Subject: [mpls] Alvaro Retana's No Objection on draft-ietf-mpls-spring-lsp-ping-11: (with COMMENT)

From: Alvaro Retana <[email-masked]>
Date: Wed, 11 Oct 2017 08:52:25 -0700

Alvaro Retana has entered the following ballot position for
draft-ietf-mpls-spring-lsp-ping-11: No Objection

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COMMENT:
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(1) I’m surprised that there’s not even a passing reference to
draft-ietf-spring-oam-usecase, given that it points to this draft in several
places, among other things as “adding functionality to the use cases described
by this document”.  I'm not advocating for a web of references, just surprised.

(2) The definition of a field with the name “Protocol” in Section 5. (Segment
ID sub-TLV) got me a little confused when I went looking for a registry and
found the values corresponding to the Downstream Detailed Mapping TLV (Section
6).  The name is ok, but I was wondering:  Can you reuse the existing registry
for the values used on the Segment ID sub-TLV?  If so, then the values for
OSPF/ISIS would change.  If not, then please have IANA set one up.

(3) What happens if there’s any error (invalid length, unknown protocol, etc.)
in the sub-TLVs defined in Section 5?  I’m assuming that the action is specific
to the TLV that contains them, or that there is something already specified in
rfc8029 — please include a pointer, or specifics if needed.  I see that Section
7.4. (Segment ID Check) says that other values (for Protocol) “MUST be treated
as Protocol value of 0” — that’s ok for now, but when/if other values are used
this document would have to be Updated.  It may be better to say “any other
unassigned value” (or maybe unrecognized, or something along those lines).

(4) I would really like to see a registry definition for Adj. Type (in 5.3).

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From: "Carlos Pignataro (cpignata)" <[email-masked]>
Date: Wed, 11 Oct 2017 23:50:24 +0000

Hi, Alvaro,

Thanks for the review! Please see inline.

On Oct 11, 2017, at 11:52 AM, Alvaro Retana <[email-masked]<mailto:[email-masked]>> wrote:

Good point and thanks for bringing it up. Will add a small paragraph to the Intro.

Here’s a draft, what do you think?

<t>
The mechanics of MPLS LSP Ping as specified in <xref target="RFC8029" />
can be applied to segment routing networks in a Topology-Aware MPLS
Data plane Path Monitoring System (PMS) as shown in
<xref target="I-D.ietf-spring-oam-usecase" />. This document specifies
Target FEC Stacks to further enhance MPLS LSP Traceroute including
control plane validation and tracing to non-SR-capable notes pointed to
Adj-SIDs.
</t>

I think I understand this — but, the main Section 5 does not include any “Protocol”.

Sections 5.1, 5.2, and 5.3 do. This is a different Protocol, as you gathered, than the one from the Downstream Mapping in Section 6.

So, we cannot reuse the values for the SID sub-TLVs, because those include things like LDP and RSVP.

However, we can set up a registry for S 5.1, 5.2, and 5.3’s protocol. Like this:

9.2.  Protocol in the Segment ID sub-TLV

   IANA is requested to create a new "Protocol in the Segment ID sub-
   TLV" (see Section 5) registry under the "Multi-Protocol Label
   Switching (MPLS) Label Switched Paths (LSPs) Ping Parameters"
   registry.  Code points in the range of 0-250 will be assigned by
   Standards Action.  The range of 251-254 are reserved for experimental
   use and will not be assigned.  The initial entries into the registry
   will be:

     Value           Meaning              Reference
   ----------        ----------------     ------------
     0               Any IGP Protocol     This document
     1               OSPF                 This document
     2               ISIS                 This document

(3) What happens if there’s any error (invalid length, unknown protocol, etc.)
in the sub-TLVs defined in Section 5?  I’m assuming that the action is specific
to the TLV that contains them, or that there is something already specified in
rfc8029 — please include a pointer, or specifics if needed.

Nothing different from RFC 8029, which defines Errored TLVs and procedures.

 I see that Section

Excellent point. Thanks. Will use “unrecognized”.

OK, here it goes:

9.3.  Adjacency Type in the IGP-Adjacency Segment ID

   IANA is requested to create a new "Adjacency Type in the IGP-
   Adjacency Segment ID" (see Section 5.3) registry under the "Multi-
   Protocol Label Switching (MPLS) Label Switched Paths (LSPs) Ping
   Parameters" registry.  Code points in the range of 0-250 will be
   assigned by Standards Action.  The range of 251-254 are reserved for
   experimental use and will not be assigned.  The initial entries into
   the registry will be:

     Value           Meaning
   ----------        ----------------
     0               Unnumbered interface Adjacency
     1               Parallel Adjacency
     4               IPv4, non-parallel Adjacency
     6               IPv6, non-parallel Adjacency

Thanks!

Carlos.