me at the wording in the document that makes it clear?



    Thank you,

    Joel



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