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

[tom petch <[e-mail]>]

----- 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.

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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