Re: [OPSAWG] Benjamin Kaduk's No Objection on draft-ietf-opsawg-vpn-common-10: (with COMMENT)

[[e-mail]]

Hi Ben, 

Thank you for the follow-up. 

Please see inline. 

Cheers,
Med

> -----Message d'origine-----
> De : Benjamin Kaduk <[e-mail]>
> Envoyé : lundi 27 septembre 2021 23:39
> À : BOUCADAIR Mohamed INNOV/NET <[e-mail]>
> Cc : The IESG <[e-mail]>; [e-mail];
> [e-mail]; [e-mail]; [e-mail]
> Objet : Re: Benjamin Kaduk's No Objection on draft-ietf-opsawg-vpn-common-
> 10: (with COMMENT)
> 
> Hi Med,
> 
> On Wed, Sep 22, 2021 at 09:40:17AM +0000, [e-mail]
> wrote:
> > Hi Ben,
> >
> > Thank you for the review. The changes to address your review can be
> > tracked at:
> > https://github.com/IETF-OPSAWG-WG/lxnm/commit/108707e8b2aea6590b0a9695
> > 756c7546887c9614
> 
> Thanks.  Also inline...
> 
> 
> >
> > Please see inline.
> >
> > Cheers,
> > Med
> >
> > > -----Message d'origine-----
> > > De : Benjamin Kaduk via Datatracker [mailto:[e-mail]] Envoyé
> > > : mercredi 22 septembre 2021 06:19 À : The IESG <[e-mail]> Cc :
> > > [e-mail]; [e-mail];
> > > [e-mail]; [e-mail]; [e-mail] Objet :
> > > Benjamin Kaduk's No Objection on draft-ietf-opsawg-vpn-common-
> > > 10: (with COMMENT)
> > >
> > > Benjamin Kaduk has entered the following ballot position for
> > > draft-ietf-opsawg-vpn-common-10: No Objection
> > >
> > > When responding, please keep the subject line intact and reply to
> > > all email addresses included in the To and CC lines. (Feel free to
> > > cut this introductory paragraph, however.)
> > >
> > >
> > > Please refer to https://www.ietf.org/blog/handling-iesg-ballot-
> > > positions/
> > > for more information about how to handle DISCUSS and COMMENT
> positions.
> > >
> > >
> > > The document, along with other ballot positions, can be found here:
> > > https://datatracker.ietf.org/doc/draft-ietf-opsawg-vpn-common/
> > >
> > >
> > >
> > > --------------------------------------------------------------------
> > > --
> > > COMMENT:
> > > --------------------------------------------------------------------
> > > --
> > >
> > > I have a bold proposal for consideration: since we are defining a
> > > new common set of groupings for VPN and, in some cases, proposing to
> > > rename existing terminology already, can we consider moving away
> > > from the term "VPN" itself?  The word "private" is ambiguous as to
> > > what level of privacy is being provided (e.g., network routing vs
> > > cryptographic) and who the conveyed content is to be private from.
> > > A term like "virtual network" removes that ambiguity, and lets us
> > > use the explicit attributes to convey whether encryption is in use
> when appropriate.
> > >
> > > There is no particular triggering point (at least, not yet) at which
> > > it becomes clearly correct to make a breaking change like this, so
> > > we may end up just having to pick a time somewhat arbitrarily, if we
> > > are to make such a change at all.  Perhaps now is that time; perhaps
> not.
> >
> > [[Med]] I hear some of your observations but VPN is a well-established
> name for a widely deployed technology. I don't think it is a good idea to
> touch this. Please note that there is already generic model for VNs
> (https://datatracker.ietf.org/doc/draft-ietf-teas-actn-vn-yang/) that is
> distinct from what we are doing here.
> 
> Well, I don't think that just because VPN is well-established we should
> ignore the ambiguity in what it describes.  So, I still want to touch it
> at some point, but do not insist on doing so right now.  I am sure that we
> can find some non-VPN term other than VN if there is desire to
> distinguish...but we can defer that conversation, of course.

[Med] Sure, we can always find better names, but I think it is better to have this discussion when revising documents such as RFC4026. Thank you. 

> 
> > >
> > > Section 3
> > >
> > >           grouping vpn-profile-cfg
> > >             +-- valid-provider-identifiers
> > >                +-- external-connectivity-identifier* [id]
> > >                |       {external-connectivity}?
> > >                |  +-- id?   string
> > >
> > > Presumably I am just misreading RFC 8340, but I thought that the
> > > list key was implicitly mandatory, so it would appear as just "id"
> > > (as opposed to "id?").  (Many instances.)
> >
> > [[Med]] Good question. Actually we trusted what is in Section 3.2 of
> 8340. That's the output we get from pyang. Note that ? is not displayed
> when the grouping is used in another model (L2NM/L3NM). Will double check
> this with Martin.
> 
> Thanks.
> 
> > >
> > >    'vpn-route-targets':
> > >       *  A YANG grouping that defines Route Target (RT) import/export
> > >          rules used in a BGP-enabled VPN (e.g., [RFC4364][RFC4664]).
> > >
> > > On very quick skim, it's not clear what motivates the RFC 4664
> > > reference
> > > -- "route target" does not appear, for example, nor does "import" or
> > > "export".
> >
> > [[Med]] This is just to insist that it can be used for both L3 and
> L2VPNs. Unlike L3NM, there are plenty L2VPN technologies; hence the choice
> to point to a generic L2 framework.
> 
> Okay, so the references are just generic "VPN" (or "BGP-enabled VPN")
> references, and I was misreading to ascribe more meaning to them.
> 
> If we wanted to spend a few more words (far from clear), maybe "(suitable
> VPN technologies include but are not limited to [RFC4364][RFC4664])".

[Med] OK. Changed the text to: "This grouping can be used for both L3VPNs [RFC4364] and L2VPNs [RFC4664]."

> 
> > >
> > > Section 4
> > >
> > >      identity pim-proto {
> > >        if-feature "pim";
> > >        base routing-protocol-type;
> > >
> > > This is in the section with the group-management-protocols; is
> > > "routing- protocol-type" really the intended base?
> >
> > [[Med]] Yes. Both PIM and other group management protocols fall under:
> >
> >   /*
> >    * Identities related to multicast
> >    */
> >
> > >
> > >      identity embb {
> > >      [...]
> > >      identity urllc {
> > >      [...]
> > >      identity mmtc {
> > >
> > > Similar to Roman's comment, a reference seems useful for these.
> > > If we intend to implicitly rely on RFCs 8299 and/or 8466 for
> > > terminology, we should say so in the terminology section.
> >
> > [[Med]] Added this note under the terminology section:
> >
> >    The document inherits many terms from [RFC8299] and [RFC8466]
> >    (e.g., Enhanced Mobile Broadband (eMBB), Ultra-Reliable and Low
> >    Latency Communications (URLLC), Massive Machine Type Communications
> >    (mMTC)).
> 
> Thanks!
> 
> > >
> > >        leaf vpn-id {
> > >          type vpn-common:vpn-id;
> > >          description
> > >            "A VPN identifier that uniquely identifies a VPN.
> > >             This identifier has a local meaning, e.g., within
> > >             a service provider network.";
> > >
> > > Thank you for indicating the scope of validity of the identifier!
> > > (Elsewhere as well.)
> > >
> > >      grouping service-status {
> > >        [...]
> > >            leaf last-change {
> > >              type yang:date-and-time;
> > >              description
> > >                "Indicates the actual date and time of the service
> status
> > >                 change.";
> > >
> > > What's the motiviation behind leaving this as "config true"?  When
> > > would it be useful to set it manually?
> >
> > [[Med]] This can be set, for example, when a new administrative status
> is set.
> 
> But would it be set to a time other than the time when the new
> administrative status was set, i.e., a value that can be automatically
> determined?

[Med] Yes, think about service calendaring scenarios. 

> 
> > >
> > >        list vpn-target {
> > >          [...]
> > >          leaf id {
> > >            type int8;
> > >            description
> > >              "Identifies each VPN Target.";
> > >
> > > I wasn't able to find the motivation for limiting to int8 in RFC
> > > 4364, though I mostly assume I'm just looking in the wrong place.
> >
> > [[Med]] I confirm that there is no such concept in 4364. The intuitive
> design would be to use leaf-list, but the reason for having this is a list
> with an id is recorded in this note:
> >
> >          Note that this is modelled as a list to ease the reuse of this
> >          grouping in modules where a pointer is needed (e.g., associate
> >          an operator with RTs).
> >
> > We don't see the need to go beyond uint8. As illustrated, for example,
> in L3NM a typical usage of this would be simply:
> 
> Okay.  I am not sure if "pointer" or "index" is better for conveying the
> desired meaning ("pointer" might suggest "leafref" to some readers).

[Med] Changed to "where an RT identifier". 

> 
> > ==
> >                          "vpn-targets": {
> >                            "vpn-target": [
> >                              {
> >                                "id": "1",
> >                                "route-targets": [
> >                                  "0:65550:1"
> >                                ],
> >                                "route-target-type": "both"
> >                              }
> >                            ]
> >                          }
> > ==
> >
> > > (But why *signed* int8?)
> >
> > [[Med]] This should be unsigned. Fixed.
> >
> > >
> > > Section 5
> > >
> > > While there may be no direct security considerations from what is
> > > effectively just defining some new compound types for reuse, I think
> > > we may want to consider some privacy considerations.  For example,
> > > we have the "customer-name" field in the vpn-description, and it is
> > > sometimes the case that customers want to remain confidential.
> > > Thus, any instantiations of the grouping would incur a potential
> > > need for confidentiality and minimizing the scope of distribution.
> > >
> >
> > [[Med]] We do already discuss this for example in the L3NM. No problem
> to add a note here as well. I added this NEW text:
> >
> >    Modules that use the groupings that are defined in this document
> >    should identify the corresponding security considerations.  For
> >    example, reusing some of these groupings will expose privacy-related
> >    information (e.g., customer-name).  Disclosing such information may
> >    be considered as a violation of the customer-provider trust
> >    relationship.
> 
> Thanks, that looks good.
> 
> >
> > > NITS
> > >
> > > Section 4
> > >
> > >      feature bearer-reference {
> > >        description
> > >          "Indicates support for the bearer reference access
> constraint.
> > >           That is, the reuse of a network connection that was already
> > >           ordered to the service provider apart from the IP VPN
> > > site.";
> > >
> > > I echo Roman's comment that this feature would benefit from a
> > > reference or further discussion; the current description leaves me
> > > unclear on what is meant and with no recourse for learning more.
> > > (RFCs 4026 and 4176 are presented as generic references for
> > > VPN-related terms, but do not cover the concept of "bearer
> > > reference".)
> >
> > [[Med]] The description is basically echoing RFC8299:
> >
> > ==
> >    o  The "bearer-reference" parameter is used in cases where the
> >       customer has already ordered a network connection to the SP apart
> >       from the IP VPN site and wants to reuse this connection.
> > ==
> >
> > We can update the description to first introduce the concept of bearer:
> >
> >       "A bearer refers to properties of the CE-PE attachment that
> >        are below Layer 3.
> 
> Thanks; combined with the note in the intro about 8299 terminology that
> should be enough for people to figure it out.
> 
> And thanks for the other updates as well,
> 
> Ben


_________________________________________________________________________________________________________________________

Ce message et ses pieces jointes peuvent contenir des informations confidentielles ou privilegiees et ne doivent donc
pas etre diffuses, 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.

This message and its attachments may contain confidential or 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.
As emails may be altered, Orange is not liable for messages that have been modified, changed or falsified.
Thank you.