Re: [mpls] Last Call: <draft-ietf-mpls-entropy-lsp-ping-04.txt> (Label Switched Path (LSP) and Pseudowire (PW) Ping/Trace over MPLS Network using Entropy Labels (EL)) to Proposed Standard

"Carlos Pignataro (cpignata)" <> Tue, 16 August 2016 02:09 UTC

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From: "Carlos Pignataro (cpignata)" <>
To: "Acee Lindem (acee)" <>
Subject: Re: [mpls] Last Call: <draft-ietf-mpls-entropy-lsp-ping-04.txt> (Label Switched Path (LSP) and Pseudowire (PW) Ping/Trace over MPLS Network using Entropy Labels (EL)) to Proposed Standard
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Hi Acee,

Thanks for the follow-up, please see inline.

On Aug 15, 2016, at 10:04 PM, Acee Lindem (acee) <<>> wrote:

Hi Carlos,

From:  "Carlos Pignataro (cpignata)" <<>>
Date:  Monday, August 15, 2016 at 9:39 PM
To:  Acee Lindem <<>>
Cc:  IETF discussion list <<>>, mpls <<>>,
<<>>, mpls-chairs
Subject:  Re: [mpls] Last Call: <draft-ietf-mpls-entropy-lsp-ping-04.txt>
(Label Switched Path (LSP) and Pseudowire (PW) Ping/Trace over MPLS
Network using Entropy Labels (EL)) to Proposed Standard

Hi, Acee,

On Aug 15, 2016, at 9:02 PM, Acee Lindem (acee) <<>> wrote:

Hi Carlos,

From: mpls <<>> on behalf of "Carlos Pignataro
(cpignata)" <<>>
Date: Monday, August 15, 2016 at 8:24 PM
To: IETF discussion list <<>>
Cc: mpls <<>>, "<>"
mpls-chairs <<>>
Subject: Re: [mpls] Last Call: <draft-ietf-mpls-entropy-lsp-ping-04.txt>
(Label Switched Path (LSP) and Pseudowire (PW) Ping/Trace over MPLS
Network using Entropy Labels (EL)) to Proposed Standard


One outstanding issue with this document is revisiting and getting to a
deliberate position on which RFCs (if any) this document “Updates” (if
approved). Currently:

Updates: 4379, 6424, 6790 (if approved)

The authors, shepherd, chairs, and responsible AD have discussed this
(i.e., which document(s) are actually “Updated" by
draft-ietf-mpls-entropy-lsp-ping-04). We agree that only RFC 6970 is
actually “Updated" by this I-D. The relationship between
RFC 4379, RFC 6424 and draft-ietf-mpls-entropy-lsp-ping is that the the
I-D extends functionality from those “base” RFCs, without updating text
or changing meaning from either.

The draft adds a new multi-path information type to the DDMAP TLV as
defined in RFC 6424. So, why doesn’t it update this RFC as well????

If RFC A defines a TLV space, and RFC B adds one more Type to that TLV,
is that an “Update”?  (???)

Our view is that it is not — it’s a natural extension of a protocol
(defined to be extended by defining new types) but the procedures of the
former are not changed by the existence of the new Type defined in the

Section 1.2 states that the update is applicable to RFC 6424.

It says that RFC 6424 can use the new Multipath Information Type defined.
It does not say that the procedures in RFC 6424 change. (that text can be
updated though)

The RFC 4379 DMAP TLV is definition and procedures are deprecated by RFC

  This document describes methods for performing LSP ping (specified in
  RFC 4379) traceroute over MPLS tunnels and for traceroute of stitched
  MPLS Label Switched Paths (LSPs).  The techniques outlined in RFC
  4379 are insufficient to perform traceroute Forwarding Equivalency
  Class (FEC) validation and path discovery for an LSP that goes over
  other MPLS tunnels or for a stitched LSP.  This document deprecates
  the Downstream Mapping TLV (defined in RFC 4379) in favor of a new
  TLV that, along with other procedures outlined in this document, can
  be used to trace such LSPs.

Exactly. RFC 6424 updated 4379, in a clear way.

However, if this is simply adding a new type w/o changing RFC 6424, then I
would agree with you.

Yes, this draft is adding a new type to the RFC 6424 DDMAP (DSMAP from 4379 is deprecated).

Therefore, this draft does not “update” 6424, but 6424 “updated” 4379.

Does defining a new OSPF RI TLV update RFC4970/7770? (???)

Definitely not.

Exactly, I meant is as (an extreme, for effect) parallel.

As an aside, what constitutes an “Update” could use some more precision,

I agree - this is a recurring debate.

Very much so.


— Carlos.



— Carlos.



— Carlos.

On Aug 12, 2016, at 11:35 AM, The IESG <<>> wrote:

The IESG has received a request from the Multiprotocol Label Switching WG
(mpls) to consider the following document:
- 'Label Switched Path (LSP) and Pseudowire (PW) Ping/Trace over MPLS
Network using Entropy Labels (EL)'
<draft-ietf-mpls-entropy-lsp-ping-04.txt> as Proposed Standard

The IESG plans to make a decision in the next few weeks, and solicits
final comments on this action. Please send substantive comments to the<> mailing lists by 2016-08-26. Exceptionally, comments may be
sent to<> instead. In either case, please retain the
beginning of the Subject line to allow automated sorting.


Multiprotocol Label Switching (MPLS) Label Switched Path (LSP) Ping
and Traceroute are methods used to test Equal-Cost Multipath (ECMP)
paths.  Ping is known as a connectivity verification method and
Traceroute as a fault isolation method, as described in RFC 4379.
When an LSP is signaled using the Entropy Label (EL) described in RFC
6790, the ability for LSP Ping and Traceroute operations to discover
and exercise ECMP paths is lost for scenarios where LSRs apply
different load balancing techniques.  One such scenario is when some
LSRs apply EL-based load balancing while other LSRs apply non-EL
based load balancing (e.g., IP).  Another scenario is when an EL-
based LSP is stitched with another LSP which can be EL-based or non-
EL based.

This document extends the MPLS LSP Ping and Traceroute multipath
mechanisms in RFC 6424 to allow the ability of exercising LSPs which
make use of the EL.  This document updates RFC 4379, RFC 6424, and
RFC 6790.

The file can be obtained via

IESG discussion can be tracked via

The following IPR Declarations may be related to this I-D: