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

[tom petch <[e-mail]>]

----- 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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