Re: [Lsr] draft-ietf-ospf-yang

[Xufeng Liu <[e-mail]>]

Hi Tom,

Thanks for the kind suggestion. We will include these fixes in the next
revision of draft-ietf-teas-yang-te-types.
Best regards,
- Xufeng

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On Wed, Dec 12, 2018 at 7:35 AM tom petch <[e-mail]> wrote:

> ----- Original Message -----
> From: "Xufeng Liu" <[e-mail]>
> Sent: Wednesday, December 12, 2018 4:25 AM
> Subject: Re: draft-ietf-ospf-yang
>
>
> On Tue, Dec 11, 2018 at 7:25 AM tom petch <[e-mail]> wrote:
>
> > ----- Original Message -----
> > From: "Xufeng Liu" <[e-mail]>
> > Sent: Monday, December 10, 2018 2:47 PM
> >
> > Hi Tom,
> >
> > Thanks for checking on this. Agree that we need to fix the description
> > text. What about the following?
> >
> > te-node-id:
> >       A type representing the identifier for a node in a TE topology.
> > The
> > identifier is represented as 32-bit unsigned integer in the
> dotted-quad
> > notation.  This attribute MAY be mapped to the Router Address
> described
> > in
> > Section 2.4.1 of [RFC3630], the TE Router ID described in Section 3 of
> > [RFC6827], the Traffic Engineering Router ID described in Section 4.3
> of
> > [RFC5305], or the TE Router ID described in Section 3.2.1 of
> [RFC6119].
> > The
> > reachability of such a TE node MAY be achieved by a mechanism such as
> > Section 6.2 of [RFC6827].
> >
> > Or, would you give a suggestion?
> >
> > <tp>
> >
> > Looks good.
> >
> > One query I cannot answer; should
> >   RFC5786 Advertising a Router's Local Addresses in OSPF
> >      TE Extensions. R. Aggarwal, K. Kompella. March 2010
> > be there as well?  On the face of it, it looks relevant and would
> appear
> > to meet a need but I note its absence from ospf-yang; I do not know
> how
> > widely it is implemented or used.  This RFC is updated by RFC6827.
>
> RFC6827 uses RFC5786, making it more generic and more complete, I think.
> As you said, RFC6827 has updated RFC5786, which is cited heavily in
> RFC6827. So, logically RFC5786 is already covered. Since RFC5786 does
> not
> provide a TE Router ID mapping by itself, I could not figure out a
> concise
> wording to cite it separately, so I felt that RFC6827 would be more
> relevant. Any suggestion would be appreciated.
>
> <tp>
>
> On reflection, leave it as it is; the text in RFC6827 is, overall,
> clearer than RFC5786.
>
> On an unrelated topic, te-types has references in the YANG module to
> RFC7823 - good - but this RFC does not appear in the References for the
> ID - not so good.  Having added it, you will need a reference to it in
> the text of the I-D lest you get an unused reference.  Common practice
> is to have a section preceding the module along the lines of
> "This module imports [ ..] and references [....].  3.1 has the imports
> but not the references.
>
> And it is expected to have references for imports, e.g.
>      import ietf-inet-types {
>        prefix "inet";
>        reference "RFC 6991 - Common YANG Data Types";
>
> Tom Petch
>
> Thanks,
> - Xufeng
>
> >
> > Tom Petch
> >
> > Thanks,
> > - Xufeng
> >
> > On Fri, Dec 7, 2018 at 12:14 PM tom petch <[e-mail]> wrote:
> >
> > > ----- Original Message -----
> > > From: "Xufeng Liu" <[e-mail]>
> > > Subject: Re: draft-ietf-ospf-yang
> > >
> > >
> > > Hi Acee, Tom, and All,
> > >
> > > Several authors of draft-ietf-teas-yang-te-types had a brief
> > discussion
> > > on
> > > this topic. Our take on the te-node-id and te-router-id is:
> > >
> > > - In TEAS, the te-node-id specified in draft-ietf-teas-yang-te-types
> > has
> > > a
> > > wider use scope than IP MPLS TE. The system may or may not run OSPF
> > TE,
> > > and
> > > may not use IPv4. The 32-bit ID number is used only for uniquely
> > > identifying the TE node, and it may or may not be a routable
> address.
> > > - When RFC3630 is implemented, it is ok to map a routable IPv4
> address
> > > (such as the address of loopbak0) to the te-node-id, but it is not
> > > required.
> > > - We intentionally use the term "te-node-id" instead of
> "te-router-id"
> > > to
> > > convey the concept that this ID is on a TE node, which may or may or
> > be
> > > a
> > > router.
> > > - We will clarify the description to say that "This attribute is MAY
> > be
> > > mapped to TE Router ID in [RFC3630], [RFC5329], [RFC5305], and
> > > [RFC6119]."
> > >
> > > <tp>
> > >
> > > Xufeng
> > >
> > > Thanks for the clarification - I understand better now.
> > >
> > > However, I think that your proposed text is not quite right.
> RFC5329
> > > does not defined a TE Router ID - in fact, I think that that concept
> > is
> > > alien to OSPF.  OSPF has a 32 bit number that is the Router ID with
> no
> > > requirement for that to be a routable address; which is why (IMHO)
> > > RFC5329 defines a
> > > Router IPv6 Address TLV
> > > which carries a routable address (which can meet the needs of TE).
> > >
> > > Likewise, RFC3630, for OSPFv2, does not have the concept of a TE
> > Router
> > > ID; rather, it has a
> > > Router Address TLV
> > > which specifies a stable IP address (which can meet the needs of
> TE).
> > >
> > > And then there is RFC5786 which defines, for OSPF,  the
> > > Node Attribute TLV
> > > with sub-TLV for
> > > Node IPv4 Local Address
> > > Node IPv6 Local Address
> > > allowing for multiple TE addresses for different traffic types.
> > >
> > > I grant you that RFC6119 defines a
> > >  TE Router ID
> > > but the concept is alien to OSPF (IMHO).
> > >
> > > So, if you want to use the term
> > >  TE Router ID
> > > then I think that you will need to explain how that maps onto the
> > > terminology of the existing OSPF RFC.
> > >
> > > Tom Petch
> > >
> > > Thanks,
> > > - Xufeng
> > >
> > > On Thu, Dec 6, 2018 at 12:38 PM Acee Lindem (acee) <[e-mail]>
> > > wrote:
> > >
> > > > Hi Tom,
> > > > I think the only action here is for the authors of
> > > > draft-ietf-teas-yang-te-types to fix their te-node-id definition.
> As
> > > for
> > > > the OSPF Router ID and OSPF/ISIS TE Router IDs we can't change the
> > > decades
> > > > old definitions to achieve uniformity.
> > > > Thanks,
> > > > Acee
> > > >
> > > > On 12/5/18, 11:12 AM, "tom petch" <[e-mail]> wrote:
> > > >
> > > >     ----- Original Message -----
> > > >     From: <[e-mail]>
> > > >     Sent: Wednesday, December 05, 2018 12:57 PM
> > > >
> > > >     > Hi Tom,
> > > >     >
> > > >     > I think that having a different router-id configured per
> > > protocol is
> > > > a
> > > >     matter of deployment. I don't think that we can impose
> anything
> > in
> > > this
> > > >     area. There are use cases where it is good to have separate
> > > router-ids
> > > >     per protocol or instances of a protocol. For instance, when a
> > > router is
> > > >     part of multiple "administrative domains", it is worth having
> > > separate
> > > >     router-ids per admin domain.
> > > >     >
> > > >     > However I have a concern about the router-id or te-node-id
> > > bound to
> > > > a
> > > >     32 bits number only. How do we do in a pure IPv6 network ?
> > > >
> > > >     Stephane
> > > >
> > > >     I am used to configuring a router-id as a 32-bit number with
> no
> > > >     requirement for that to be an address that can be accessed
> over
> > > the
> > > >     internet (so I have always found the idea of 'loopback0'
> > > unfortunate).
> > > >     Yes, the router needs to be addressable, but merging that
> > concept
> > > with
> > > > a
> > > >     router id has always seemed to me unfortunate because they are
> > two
> > > >     separate concepts.  (In fact, I would regard good practice as
> > > giving a
> > > >     router multiple addresses for different functions, so that
> e.g.
> > > syslog
> > > >     can be separated from SNMP or FTP).
> > > >
> > > >     Thus I have no problem with a 32-bit router-id in an IPv6
> > network.
> > > >     Indeed, RFC5329 defines a 32-bit router-id in an OSPFv3
> > > >     Intra-Area-TE-LSA.  It is the Router IPv6 Address TLV that
> > carries
> > > the
> > > >     128-bit address.
> > > >
> > > >     When ospf-yang says
> > > >              container te-rid {
> > > >                if-feature te-rid;
> > > >                description  "Stable OSPF Router IP Address used
> for
> > > Traffic
> > > >                   Engineering (TE)";
> > > >                leaf ipv4-router-id { type inet:ipv4-address;
> > > description
> > > >                    "Explicitly configure the TE IPv4 Router ID.";
> > > >                }
> > > >                leaf ipv6-router-id {
> > > >                  type inet:ipv6-address;
> > > >                  description "Explicitly configure the TE IPv6
> > Router
> > > ID.";
> > > >
> > > >     then that is when I wonder what is going on.  That looks to me
> > > like
> > > >     configuring
> > > >     Router IPv6 Address TLV
> > > >     not the router id.
> > > >
> > > >     Meanwhile, te-yang-te-types has
> > > >
> > > >        te-node-id:
> > > >           A type representing the identifier for a node in a
> > topology.
> > > The
> > > >           identifier is represented as 32-bit unsigned integer in
> > the
> > > >           dotted-quad notation.  This attribute is mapped to
> Router
> > ID
> > > in
> > > >           [RFC3630], [RFC5329], [RFC5305], and [RFC6119].
> > > >
> > > >     Well, I disagree with their choice of YANG type but agree that
> > it
> > > is
> > > >     32-bit and not 128.
> > > >
> > > >     Tom Petch.
> > > >
> > > >     > Brgds,
> > > >     >
> > > >     >
> > > >     > -----Original Message-----
> > > >     > From: tom petch [mailto:[e-mail]]
> > > >     > Sent: Wednesday, December 05, 2018 12:14
> > > >     > To: Acee Lindem (acee); LITKOWSKI Stephane OBS/OINIS;
> > > [e-mail];
> > > >     [e-mail];
> > > [e-mail]
> > > >     > Subject: Re: draft-ietf-ospf-yang
> > > >     >
> > > >     > Acee
> > > >     >
> > > >     > (Top-posting because the indentation usually fails)
> > > >     >
> > > >     > On the TEAS te-types, I had a quick look at where
> > > >     > typedef te-node-id
> > > >     > is used and the answer is lots of places, because it is part
> > of
> > > >     >   grouping explicit-route-hop {
> > > >     >     description    "The explicit route subobject grouping";
> > > >     >     choice type {
> > > >     >       description   "The explicit route subobject type";
> > > >     >       case num-unnum-hop {
> > > >     >         container num-unnum-hop {
> > > >     >           leaf node-id {
> > > >     >             type te-types:te-node-id;
> > > >     >             description   "The identifier of a node in the
> TE
> > > >     > topology.";
> > > >     > and YANG uses of that grouping are many, in several WGs;
> > > however,
> > > >     > because it is a grouping, then the impact of changing the
> type
> > > should
> > > >     be
> > > >     > minimal at least in terms of the I-Ds.
> > > >     >
> > > >     > On the multiple router definitions, my research of the IETF
> > memo
> > > only
> > > >     > came up with the two cited RFC which, to me, say that you
> > should
> > > use
> > > >     an
> > > >     > existing router-id if there is one.
> > > >     >
> > > >     > I did look at the documentation of A Major Router
> Manufacturer
> > > and
> > > >     while
> > > >     > they did not give any advice, the default for a te router-id
> > was
> > > >     > loopback0
> > > >     > while the default for a more general router-id, one without
> > te,
> > > was
> > > >     > loopback0
> > > >     > which gives me the message, you can make them different but
> > > SHOULD
> > > > NOT
> > > >     > (in IETF terminology).
> > > >     >
> > > >     > So while I agree that the two lsr modules should allow
> > > per-protocol
> > > >     > configuration, I think that it should carry a health warning
> > in
> > > the
> > > >     body
> > > >     > of the I-D that this is not a good idea (I struggle to think
> > of
> > > when
> > > >     it
> > > >     > would be a good idea, to use three separate identifiers for,
> > > say, BGP
> > > >     > and the two lsr protocols).
> > > >     >
> > > >     > Tom Petch
> > > >     >
> > > >     > ----- Original Message -----
> > > >     > From: "Acee Lindem (acee)" <[e-mail]>
> > > >     > To: "tom petch" <[e-mail]>;
> > > >     <[e-mail]>;
> > > >     > <[e-mail]>; <[e-mail]>;
> > > >     > <[e-mail]>
> > > >     > Sent: Tuesday, December 04, 2018 7:46 PM
> > > >     >
> > > >     > > Hi Tom,
> > > >     > >
> > > >     > > Let me try to explain.
> > > >     > >
> > > >     > > On 12/4/18, 12:44 PM, "tom petch" <[e-mail]>
> > wrote:
> > > >     > >
> > > >     > >     The router id in this I-D confuse me.
> > > >     > >
> > > >     > >     RFC8294 defines
> > > >     > >          typedef router-id { type yang:dotted-quad;
> > > >     > >
> > > >     > > Some implementations configure a global router-id while
> > others
> > > only
> > > >     > allow it at the control-plane-protocol level. This is why we
> > > have it
> > > >     in
> > > >     > both places.
> > > >     > >
> > > >     > >     ospf-yang defines
> > > >     > >      leaf ipv4-router-id { type inet:ipv4-address;
> > > >     > >
> > > >     > > For better or worse, OSPF has a separate TE address that
> is
> > > > routable
> > > >     > and referred to as the TE router-id. You'll note that this
> is
> > > part of
> > > >     > the te-rid container in both the OSPF and IS-IS YANG models.
> > We
> > > could
> > > >     > add "-te-" to the leaves to avoid confusion.
> > > >     > >
> > > >     > >     draft-ietf-teas-yang-te-types defines
> > > >     > >       typedef te-node-id {     type yang:dotted-quad;
> > > >     > >      ...       This attribute is mapped to Router ID ....
> > > >     > >
> > > >     > > This is just wrong. It is a routable address in the IGP TE
> > > >     extensions.
> > > >     > I've copied the draft authors.
> > > >     > >
> > > >     > > Thanks,
> > > >     > > Acee Lindem
> > > >     > >
> > > >     > >
> > > >     > >     Three different YANG types for a router id.
> > > >     > >
> > > >     > >     Why?
> > > >     > >
> > > >     > >     Behind this, ospf-yang gives as references for a
> router
> > te
> > > id
> > > >     > >     RFC3630(V2) and RFC5329(V3).  Reading these, my take
> is
> > > that a
> > > >     > router id
> > > >     > >     is needed for te but that the existing id should be
> used
> > > where
> > > >     > possible
> > > >     > >     i.e. creating an additional identifier for the same
> > > instance of
> > > >     > the same
> > > >     > >     entity is A Bad Thing (which sounds like a good
> general
> > > >     > principle).
> > > >     > >     With two objects in the lsr protocols, that would
> appear
> > > to
> > > > make
> > > >     > at
> > > >     > >     least three identifiers for the same instance of the
> > same
> > > >     entity.
> > > >     > >
> > > >     > >     Why?
> > > >     > >
> > > >     > >     I copy Stephane on this since the same issues apply to
> > the
> > > > other
> > > >     > lsr
> > > >     > >     protocol, mutatis mutandi.
> > > >     > >
> > > >     > >     Tom Petch
> > > >     > >
> > > >     > >
> > > >     > >
> > > >     > >
> > > >     >
> > > >     >
> > > >     >
> > > >
> > > >
> > >
> >
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