Re: [netmod] [Technical Errata Reported] RFC8349 (6251)

["Acee Lindem (acee)" <[e-mail]>]

Hi Tom, 
I fully understood your original comment. There are other problems with this model. See inline.

On 8/11/20, 4:59 AM, "tom petch" <[e-mail]> wrote:

    Tarek

    Picking up on an earlier point,

    ________________________________________
    From: Tarek Saad <[e-mail]>
    Sent: 10 August 2020 21:23

    Hi Acee,

    The existing RPC is used to query (defined AFIs=IPv4/IPv6) RIB to return the matching active route identified by a "destination address".
    The MPLS module is trying to reuse this RPC so to query the MPLS RIB to return the matching active route identified by a "local label".
    The RPC defined in RFC 8349 readily accepts MPLS AFI in it (/rt:routing/rt:ribs/rt:rib/rt:active-route) - unless we augment and suppress it with a "when check".
    IMO, it is reusable as-is but the text below is limiting the leaf name that identifies an entry in RIB to "destination-address" only - in MPLS RIB the entry leaf name that identifies an entry is "local-label".

It is not reusable as is since the augmentation RPC augmentation must have a when statement restricting it to AF MPLS. Also, local-label is a leaf which is applicable to all address families. It cannot be the AF MPLS destination-prefix. This augmentation is missing. 

Thanks,
Acee


    <tp>
    There should be a 'when' check to enforce the 'MUST' but the rules of YANG do not allow it in this structure.  I raised this on the NETMOD list at the time of WGLC and Martin pointed me to a rule in the ABNF which prohibits such a check.  He also said that the rule was not needed and would be a candidate to remove when YANG is revised.

    Hence I have always thought of this MUST in the documentation as a constraint that must be enforced in the YANG

    Tom Petch
            >            action active-route {
            >              description
            >                "Return the active RIB route that is used for the
            >                 destination address.
            >
            >                 Address-family-specific modules MUST augment input
            >                 parameters with a leaf named 'destination-address'.";

    Regards,
    Tarek

    On 8/10/20, 3:27 PM, "Acee Lindem (acee)" <[e-mail]> wrote:

        [External Email. Be cautious of content]


        All (Speaking as an author of RFC 8349),
        I just looked at this in more detail and I don't think the ietf-mpls.yang model should be augmenting the /rt:routing/rt:ribs/rt:rib/rt:active-route RPC. The intent of the RPC is to return the address-family specific active-route corresponding to the destination-address. This model attempts to overload this RPC with a different action all together - returning a route that has the local-label as an optional attribute. I'd reject the Errata and believe the augmentation should be removed from ietf-mpl.yang. Whether it is replaced with a different one is up to the co-authors of ietf-mpls.yang.
        Thanks,
        Acee

        On 8/10/20, 2:29 PM, "Rob Wilton (rwilton)" <[e-mail]> wrote:

            [Resend to hopefully pass recipient limit filter]

            Hi Tom,

            I would be interested to hear from the original authors.

            My impression is that this is a technically reasonable change, but I don't think that an erratum can create a new revision of a YANG module.

            If this erratum was processed as "Hold for document update" then would that be sufficient to do the right thing in the MPLS YANG module?

            Regards,
            Rob


            > -----Original Message-----
            > From: tom petch <[e-mail]>
            > Sent: 10 August 2020 17:32
            > To: RFC Errata System <[e-mail]>; [e-mail]; Acee
            > Lindem (acee) <[e-mail]>; [e-mail]; [e-mail];
            > Rob Wilton (rwilton) <[e-mail]>; [e-mail];
            > [e-mail]; [e-mail]
            > Cc: [e-mail]; [e-mail]
            > Subject: Re: [netmod] [Technical Errata Reported] RFC8349 (6251)
            >
            > From: netmod <[e-mail]> on behalf of RFC Errata System
            > <[e-mail]>
            > Sent: 07 August 2020 16:45
            >
            > <tp>
            > This is the erratum of whose arrival I speculated on this list on June
            > 16th.
            >
            > There is a degree of urgency about it.  The I-D in question is mpls-base-
            > yang, currently in IETF Last Call, which is a Normative dependency of bfd-
            > yang which is a Normative dependency for a small mountain of I-D which
            > have been waiting a year or so (e.g.  ospf-yang).
            >
            > I suspect that the technically perfect solution would involve a YANG
            > union, choice or some such structure but as I said in my Last Call comment
            > I can live with a label that contains such as 'address' encompassing such
            > as 'label' in the context of forwarding.  I take labels to mean what
            > labels mean rather than what I might find in a work of reference.
            >
            > Tom Petch
            >
            > The following errata report has been submitted for RFC8349,
            > "A YANG Data Model for Routing Management (NMDA Version)".
            >
            > --------------------------------------
            > You may review the report below and at:
            > https://urldefense.com/v3/__https://www.rfc-editor.org/errata/eid6251__;!!NEt6yMaO-gk!URK5WVsqD5g7WpzCU1VuzKJA0AUiawXBFLB_gENlsYMrpiMqDtyFoxw8DnSr2A$
            >
            > --------------------------------------
            > Type: Technical
            > Reported by: Tarek Saad <[e-mail]>
            >
            > Section: 7
            >
            > Original Text
            > -------------
            > The RPC "active-route" is used to retrieve the active route in a RIB.
            > RFC8349 defined two AFIs (v4/v6).
            >
            > draft-ietf-mpls-base-yang is defining a new RIB AFI for MPLS as per
            > section 3 in RFC8349.
            >
            > The RPC has a "MUST" statement that all RIBs must augment input
            > parameters with a leaf named 'destination-address'.
            >
            > For MPLS RIB, it makes sense to augment with leaf named 'local-label'
            > since MPLS routes are identified by MPLS label.
            >
            > We ask to make the following change:
            >
            > OLD:
            >            action active-route {
            >              description
            >                "Return the active RIB route that is used for the
            >                 destination address.
            >
            >                 Address-family-specific modules MUST augment input
            >                 parameters with a leaf named 'destination-address'.";
            >
            >
            > Corrected Text
            > --------------
            > NEW:
            >            action active-route {
            >              description
            >                "Return the active RIB route that is used for the
            >                 destination address.
            >
            >                 Address-family-specific modules MUST augment input
            >                 parameters with a suitable leaf that identifies the
            > route.";
            >
            >
            > Notes
            > -----
            >
            >
            > Instructions:
            > -------------
            > This erratum is currently posted as "Reported". If necessary, please
            > use "Reply All" to discuss whether it should be verified or
            > rejected. When a decision is reached, the verifying party
            > can log in to change the status and edit the report, if necessary.
            >
            > --------------------------------------
            > RFC8349 (draft-ietf-netmod-rfc8022bis-11)
            > --------------------------------------
            > Title               : A YANG Data Model for Routing Management (NMDA
            > Version)
            > Publication Date    : March 2018
            > Author(s)           : L. Lhotka, A. Lindem, Y. Qu
            > Category            : PROPOSED STANDARD
            > Source              : Network Modeling
            > Area                : Operations and Management
            > Stream              : IETF
            > Verifying Party     : IESG
            >
            > _______________________________________________
            > netmod mailing list
            > [e-mail]
            > https://urldefense.com/v3/__https://www.ietf.org/mailman/listinfo/netmod__;!!NEt6yMaO-gk!URK5WVsqD5g7WpzCU1VuzKJA0AUiawXBFLB_gENlsYMrpiMqDtyFoxxyc2_LZA$



    Juniper Business Use Only