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

[tom petch <[e-mail]>]

----- 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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