Re: [pim] Yangdoctors last call review of draft-ietf-pim-igmp-mld-yang-07

[Xufeng Liu <[e-mail]>]

Hi Jan,

Thanks for reviewing.
For #1, as discussed, there is no other better solution at the moment. What
would you suggest?
Thanks.
- Xufeng

On Fri, Oct 19, 2018 at 4:25 AM Jan Lindblad <[e-mail]> wrote:

> Feng,
>
> Hi Jan,
>
> We updated  draft-ietf-pim-igmp-mld-yang according to the comments #2 ~
> #7, while Xufeng and you had discussed about comment #1.
> Please review the draft, thanks a lot.
> https://www.ietf.org/id/draft-ietf-pim-igmp-mld-yang-08.txt
>
>
> Good. I looked through the points #2-#7 and find that the work group have
> understood and fixed those issues. #1 still remains to be resolved. I can
> do a full re-review of the module once that one has been resolved as well.
> Are there any outstanding questions on how to fix #1?
>
> Best Regards,
> /jan
> --
> *Jan Lindblad*, [e-mail], [phone]
> Solutions Architect, Business Development, Tail-f
> Tail-f is now a part of Cisco
>
>
> Feng
>
> -----Original Message-----
> From: Jan Lindblad [mailto:[e-mail] <[e-mail]>]
> Sent: Monday, August 13, 2018 10:35 PM
> To: [e-mail]
> Cc: [e-mail]; [e-mail]; [e-mail]
> Subject: Yangdoctors last call review of draft-ietf-pim-igmp-mld-yang-07
>
> Reviewer: Jan Lindblad
> Review result: On the Right Track
>
> This is my YANG-doctor review of draft-ietf-pim-igmp-mld-yang-07. In the
> spring, I did an early review of the -02 version.
>
> Most of the comments from the earlier review are still valid. In some ways
> the document has progressed since -02, in many it has not, and in a few it
> has deteriorated. In my judgement, the document is not ready for last call.
> Many fundamentally important questions are still unresolved. Here are my
> review comments in rough falling order of importance.
>
> #1 Improper augment of /rt:routing/rt:control-plane-protocols
>
> Quoted from section 3.1:
>    This model augments the core routing data model "ietf-routing"
>    specified in [RFC8349].  The IGMP model augments "/rt:routing/
>    rt:control-plane-protocols" as opposed to augmenting "/rt:routing/
>    rt:control-plane-protocols/rt:control-plane-protocol", as the latter
>    would allow multiple protocol instances, while the IGMP protocol is
>    designed to be enabled or disabled as a single protocol instance on
>    a network instance or a logical network element.
>
> The description above, and the actual augment statements in the YANG
> module violate the principles described in RFC 8349, the ietf-routing.yang
> module it augments. In RFC 8349, section 5.3.  Control-Plane Protocol, the
> proper way of augmenting the routing module is described. The fact that
> this is a singleton protocol instance doesn't change this. Section 5.3
> describes singleton cases as well.
>
> Guofeng: Xufeng has discussed with Jan about the comment, and it is closed.
>
> #2 Incorrect vendor refinement model
>
> Quoted from section 2.2:
>    For the same reason, wide constant ranges (for example, timer
>    maximum and minimum) will be used in the model.  It is expected that
>    vendors will augment the model with any specific restrictions that
>    might be required. Vendors may also extend the features list with
>    proprietary extensions.
>
> This is not acceptable. The principle suggested does not foster
> interoperability and useful standards. It is also not possible to do what
> the paragraph suggests in YANG. This was pointed out in the -02 review, and
> a suggestion was given there on how to address the problem.
>
> Guofeng: We removed the paragraph above, and put the values discussed by
> Mcast Design Team.
>
>
> #3 Top level structures not optional
>
> Quoted from section 2.3:
>    The current document contains IGMP and MLD as separate schema
>    branches in the structure. The reason for this is to make it easier
>    for implementations which may optionally choose to support specific
>    address families. And the names of objects may be different between
>    the IPv4 (IGMP) and IPv6 (MLD) address families.
>
> This problem was also pointed out in the -02 review. The author suggests
> that implementing igmp and/or mld is optional. This is not reflected in the
> YANG module, however. As currently modeled, both are currently mandatory to
> implement. If-feature is used liberally in the module, and could be used
> here as well.
>
> #4 Unclear meaning of optional leaves
>
> Quoted from section 3.1:
>    Where fields are not genuinely essential to protocol operation, they
>    are marked as optional. Some fields will be essential but have a
>    default specified, so that they need not be configured explicitly.
>
> In fact, in the current version of the module, every leaf is optional
> (except keys, which cannot be optional). It is good to see the addition of
> defaults in many cases, but many unclear cases remain. E.g. leaf
> /igmp/global/enable is of type boolean. I understand what true and false
> implies for this leaf. But what does it mean if it is not set at all?
> Either add a default or describe the meaning in the description. Similarly,
> if the leaf version is not set on an igmp or mld interface, or on the
> interface-global level, what does that mean?
> Add default. require-router-alert? explicit-tracking? exclude-lite? Many
> of these are used in NP-containers inheriting all the from the root, which
> makes the use of mandatory highly discouraged in the current form. If the
> RFC 8349 augmentation principles are followed, the concern around mandatory
> falls, and some leafs with no sensible default could be marked mandatory
> instead.
>
> #5 All optional state
>
> All state data is optional, which means a conforming server could very
> well decide not to implement it. E.g. discontinuity-time is optional.
> Should a manager count on this being available? A situation where every
> leaf is optional is as nice and flexible for server implementors as it is
> frustrating and complicated for manager implementors to consume. A YANG
> model is an API contract and should consider the needs of both sides. The
> way this has been designed reveals that no representation for the consumer
> side of this model has been involved in the design. I would suggest
> thinking through what is the most essential state data for a manager, and
> make some leafs mandatory.
>
> #6 Abundant copy-paste
>
> There is abundant repetition in the YANG module. leaf version is defined 2
> times for igmp with identical definitions, and two more for mld with
> identical definitions. leaf enable is defined once for the interface
> global-level, and with identical definition on the interface local level.
> leaf last-member-query-interval, query-interval and half a dozen other
> leaves are defined twice with identical definitions.
>
> #7 Leaf interface in the rpc clear*groups on line 1124, 1094 has type
> string.
> Should be a leafref? Describe what values are valid. #8 Leaf group-policy,
> source-policy on line 486, 527, 624, 689: type string. Should be leafref?
> Describe what values are valid. #9 Leaf group on line 705, 1101, 1131: Is
> any
> ipv4/6 address ok, or only a multicast address? Model accordingly.
>
>
>
>
>
>
> *From:* pim [mailto:[e-mail] <[e-mail]>] *On
> Behalf Of *Jan Lindblad
> *Sent:* Tuesday, September 11, 2018 9:52 PM
> *To:* Xufeng Liu <[e-mail]>
> *Cc:* [e-mail]; ietf <[e-mail]>; [e-mail];
> [e-mail]
> *Subject:* Re: [pim] Yangdoctors last call review of
> draft-ietf-pim-igmp-mld-yang-07
>
> Xufeng,
>
>
> Thanks for the review and valuable comments.
>
> In regard to item #1, there was a discussion thread among the Yang
> Doctors, authors of RFC 8349, and Routing Area Yang Architecture Design
> Team, as attached below.  The discussion occurred during the review of a
> draft with the same issue as this one.
>
>
> I see, didn't know. Good. If this has been discussed to conclusion, then
> you should of course go with that decision.
>
> As mentioned earlier, there are a few other singleton protocols mapped
> into this structure, e.g. static. I think it would make sense to treat this
> the same. Principle of least astonishment.
>
> Best Regards,
> /jan
>
>
>
> ================================
> 原始邮件
> 发件人：XufengLiu <[e-mail]>
> 收件人：Acee Lindem (acee) <[e-mail]>Christian Hopps <[e-mail]>Martin
> Bjorklund <[e-mail]>
> 抄送人：张征00007940;[e-mail] <[e-mail]>
> 日 期 ：2018年02月20日 22:30
> 主 题 ：RE: [yang-doctors] How to restrict to have
> singlecontrol-plane-protocol instance
> Using "" as the name is better, but I am not sure that it is good enough.
> When we use ConfD to translate the model to a command line, if the option
> "tailf:cli-expose-key-name" is not used, we will have:
>
> edit routing control-plane-protocols control-plane-protocol type msdp name
> ''"
>
> If the option "tailf:cli-expose-key-name" is used, we will have:
>
> edit routing control-plane-protocols control-plane-protocol msdp ''"
>
> I am pretty sure that we would get a bug report on this, asking what is
> the purpose to have: name ''", and requesting a suppression on the term,
> but we do not have a good way to achieve.
>
> As a comparison, the option #3 will give:
>
> edit routing control-plane-protocols msdp
>
> This is the only acceptable solution so far. When a model is not usable by
> the end-user, other considerations (such as augmentation convenience) will
> not matter.
>
> Thanks,
> - Xufeng
>
> > -----Original Message-----
> > From: Acee Lindem (acee) [mailto:[e-mail]]
> > Sent: Monday, February 19, 2018 1:35 PM
> > To: Christian Hopps <[e-mail]>; Martin Bjorklund <
> [e-mail]>
> > Cc: Xufeng Liu <[e-mail]>; [e-mail]; yang-
> > [e-mail]
> > Subject: Re: [yang-doctors] How to restrict to have single control-plane-
> > protocol instance
> >
> >
> >
> > On 2/19/18, 5:02 AM, "Christian Hopps" <[e-mail]> wrote:
> >
> >
> >     Martin Bjorklund <[e-mail]> writes:
> >
> >     > Hi,
> >     >
> >     > "Acee Lindem (acee)" <[e-mail]> wrote:
> >     >> All,
> >     >>
> >     >> As seems to be the modus operandi for YANG issues, we have 3
> separate
> > opinions as to how a protocol only supporting a single instance should be
> > realized.
> >     >>
> >     >>   1. Augment the existing control plane protocols list (RFC
> 8022BIS)
> >     >>   and specify in the description text that only a single instance
> is
> >     >>   supported.
> >     >>   2. Augment the existing control plane protocols list (RFC
> 8022BIS)
> >     >>   and use a YANG 1.1 must() restriction as discussed by Martin and
> >     >>   Lada.
> >     >>   3. Augment the container one level up from the list for
> singleton
> >     >>   protocols (suggested by Xufeng).
> >
> >     > But I think there was also a proposal to require the single
> instance
> >     > to have a well-known name - but maybe this proposal is no longer on
> >     > the table.
> >
> >     I actually liked this solution; however, instead of picking an
> arbitrary "well-
> > known" value for name, I would specify the 0 length string instead. I
> think that
> > reinforces the idea that this isn't actually a named instance. :)
> >
> >        augment "/rt:routing/rt:control-plane-protocols/"
> >              + "rt:control-plane-protocol" {
> >           when "derived-from-or-self(rt:type, 'msdp:msdp') and rt:name =
> ''"  {
> >           container msdp {
> >
> > One benefit of this solution is that it solves Xufeng's issue of what
> the client uses
> > as the instance name.
> >
> >
> >     Thanks,
> >     Chris.
> >
> >     >
> >     >
> >     > /martin
> >     >
> >     >
> >     >> and #3. For #3, one determent would be that the control plane
> protocols
> > are in a location other than where they were originally envisioned and I
> don't
> > relish pulling RFC8022BIS off the RFC queue to document.
> >     >>
> >     >> Thanks,
> >     >> Acee
> >     >>
> >     >> On 2/15/18, 8:39 AM, "Reshad Rahman (rrahman)" <[e-mail]
> >
> > wrote:
> >     >>
> >     >>     Hi Xufeng,
> >     >>
> >     >>     I think the intent of 8022bis was to have all protocols under
> > /rt:routing/rt:control-plane-protocols/rt:control-plane-protocol. I
> agree that
> > forcing a name for a single-instance is cumbersome, but I think it is
> too late to
> > change tree hierachy organization at this point.
> >     >>
> >     >>     I will defer to other YDs and 8022bis authors on this.
> >     >>
> >     >>     Regards,
> >     >>     Reshad.
> >     >>
> >     >>     On 2018-02-08, 9:48 AM, "Xufeng Liu" <[e-mail]>
> wrote:
> >     >>
> >     >>         Hi All,
> >     >>
> >     >>         I feel that such a solution is still not clean enough to
> outweigh the
> > simple augmentation to "/rt:routing/rt:control-plane-protocols/".
> >     >>
> >     >>         Some considerations are:
> >     >>
> >     >>         - Name management: Neither the operator nor the
> implementation
> > wants to deal with the artificial name, whether it is hardcoded,
> user-configured,
> > or system-generated. When we implement such singleton protocol, we don't
> > save a name anywhere.
> >     >>         - The complexity of validation: The "when" statement is an
> > unnecessary expense to the user and to the implementation, especially if
> we
> > need to check all instances.
> >     >>         - Data tree query: If the singleton "MSDP" is mixed with
> other protocol
> > instances, it is less obvious or harder to search for. Depending on the
> > implementation, it would be worse if the entire list needs to be
> iterated.
> >     >>         - Tree hierarchy  organization: I don't see too big a
> problem with "all
> > single-instance protocols under /rt:routing/rt:control-plane-protocols
> and all
> > the multi-instance ones under
> /rt:routing/rt:control-plane-protocols/rt:control-
> > plane-protocol". If necessary, some of the names can be adjusted.
> >     >>
> >     >>         Thanks,
> >     >>         - Xufeng
> >     >>
> >     >>
> >     >>         > -----Original Message-----
> >     >>         > From: Reshad Rahman (rrahman) [mailto:[e-mail]
> ]
> >     >>         > Sent: Thursday, February 8, 2018 9:41 AM
> >     >>         > To: Ladislav Lhotka <[e-mail]>; Martin Bjorklund
> <mbj@tail-
> > f.com>;
> >     >>         > Acee Lindem (acee) <[e-mail]>
> >     >>         > Cc: [e-mail]; [e-mail];
> Xufeng Liu
> >     >>         > <[e-mail]>
> >     >>         > Subject: Re: [yang-doctors] How to restrict to have
> single control-
> > plane-
> >     >>         > protocol instance
> >     >>         >
> >     >>         > Thanks for the suggestions. I agree that hard-coding
> the name is a
> > bad idea,
> >     >>         > glad that a cleaner way of doing this is possible.
> >     >>         > - We can move the must statement up to restrict max of
> 1 control-
> > plane-
> >     >>         > protocol instance of type msdp?
> >     >>         > - Acee/Lada, should a note be added to section 5.3 of
> 8022bis
> > regarding how
> >     >>         > to enforce single instance? How much of a concern is the
> > performance
> >     >>         > impact in this specific case?
> >     >>         >
> >     >>         > Regards,
> >     >>         > Reshad.
> >     >>         >
> >     >>         > On 2018-02-08, 7:02 AM, "Ladislav Lhotka" <
> [e-mail]> wrote:
> >     >>         >
> >     >>         >     On Thu, 2018-02-08 at 12:39 +0100, Martin Bjorklund
> wrote:
> >     >>         >     > "Acee Lindem (acee)" <[e-mail]> wrote:
> >     >>         >     > > Hi Lada,
> >     >>         >     >
> >     >>         >     > >
> >     >>         >     >
> >     >>         >     > > On 2/8/18, 4:42 AM, "yang-doctors on behalf of
> Ladislav
> > Lhotka"
> >     >>         > <yang-docto
> >     >>         >     > [e-mail] on behalf of [e-mail]>
> wrote:
> >     >>         >     >
> >     >>         >     > >
> >     >>         >     >
> >     >>         >     > >     On Thu, 2018-02-08 at 09:20 +0100, Martin
> Bjorklund wrote:
> >     >>         >     >
> >     >>         >     > >     > Hi,
> >     >>         >     >
> >     >>         >     > >     >
> >     >>         >     >
> >     >>         >     > >     > "Reshad Rahman (rrahman)" <
> [e-mail]> wrote:
> >     >>         >     >
> >     >>         >     > >     > > Hi YDs,
> >     >>         >     >
> >     >>         >     > >     > >
> >     >>         >     >
> >     >>         >     > >     > > MSDP YANG authors want to enforce
> single-instance of
> > MSDP
> >     >>         >     >
> >     >>         >     > >     > > control-plane protocol. The when
> “rt:type =
> > ‘msdp’“ allows
> >     >>         > multiple
> >     >>         >     >
> >     >>         >     > >     > > control-pane-protocol instances as long
> as they have
> > different
> >     >>         >     >
> >     >>         >     > >     > > rt:name. The only workaround I thought
> of is to have a
> > when
> >     >>         >     > statement
> >     >>         >     >
> >     >>         >     > >     > > on the name in the top level container.
> This would still
> > multiple
> >     >>         >     >
> >     >>         >     > >     > > control-plane-protocol instance of type
> msdp but
> > restricts the
> >     >>         > name
> >     >>         >     > to
> >     >>         >     >
> >     >>         >     > >     > > a fixed name (msdp-protocol in this
> case) for the top level
> > msdp
> >     >>         >     >
> >     >>         >     > >     > > container to exist. Any suggestions on
> how to do this
> > better?
> >     >>         >     >
> >     >>         >     > >     >
> >     >>         >     >
> >     >>         >     > >     > Hard-coding a name like this is IMO a bad
> idea.
> >     >>         >     >
> >     >>         >     > >     >
> >     >>         >     >
> >     >>         >     > >     > Better would be to simply state in text
> that there MUST
> > only be one
> >     >>         >     >
> >     >>         >     > >     > instance of this type.
> >     >>         >     >
> >     >>         >     > >     >
> >     >>         >     >
> >     >>         >     > >     > But you can also add a must statement
> that enforces this:
> >     >>         >     >
> >     >>         >     > >     >
> >     >>         >     >
> >     >>         >     > >     >    augment
> "/rt:routing/rt:control-plane-protocols/"
> >     >>         >     >
> >     >>         >     > >     >          + "rt:control-plane-protocol" {
> >     >>         >     >
> >     >>         >     > >     >       when 'derived-from-or-self(rt:type,
> "msdp:msdp"'  {
> >     >>         >     >
> >     >>         >     > >     >      container msdp {
> >     >>         >     >
> >     >>         >     > >     >        must
> 'count(/rt:routing/rt:control-plane-protocols/'
> >     >>         >     >
> >     >>         >     > >     >           + '
> rt:control-plane-protocol['
> >     >>         >     >
> >     >>         >     > >     >           + '
> derived-from-or-sel(../rt:type, "msdp:msdp")])
> > <=
> >     >>         >     > 1'";
> >     >>         >     >
> >     >>         >     > >     >
> >     >>         >     >
> >     >>         >     > >     >
> >     >>         >     >
> >     >>         >     > >     > In general, you should be careful with
> the usage of "count",
> > since it
> >     >>         >     >
> >     >>         >     > >     > will loop through *all* instances in the
> list every time.  If
> > the list
> >     >>         >     >
> >     >>         >     > >     > is big, this can have a performance
> impact.
> >     >>         >     >
> >     >>         >     > >
> >     >>         >     >
> >     >>         >     > >     Instead of count(), it is possible to use
> the so-called
> > Muenchian
> >     >>         >     > method:
> >     >>         >     >
> >     >>         >     > >
> >     >>         >     >
> >     >>         >     > >         container msdp {
> >     >>         >     >
> >     >>         >     > >           must
> "not(../preceding-sibling::rt:control-plane-
> > protocol["
> >     >>         >     >
> >     >>         >     > >              + "derived-from-or-self(rt:type,
> 'msdp:msdp')])";
> >     >>         >     >
> >     >>         >     > >           ..
> >     >>         >     >
> >     >>         >     > >         }
> >     >>         >     >
> >     >>         >     > >
> >     >>         >     >
> >     >>         >     > >     It basically states that the
> control-plane-protocol containing
> > the
> >     >>         >     > "msdp"
> >     >>         >     >
> >     >>         >     > >     container must not be preceded with a
> control-plane-
> > protocol entry
> >     >>         > of
> >     >>         >     > the
> >     >>         >     >
> >     >>         >     > >     msdp:msdp type (or derived).
> >     >>         >     >
> >     >>         >     > >
> >     >>         >     >
> >     >>         >     > > This looks like an elegant solution.
> >     >>         >     >
> >     >>         >     >
> >     >>         >     > "elegant" as in "less obvious" ;)  It has the
> same time complexity
> > as
> >     >>         >     > the count() solution.
> >     >>         >
> >     >>         >     It should be faster on the average - it has to scan
> only preceding
> > siblings of
> >     >>         >     the MSDP protocol instance whereas count() always
> has to check
> > *all*
> >     >>         > protocol
> >     >>         >     instances.
> >     >>         >
> >     >>         >     It is true though that in XSLT this technique can
> be made
> > considerably
> >     >>         > more
> >     >>         >     efficient by using indexed keys.
> >     >>         >
> >     >>         >     Lada
> >     >>         >
> >     >>         >     >
> >     >>         >     >
> >     >>         >     > However, since the key for the
> control-plane-protocol  list is
> > "type
> >     >>         >     > name", won't it only work if the previous sibling
> has a  "name"
> > that
> >     >>         >     > is precedes the one being added?
> >     >>         >     >
> >     >>         >     > For each list entry that has this container, the
> expression is
> >     >>         >     > evaluated.  It will scan all preceding entries
> and ensure that there
> >     >>         >     > are none with this type.  So the order of the
> entries doesn't
> > matter;
> >     >>         >     > if there are two with the same type, one of them
> has to be
> > before the
> >     >>         >     > other.
> >     >>         >     >
> >     >>         >     >
> >     >>         >     > /martin
> >     >>         >     >
> >     >>         >     >
> >     >>         >     > >
> >     >>         >     >
> >     >>         >     > > Thanks,
> >     >>         >     >
> >     >>         >     > > Acee
> >     >>         >     >
> >     >>         >     > >
> >     >>         >     >
> >     >>         >     > >
> >     >>         >     >
> >     >>         >     > >     Lada
> >     >>         >     >
> >     >>         >     > >
> >     >>         >     >
> >     >>         >     > >     >
> >     >>         >     >
> >     >>         >     > >     > Also note that I use derived-from-or-self
> instead of equality
> > for the
> >     >>         >     >
> >     >>         >     > >     > identity.
> >     >>         >     >
> >     >>         >     > >     >
> >     >>         >     >
> >     >>         >     > >     >
> >     >>         >     >
> >     >>         >     > >     > /martin
> >     >>         >     >
> >     >>         >     > >     >
> >     >>         >     >
> >     >>         >     > >     >
> >     >>         >     >
> >     >>         >     > >     > >
> >     >>         >     >
> >     >>         >     > >     > > Regards,
> >     >>         >     >
> >     >>         >     > >     > > Reshad.
> >     >>         >     >
> >     >>         >     > >     > >
> >     >>         >     >
> >     >>         >     > >     > >   augment
> "/rt:routing/rt:control-plane-protocols/"
> >     >>         >     >
> >     >>         >     > >     > >         + "rt:control-plane-protocol" {
> >     >>         >     >
> >     >>         >     > >     > >      when "rt:type = ‘msdp’"  {
> >     >>         >     >
> >     >>         >     > >     > >       description
> >     >>         >     >
> >     >>         >     > >     > >         "….”;
> >     >>         >     >
> >     >>         >     > >     > >     }
> >     >>         >     >
> >     >>         >     > >     > >     description "….";
> >     >>         >     >
> >     >>         >     > >     > >
> >     >>         >     >
> >     >>         >     > >     > >     container msdp {
> >     >>         >     >
> >     >>         >     > >     > >       when "../rt:name =
> ‘msdp-protocol’"  {
> >     >>         >     >
> >     >>         >     > >     > >         description
> >     >>         >     >
> >     >>         >     > >     > >           "….";
> >     >>         >     >
> >     >>         >     > >     > >       }
> >     >>         >     >
> >     >>         >     > >     > >       description "MSDP top level
> container.";
> >     >>         >     >
> >     >>         >     > >     > >
> >     >>         >     >
> >     >>         >     > >     > >
> >     >>         >     >
> >     >>         >     > >     > > From: "Reshad Rahman (rrahman)" <
> [e-mail]>
> >     >>         >     >
> >     >>         >     > >     > > Date: Monday, February 5, 2018 at 6:25
> PM
> >     >>         >     >
> >     >>         >     > >     > > To: Xufeng Liu <[e-mail]>,
> >     >>         > "[e-mail]"
> >     >>         >     >
> >     >>         >     > >     > > <[e-mail]>
> >     >>         >     >
> >     >>         >     > >     > > Cc: "[e-mail]" <
> [e-mail]>,
> > "Mahesh
> >     >>         > Sivakumar
> >     >>         >     >
> >     >>         >     > >     > > (masivaku)" <[e-mail]>,
> > "[e-mail]"
> >     >>         >     >
> >     >>         >     > >     > > <[e-mail]>,
> > "[e-mail]"
> >     >>         >     >
> >     >>         >     > >     > > <[e-mail]>,
> > "[e-mail]"
> >     >>         >     >
> >     >>         >     > >     > > <[e-mail]>, "
> [e-mail]"
> >     >>         >     >
> >     >>         >     > >     > > <[e-mail]>,
> "tanmoy.kundu@alcatel-
> >     >>         > lucent.com"
> >     >>         >     >
> >     >>         >     > >     > > <[e-mail]>,
> >     >>         > "[e-mail]"
> >     >>         >     >
> >     >>         >     > >     > > <[e-mail]>, "Acee
> Lindem (acee)"
> >     >>         > <[e-mail]>
> >     >>         >     >
> >     >>         >     > >     > > Subject: Re: Hi all, about the
> modification of MSDP YANG
> >     >>         >     >
> >     >>         >     > >     > >
> >     >>         >     >
> >     >>         >     > >     > > Hi Sandy and Xufeng,
> >     >>         >     >
> >     >>         >     > >     > >
> >     >>         >     >
> >     >>         >     > >     > > I understand that you want only 1 MSDP
> instance but I
> > don’t think
> >     >>         >     > that
> >     >>         >     >
> >     >>         >     > >     > > justifies
> /rt:routing/rt:control-plane-protocols. If we do
> > that we
> >     >>         >     >
> >     >>         >     > >     > > will end up with all single-instance
> protocols under
> >     >>         >     >
> >     >>         >     > >     > > /rt:routing/rt:control-plane-protocols
> and all the multi-
> > instance
> >     >>         >     > ones
> >     >>         >     >
> >     >>         >     > >     > > under
> >     >>         >     >
> >     >>         >     > >     > >
> /rt:routing/rt:control-plane-protocols/rt:control-plane-
> > protocol.
> >     >>         >     >
> >     >>         >     > >     > >
> >     >>         >     >
> >     >>         >     > >     > > I am not sure what’s the best way to
> enforce single-
> > instance, I can
> >     >>         >     >
> >     >>         >     > >     > > check with the other YDs on this topic.
> One way it can be
> > done is
> >     >>         > as
> >     >>         >     >
> >     >>         >     > >     > > follows (I’ve added the when statement
> in bold to
> > existing BFD
> >     >>         >     > model),
> >     >>         >     >
> >     >>         >     > >     > > it enforces that the protocol name is
> ‘bfdv1’. So multiple
> >     >>         > instances
> >     >>         >     >
> >     >>         >     > >     > > with rt:type=bfd-types:bfdv1 could be
> created, but only
> > one of
> >     >>         > these
> >     >>         >     >
> >     >>         >     > >     > > instances can have the bfd container.
> This is probably not
> > the
> >     >>         > best
> >     >>         >     >
> >     >>         >     > >     > > way but the point is that IMO protocols
> have to go under
> >     >>         >     >
> >     >>         >     > >     > >
> /rt:routing/rt:control-plane-protocols/rt:control-plane-
> > protocol.
> >     >>         >     >
> >     >>         >     > >     > >
> >     >>         >     >
> >     >>         >     > >     > > Regards,
> >     >>         >     >
> >     >>         >     > >     > > Reshad.
> >     >>         >     >
> >     >>         >     > >     > >
> >     >>         >     >
> >     >>         >     > >     > >   augment
> "/rt:routing/rt:control-plane-protocols/"
> >     >>         >     >
> >     >>         >     > >     > >         + "rt:control-plane-protocol" {
> >     >>         >     >
> >     >>         >     > >     > >      when "rt:type =
> 'bfd-types:bfdv1'"  {
> >     >>         >     >
> >     >>         >     > >     > >       description
> >     >>         >     >
> >     >>         >     > >     > >         "This augmentation is only
> valid for a control-plane
> >     >>         >     > protocol
> >     >>         >     >
> >     >>         >     > >     > >          instance of BFD (type
> 'bfdv1').";
> >     >>         >     >
> >     >>         >     > >     > >     }
> >     >>         >     >
> >     >>         >     > >     > >     description "BFD augmentation.";
> >     >>         >     >
> >     >>         >     > >     > >
> >     >>         >     >
> >     >>         >     > >     > >     container bfd {
> >     >>         >     >
> >     >>         >     > >     > >       when "../rt:name = 'bfdv1'"  {
> >     >>         >     >
> >     >>         >     > >     > >         description
> >     >>         >     >
> >     >>         >     > >     > >           "This augmentation is only
> valid for a control-plane
> >     >>         >     > protocol
> >     >>         >     >
> >
>
>