wdiff draft-ietf-mpls-entropy-lsp-ping-03.txt draft-ietf-mpls-entropy-lsp-ping-04.txt

Internet Engineering Task Force
MPLS Working Group N. Akiya
Internet-Draft Big Switch Networks
Updates: 4379, 6424, 6790 (if approved) G. Swallow
Intended status: Standards Track C. Pignataro
Expires: November 19, 2016 February 12, 2017 Cisco
A. Malis
Huawei Technologies
S. Aldrin
Google
May 18,
August 11, 2016

Label Switched Path (LSP) and Pseudowire (PW) Ping/Trace over
MPLS Network using Entropy Labels (EL)
draft-ietf-mpls-entropy-lsp-ping-03
draft-ietf-mpls-entropy-lsp-ping-04

Abstract

The

Multiprotocol Label Switching (MPLS) Label Switched Path (LSP) Ping
and Traceroute are methods used to exercise specific paths of test Equal-Cost Multipath (ECMP). (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 to use using the Entropy Label (EL) described in RFC
6790, the ability for LSP Ping and Traceroute
operation operations to discover
and exercise ECMP paths has been is lost in for scenarios which where LSRs apply deviating
different load balance balancing techniques. One such scenario is when some
LSRs apply EL based EL-based load balancing while other LSRs apply non-EL
based load balancing (ex: (e.g., IP). Another scenario is when EL an EL-
based LSP is stitched with another LSP which can be EL based EL-based or non-EL non-
EL based.

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

Requirements Language

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].

Status of This Memo

This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.

Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."

This Internet-Draft will expire on November 19, 2016. February 12, 2017.

This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.

Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Prerequisite . . . . . . . . . . . . . . . . . . . . . . 4
1.3. Background . . . . . . . . . . . . . . . . . . . . . . . 4
2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Multipath Type 9 . . . . . . . . . . . . . . . . . . . . . . 7
4. Pseudowire Tracing . . . . . . . . . . . . . . . . . . . . . 7
5. Initiating LSR Procedures Entropy Label FEC . . . . . . . . . . . . . . . . . . 8
6. Responder LSR Procedures . . . . 8
6. DS Flags: L and E . . . . . . . . . . . . . . 9
6.1. IP Based Load Balancer & Not Pushing ELI/EL . . . . . . . 10
6.2. IP Based Load Balancer & Pushes ELI/EL . 9
7. New Multipath Information Type: TBD4 . . . . . . . . 11
6.3. Label Based Load Balancer & Not Pushing ELI/EL . . . . 10
8. Initiating LSR Procedures . 12
6.4. Label Based Load Balancer & Pushes ELI/EL . . . . . . . . 12
6.5. Flow Aware MS-PW Stitching LSR . . . . . . . . . 11
9. Responder LSR Procedures . . . . 13
7. Entropy Label FEC . . . . . . . . . . . . . . 13
9.1. IP Based Load Balancer & Not Pushing ELI/EL . . . . . . . 14
9.2. IP Based Load Balancer & Pushes ELI/EL . 13
8. DS Flags: L and E . . . . . . . . 14
9.3. Label Based Load Balancer & Not Pushing ELI/EL . . . . . 15
9.4. Label Based Load Balancer & Pushes ELI/EL . . . . . . . . 16
9.5. Flow-Aware MS-PW Stitching LSR . 14
9. New Multipath Information Type: TBD4 . . . . . . . . . . . . 15 17
10. Supported and Unsupported Cases . . . . . . . . . . . . . . . 16 17
11. Security Considerations . . . . . . . . . . . . . . . . . . . 18 19
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
12.1. DS Flags . . Entropy Label FEC . . . . . . . . . . . . . . . . . . . 19
12.2. DS Flags . . . 19
12.2. Multpath Type . . . . . . . . . . . . . . . . . . . . . 19
12.3. Entropy Label FEC Multipath Type . . . . . . . . . . . . . . . . . . . 19 . . 20
13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 19 20
14. Contributing Authors . . . . . . . . . . . . . . . . . . . . 20
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 20
15.1. Normative References . . . . . . . . . . . . . . . . . . 20
15.2. Informative References . . . . . . . . . . . . . . . . . 20 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21

1. Introduction

1.1. Terminology

The following acronyms/terminologies acronyms and terms are used in this document:

o MPLS - Multiprotocol Label Switching.

o LSP - Label Switched Path.

o LSR - Label Switching Router.

o FEC - Forwarding Equivalent Class.

o ECMP - Equal-Cost Multipath.

o EL - Entropy Label.

o ELI - Entropy Label Indicator.

o GAL - Generic Associated Channel Label.

o MS-PW - Multi-Segment Pseudowire.

o Initiating LSR - LSR which sends an MPLS echo request.

o Responder LSR - LSR which receives an MPLS echo request and sends
an MPLS echo reply.

o IP Based IP-Based Load Balancer - LSR which load balances on fields from an
IP header (and possibly fields from upper layers), and does not
consider an entropy label from an MPLS label stack (i.e. Flow Label (i.e., flow
label [RFC6391] or
Entropy Label) entropy label [RFC6790]) for load balancing purpose.
purposes.

o Label Based Label-Based Load Balancer - LSR which load balances on an entropy
label from an MPLS label stack (i.e. Flow Label (i.e., flow label or Entropy Label), entropy
label), and does not consider fields from an IP header (and
possibly fields from upper layers) for load balancing purpose. purposes.

o Label and IP Based IP-Based Load Balancer - LSR which load balances on both
entropy labels from an MPLS label stack (including Flow Label or Entropy Label if
present) and fields from an IP
header (and possibly fields from upper layers).

1.2. Prerequisite Background

MPLS implementations employ a wide variety of load balancing
techniques in terms of fields used for hash "keys". The mechanisms
in [RFC4379] and updated by [RFC6424] are designed to provide
multipath support for a subset of techniques. Intent The intent of this
document is to restore provide multipath support for those the supported techniques
which have been are compromised by the introduction use of [RFC6790] (i.e. Entropy Labels). ELs [RFC6790]. Section 10
describes supported and unsupported cases, and it may be useful for one
the reader to visit first review this section first.

1.3. Background

Section 3.3.1 of [RFC4379] specifies multipath information encoding
in Downstream Mapping (DSMAP) TLV (Section 3.3 of [RFC4379]) and section.

The Downstream Detailed Mapping (DDMAP) TLV (Section 3.3 of [RFC6424]) [RFC6424] provides
multipath information which can be used by an LSP Ping initiator to
trace and validate all ECMP paths between an ingress and egress. While the multipath
information encoding is common to both the Downstream Mapping (DSMAP)
TLV and the Downstream Detailed Mapping (DDMAP) TLV, the former has
been deprecated by [RFC6424] and this specification only concerns
itself with the latter. The
multipath information encodings defined by [RFC6424] are sufficient
when all the LSRs along the path(s), between ingress and egress,
consider the same set of "keys" as input for load balancing
algorithm:
algorithms, e.g. either all IP based IP-based or all label based. label-based.

With the introduction of [RFC6790], it is quite normal to see set of some LSRs
performing may perform load
balancing based on EL/ELI labels while others still follow
the traditional way (IP based). may be IP-based. This results
in an LSP Ping initiator to not be able to trace and validate all the
ECMP paths in the following scenarios:

o One or more transit LSRs along an LSP with ELI/EL in label stack
do not perform ECMP load balancing based on EL (hashes based on
"keys" including the IP destination address). This scenario is
not only possible but quite common due to transit LSRs not
implementing [RFC6790] or transit LSRs implementing [RFC6790] [RFC6790], but
not implementing the suggested transit LSR behavior in Section 4.3
of [RFC6790].

o Two or more LSPs stitched together with at least one of these LSP LSPs
pushing ELI/EL in into the label stack. Such scenarios are described in
[I-D.ravisingh-mpls-el-for-seamless-mpls].

These scenarios will can be quite common because every deployment deployments of [RFC6790] will invariably end up with
typically have a mixture of nodes that support ELI/EL and nodes that
do not. There will also typically be a mixture of areas that support
ELI/EL and areas that do not.

As pointed out in [RFC6790] [RFC6790], the procedures of [RFC4379] (and
consequently of [RFC6424]) with respect to multipath information type
{9} are incomplete. However However, [RFC6790] does not actually update
[RFC4379]. Further Further, the specific EL location is not clearly defined,
particularly in the case of Flow Aware Pseudowires [RFC6391]. This
document defines a new FEC Stack sub-TLV for the Entropy Label. entropy label.
Section 3 of this document updates the procedures for multipath
information type {9} described in [RFC4379] and applicable to
[RFC6424]. The rest of this document describes extensions required
to restore ECMP discovery and tracing capabilities for the scenarios
described.

[RFC4379], [RFC6424], and this document will support IP-based load
balancers and label-based load balancers which limit their hash to
the first (top-most) or only entropy label in the label stack. Other
use cases (refer to Section 10) are out of scope.

2. Overview

[RFC4379] describes LSP traceroute as an operation where the
initiating LSR send sends a series of MPLS echo requests towards the same
destination. The first packet in the series have has the TTL set to 1.
When the echo reply is received from the LSR one hop away away, the second
echo request in the series is sent with the TTL set to 2, for 2. For each
additional echo request the TLL is incremented by one until a
response is received from the intended destination. Initiating The initiating
LSR discovers and exercises ECMP by obtaining multipath information
from each transit LSR and using a specific destination IP address or
specific entropy label.

Notion of

From here on, the notation {x, y, z} from here on refers to Multipath multipath information
types x, y or z. Multipath information types are defined in
Section 3.3 of [RFC4379].

The LSR initiating LSP Ping initiating LSR sends an MPLS echo request with multipath
information. This multipath information is described in the echo
request's DDMAP TLV of
echo request, TLV, and may contain a set of IP addresses or a set
of labels. Multipath information types {2, 4, 8} carry a set of IP addresses
addresses, and multipath information type {9} carries a set of
labels. Responder The responder LSR
(receiver (the receiver of the MPLS echo request)
will determine the subset of
initiator specified initiator-specified multipath
information which load balances to each downstream (outgoing
interface). Responder The responder LSR sends an MPLS echo reply with
resulting multipath information per downstream (outgoing interface)
back to the initiating LSR. Initiating The initiating LSR is then able to use a
specific IP destination address or a specific label to exercise a
specific ECMP path on the responder LSR.

Current behavior is problematic in following scenarios:

o Initiating The initiating LSR sends IP multipath information, but the
responder LSR load balances on labels.

o Initiating The initiating LSR sends label multipath information, but the
responder LSR load balances on IP addresses.

o Initiating The initiating LSR sends existing multipath information to an LSR
which pushes ELI/EL in the label stack, but the initiating LSR can
only continue to discover and exercise specific path paths of the ECMP,
if the LSR which pushes ELI/EL responds with both IP addresses and
the associated EL corresponding to each IP address. This is
because:

* An ELI/EL pushing LSR that is a stitching point will load
balance based on the IP address.

* Downstream LSR(s) of an ELI/EL pushing LSR may load balance
based on ELs.

o Initiating The initiating LSR sends one of existing multipath information to an ELI/
EL pushing LSR, but the initiating LSR can only continue to
discover and exercise specific path paths of ECMP ECMP, if the ELI/EL
pushing LSR responds with both labels and associated EL
corresponding to the label. This is because:

* An ELI/EL pushing LSR that is a stitching point will load
balance based on EL from the previous LSP and pushes a new EL.

* Downstream LSR(s) of ELI/EL pushing LSR may load balance based
on new ELs.

The above scenarios point to how demonstrate the existing multipath information is
insufficient when LSP traceroute is operated used on an LSP with
Entropy Labels described by entropy
labels [RFC6790]. Therefore, this This document defines a new multipath information
type to be used in the DDMAP of MPLS echo request/reply packets in Section 9.

In addition, for
[RFC6790] LSPs.

The responder LSR can reply with empty multipath information if no IP
address is set or label set from is received with the multipath information
matched load balancing to a downstream. Empty
information. An empty return is also possible if an initiating LSR
sends multipath information of one type, IP address or label, but the
responder LSR load balances on the other type. To disambiguate
between the two results, this document introduces new flags in the
DDMAP TLV to allow the responder LSR to describe the load balance balancing
technique being used.

It is required that all

All LSRs along the LSP need to be able to understand the new flags as
well as
and the new multipath information type. It is also required that the
initiating LSR can select both the IP destination address and label
to use on when transmitting MPLS echo request packets. Two additional
DS Flags are defined for the DDMAP TLV in Section 8. 6. These two flags
are used by the responder LSR to describe its load balance behavior
on a received MPLS echo request.

Note that the terms "IP Based Load Balancer", "Label Based "IP-Based Load Balancer" and "Label Based "Label-Based Load
Balancer" are in context of how a received MPLS echo request is
handled by the responder LSR.

3. Multipath Type 9

This section defines to which labels multipath type {9} applies.

[RFC4379] defined multipath type {9} for tracing of LSPs where label
based load-balancing load balancing is used. However, as pointed out in [RFC6790],
the procedures for using this type are incomplete as the specific
location of the label was not defined. It was assumed that the
presence of multipath type {9} implied the value of the bottom-of-
stack label should be varied by the values indicated by multipath to
determine their the respective out-going outgoing interfaces.

Section 7 5 defines a new FEC-Stack sub-TLV to indicate an entropy
label. These labels may MAY appear anywhere in a label stack.

Multipath type {9} applies to the first label in the label-stack label stack that
corresponds to an EL-FEC. If no such label is found, it applies to
the label at the bottom of the label stack.

4. Pseudowire Tracing

This section defines procedures for tracing pseudowires. These
procedures pertain to the use of multipath information type {9} as
well as type {TBD4}. In all cases below, when a control word is in
use
use, the N-flag in the DDMAP MUST be set. Note that when a control
word is not in use use, the returned DDMAPs may not be accurate.

In order to trace a non Flow-Aware Pseudowire non-flow-aware Pseudowire, the initiator includes
an EL-FEC instead of the appropriate PW-FEC at the bottom of the FEC-
Stack. FEC
stack. Tracing in this way will cause compliant routers to return
the proper outgoing interface. Note that this procedure only traces
to the end of the MPLS LSP that is under test and will not verify the
PW FEC. To actually verify the PW-FEC PW FEC or in the case of a MS-PW, to
determine the next pseudowire label value, the initiator MUST repeat
that step of the trace, trace (i.e., repeating the TTL value used) but with
the FEC-Stack FEC Stack modified to contain the appropriate PW-FEC. PW FEC. Note that
these procedures are applicable to scenarios which where an initiator is
able to vary the bottom label (i.e. pseudowire (i.e., Pseudowire label). Possible
scenarios are tracing multiple non Flow-Aware non-flow-aware Pseudowires on the same
endpoints or tracing a non Flow-Aware non-flow-aware Pseudowire provisioned with
multiple pseudowire Pseudowire labels.

In order to trace a Flow Aware Pseudowire, flow-aware Pseudowire [RFC6391], the initiator
includes an
EL-FEC EL FEC at the bottom of the FEC-Stack FEC Stack and pushes the
appropriate PW- PW FEC onto the FEC-Stack. FEC Stack.

In order to trace through non-compliant routers routers, the initiator forms
an MPLS echo request message and includes a DDMAP with multipath type
{9}. For a non Flow-Aware non-flow-aware Pseudowire it includes the appropriate PW- PW
FEC in the FEC-Stack. FEC Stack. For a Flow Aware flow-aware Pseudowire, the initiator
includes a NIL-FEC Nil FEC at the bottom of the FEC-Stack FEC Stack and pushes the
appropriate PW-FEC PW FEC onto the FEC-Stack. FEC Stack.

5. Initiating LSR Procedures

In order to facilitate the flow of the following text we speak in
terms of Entropy Label FEC

The entropy label indicator (ELI) is a boolean called EL_LSP maintained by the initiating LSR.
This reserved label that has no
explicit FEC associated, and has label value controls 7 assigned from the multipath information type
reserved range. Use the Nil FEC as the Target FEC Stack sub-TLV to be used
account for ELI in
transmitted echo request packets. When a Target FEC Stack TLV.

The entropy label (EL) is a special purpose label with the initiating LSR label
value being discretionary (i.e., the label value is
transmitting not from the
reserved range). For LSP verification mechanics to perform its
purpose, it is necessary for a Target FEC Stack sub-TLV to clearly
describe the EL, particularly in the scenario where the label stack
does not carry ELI (e.g., flow-aware Pseudowire [RFC6391]).
Therefore, this document defines an echo request packet with DDMAP with EL FEC sub-TLV (TBD1, see
Section 12.1) to allow a non-zero
multipath information type, then EL_LSP boolean MUST Target FEC Stack sub-TLV to be consulted added to
determine the multipath information type to use.

In addition
Target FEC Stack to procedures described in [RFC4379] account for EL.

The Length is 4. Labels are 20-bit values treated as updated by
Section numbers.

0 1 2 3 and [RFC6424], initiating LSR MUST operate with following
procedures.

o When
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label | MBZ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 1: Entropy Label FEC

Label is the initiating LSR pushes ELI/EL, initialize EL_LSP=True.
Else set EL_LSP=False.

o When actual label value inserted in the initiating LSR is transmitting non-zero multipath
information type:

* If (EL_LSP), label stack; the initiating LSR MBZ
field MUST use multipath information
type {TBD4} unless same responder LSR cannot handle type
{TBD4}. When the initiating LSR is transmitting multipath
information type {TBD4} in this case, both "IP Multipath
Information" be zero when sent and "Label Multipath Information" ignored on receipt.

6. DS Flags: L and E

Two flags, L and E, are added to the DS Flags field of the DDMAP TLV.
Both flags MUST NOT be
included, set in echo request packets when sending, and "IP Associated Label Multipath Information"
SHOULD be ignored when received. Zero, one or both new flags MUST be omitted (NULL).

* Else
set in echo reply packets.

DS Flags
--------

0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
| MBZ |L|E|I|N|
+-+-+-+-+-+-+-+-+

RFC-Editor-Note: Please update the initiating LSR MAY use multipath information type {2,
4, 8, 9, TBD4}. When above figure to place the initiating LSR is transmitting
multipath information type {TBD4} flag E
in this case, "IP Multipath
Information" MUST be included, the bit number TBD2 and "Label Multipath
Information" the flag L in the bit number TBD3.

Flag Name and "IP Associated Label Multipath Information" Meaning
---- ----------------
L Label-based load balance indicator
This flag MUST be omitted (NULL).

o When set to zero in the initiating LSR receives echo reply with {L=0, E=1} in DS
flags with valid contents, request. An LSR
which performs load balancing on a label MUST set EL_LSP=True.

In following conditions, this
flag in the initiating echo reply. An LSR may have lost which performs load
balancing on IP MUST NOT set this flag in the ability echo
reply.

E ELI/EL push indicator
This flag MUST be set to exercise specific ECMP paths. The initiating LSR MAY continue
with "best effort".

o Received zero in the echo reply contains empty multipath information.

o Received request. An LSR
which pushes ELI/EL MUST set this flag in the echo reply contains {L=0, E=<any>} DS flags, but
reply. An LSR which does not
contain IP multipath information.

o Received push ELI/EL MUST NOT set
this flag in the echo reply contains {L=1, E=<any>} DS flags, but does not
contain label multipath information.

o Received reply.

The two flags result in four load balancing techniques which the echo
reply contains {L=<any>, E=1} DS flags, but generating LSR can indicate:

o {L=0, E=0} LSR load balances based on IP and does not
contain associated label multipath information. push ELI/EL.

o {L=0, E=1} LSR load balances based on IP multipath information types {2, 4, 8} sent, and received echo
reply with pushes ELI/EL.

o {L=1, E=0} in DS flags. LSR load balances based on labels and does not push
ELI/EL.

o {L=1, E=1} LSR load balances based on labels and pushes ELI/EL.

7. New Multipath Information Type: TBD4

One new multipath information type {TBD4} sent, and received echo reply
with is added to be used in DDMAP TLV.
This new multipath information type other than {TBD4}.

6. Responder LSR Procedures

Common Procedures:

o The responder LSR receiving an MPLS echo request packet MUST first
determine whether or not has the initiating LSR supports this LSP Ping value of TBD4.

Key Type Multipath Information
--- ---------------- ---------------------
TBD4 IP and Traceroute extension for Entropy Labels. If either label set IP addresses and label prefixes

Multipath type TBD4 is comprised of three sections. The first
section describes the
following conditions are met, the responder LSR SHOULD determine
that IP address set. The second section describes
the initiating LSR supports this LSP Ping and Traceroute
extension for Entropy Labels.

1. Received MPLS echo request contains the multipath information
type {TBD4}.

2. Received MPLS echo request contains a Target FEC Stack TLV
that includes the Entropy Label FEC.

If the initiating LSR is determined to not support this LSP Ping
and Traceroute extension for Entropy Labels, then the responder
LSR MUST NOT follow further procedures described in this section.
Specifically, MPLS echo reply packets:

* MUST have following DS Flags cleared (i.e., not set): "ELI/EL
push indicator" and "Label based load balance indicator".

* MUST NOT use multipath information type {TBD4}.

o The responder LSR receiving an MPLS echo request packet with
multipath information type {TBD4} MUST validate following
contents. Any deviation MUST result in the responder LSR to
consider the packet as malformed and return code 1 (Malformed echo
request received) in the MPLS echo reply packet.

* IP multipath information MUST be included.

* Label multipath information MAY be included.

* IP associated label multipath information MUST be omitted
(NULL).

Following subsections describe expected responder LSR procedures when
echo reply is to include DDMAP TLVs, based on local load balance
technique being employed. In case the responder LSR performs
deviating load balance techniques per downstream basis, appropriate
procedures matching to each downstream load balance technique MUST be
operated.

6.1. IP Based Load Balancer & Not Pushing ELI/EL

o The responder MUST set {L=0, E=0} in DS flags.

o If multipath information type {2, 4, 8} is received, the responder
MUST comply with [RFC4379] and [RFC6424].

o If multipath information type {9} is received, the responder MUST
reply with multipath type {0}.

o If multipath information type {TBD4} is received, following
procedures are to be used:

* The responder MUST reply with multipath information type
{TBD4}.

* "Label Multipath Information" and "Associated Label Multipath
Information" sections MUST be omitted (NULL).

* If no matching IP address is found, then "IPMultipathType"
field MUST be set to multipath information type {0} and "IP
Multipath Information" section MUST also be omitted (NULL).

* If at least one matching IP address is found, then
"IPMultipathType" field MUST be set to appropriate multipath
information type {2, 4, 8} and "IP Multipath Information"
section MUST be included.

6.2. IP Based Load Balancer & Pushes ELI/EL

o The responder MUST set {L=0, E=1} in DS flags.

o If multipath information type {9} is received, the responder MUST
reply with multipath type {0}.

o If multipath type {2, 4, 8, TBD4} is received, following
procedures are to be used:

* label set. The responder MUST respond with multipath type {TBD4}. See
Section 9 for details of multipath type {TBD4}.

* "Label Multipath Information" third section MUST be omitted (i.e. is
it not there).

* describes another label set which
associates to either the IP address set or the label set specified in received IP multipath information
MUST be used to determine
the returning IP/Label pairs.

* If received multipath information type was {TBD4}, received
"Label other sections.

Multipath Information" sections MUST NOT be used to
determine the associated label portion of returning IP/Label
pairs.

* If no matching IP address is found, then "IPMultipathType"
field MUST be set to multipath information type {0} and "IP TBD4 has following format:

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|IPMultipathType| IP Multipath Information" section MUST be omitted. In addition,
"Assoc Length | Reserved(MBZ) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ~
| (IP Multipath Information) |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|LbMultipathType| Label Multipath Length" MUST be set to 0, and
"Associated Length | Reserved(MBZ) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ~
| (Label Multipath Information) |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Assoc Label Multipath Length | Reserved(MBZ) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ~
| (Associated Label Multipath Information) |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 2: Multipath Information Type TBD4

o IPMultipathType

* 0 when "IP Multipath Information" section MUST also be is omitted.

* If at least Otherwise, one matching
of the IP multipath information values: {2, 4, 8}.

o IP address Multipath Information
* This section is found, then omitted when "IPMultipathType" field MUST be set to appropriate is 0.
Otherwise, this section reuses IP multipath information type from
[RFC4379]. Specifically, multipath information for values {2,
4, 8} and "IP can be used.

o LbMultipathType

* 0 when "Label Multipath Information"
section MUST be included. In addition, "Associated is omitted. Otherwise,
label multipath information value {9}.

o Label Multipath Information" Information

* This section MUST is omitted when "LbMultipathType" is 0.
Otherwise, this section reuses label multipath information from
[RFC4379]. Specifically, multipath information for value {9}
can be populated with list of
labels corresponding to each IP address specified in "IP used.

o Associated Label Multipath Information" section. Information

* "Assoc Label Multipath Length"
MUST be set to is a value representing 16 bit field of multipath
information which indicates the length in octets of the
associated label multipath information.

* "Associated Label Multipath Information" field.

6.3. Label Based Load Balancer & Not Pushing ELI/EL

o The responder MUST set {L=1, E=0} in DS flags.

o If multipath information type {2, 4, 8} is received, the responder
MUST reply a list of labels
with multipath type {0}.

o If multipath information type {9} is received, the responder each label described in 24 bits. This section MUST
comply with [RFC4379] and [RFC6424] as updated by Section 3.

o If multipath information type {TBD4} is received, following
procedures are to be used:

* The responder MUST
omitted in an MPLS echo request message. A midpoint which
pushes ELI/EL labels SHOULD include "Assoc Label Multipath
Information" in its MPLS echo reply message, along with multipath information type
{TBD4}.

* either
"IP Multipath Information" or "Label Multipath Information".
Each specified associated label described in this section maps
to a specific IP address OR label described in the "IP
Multipath Information" and "Associated Label section or "Label Multipath Information" sections
section. For example, if three IP addresses are specified in
the "IP Multipath Information" section, then there MUST be omitted (NULL).

* If no matching
three labels described in this section. The first label maps
to the first IP address specified, the second label maps to the
second IP address specified, and the third label maps to the
third IP address specified.

When a section is found, then "LbMultipathType" field omitted, the length for that section MUST be BE set to
zero.

8. Initiating LSR Procedures

The following procedure is described in terms of an EL_LSP boolean
maintained by the initiating LSR. This value controls the multipath
information type {0} and "Label
Multipath Information" section MUST also to be omitted (NULL).

* If at least one matching label used in the transmitted echo request packets.
When the initiating LSR is found, transmitting an echo request packet with
DDMAP with a non-zero multipath information type, then "LbMultipathType"
field the EL_LSP
boolean MUST be set consulted to appropriate determine the multipath information type {9}
to use.

In addition to procedures described in [RFC4379], as updated by
Section 3 and "Label Multipath Information" section [RFC6424], the initiating LSR MUST be included.

6.4. Label Based Load Balancer & Pushes ELI/EL operate with the
following procedures:

o The responder MUST When the initiating LSR pushes ELI/EL, initialize EL_LSP=True.
Else set {L=1, E=1} in DS flags. EL_LSP=False.

o If multipath information type {2, 4, 8} is received, When the responder
MUST reply with multipath type {0}.

o If multipath type {9, TBD4} initiating LSR is received, following procedures are
to be used: transmitting a non-zero multipath
information type:

* The responder If (EL_LSP), the initiating LSR MUST respond with use multipath information
type {TBD4} unless the responder LSR cannot handle type {TBD4}.

*
When the initiating LSR is transmitting multipath information
type {TBD4}, both "IP Multipath Information" section and "Label
Multipath Information" MUST be omitted.

* included, and "IP Associated
Label set specified in received label multipath information Multipath Information" MUST be used to determine the returning Label/Label pairs. omitted (NULL).

* If received Else the initiating LSR MAY use multipath information type was {TBD4}, received
"Label Multipath Information" sections MUST NOT be used to
determine {2,
4, 8, 9, TBD4}. When the associated label portion of returning Label/Label
pairs.

* If no matching label initiating LSR is found, then "LbMultipathType" field
MUST be set to transmitting
multipath information type {0} and "Label {TBD4} in this case, "IP Multipath
Information" section MUST be omitted. In addition,
"Assoc Label included, and "Label Multipath Length" MUST be set to 0,
Information" and
"Associated "IP Associated Label Multipath Information" section MUST also be
omitted.

* If at least one matching label is found, then "LbMultipathType"
field
MUST be omitted (NULL).

o When the initiating LSR receives echo reply with {L=0, E=1} in DS
flags with valid contents, set EL_LSP=True.

In the following conditions, the initiating LSR may have lost the
ability to appropriate exercise specific ECMP paths. The initiating LSR MAY
continue with "best effort" in the following cases:

o Received echo reply contains empty multipath information.

o Received echo reply contains {L=0, E=<any>} DS flags, but does not
contain IP multipath information.

o Received echo reply contains {L=1, E=<any>} DS flags, but does not
contain label multipath information.

o Received echo reply contains {L=<any>, E=1} DS flags, but does not
contain associated label multipath information.

o IP multipath information type {9} types {2, 4, 8} sent, and "Label Multipath Information" section MUST be included. In
addition, "Associated Label Multipath Information" section MUST
be populated received echo
reply with list of labels corresponding to each label
specified in "Label Multipath Information" section. "Assoc
Label Multipath Length" MUST be set to a value representing
length in octets of "Associated Label Multipath Information"
field.

6.5. Flow Aware MS-PW Stitching LSR

Stitching LSR that cross-connects Flow Aware Pseudowires behave {L=1, E=0} in
one of two ways: DS flags.

o Load balances on previous Flow Label, Multipath information type {TBD4} sent, and carries over same Flow
Label. For this case, stitching received echo reply
with multipath information type other than {TBD4}.

9. Responder LSR is to behave as procedures
described in Section 6.3. Procedures

Common Procedures:

o Load balances on previous Flow Label, and replaces Flow Label with
newly computed. For this case, stitching The responder LSR is to behave as
procedures described in Section 6.4.

7. Entropy Label FEC

Entropy Label Indicator (ELI) is a reserved label that has no
explicit FEC associated, and has label value 7 assigned from receiving an MPLS echo request packet MUST first
determine whether or not the
reserved range. Use Nil FEC as Target FEC Stack sub-TLV to account initiating LSR supports this LSP Ping
and Traceroute extension for ELI in a Target FEC Stack TLV. Entropy Label (EL) is a special purpose label with label value being
discretionary (i.e. label value may not be from Labels. If either of the reserved range).
For
following conditions are met, the responder LSR SHOULD determine
that the initiating LSR supports this LSP verification mechanics to perform its purpose, it is
necessary Ping and Traceroute
extension for entropy labels.

1. Received MPLS echo request contains the multipath information
type {TBD4}.

2. Received MPLS echo request contains a Target FEC Stack sub-TLV to clearly describe EL,
particularly in TLV
that includes the scenario where entropy label stack does not carry ELI
(ex: Flow Aware Pseudowire [RFC6391]). Therefore, this document
defines a EL FEC to allow a Target FEC Stack sub-TLV to be added to FEC.

If the Target FEC Stack initiating LSR is determined to account not support this LSP Ping
and Traceroute extension for EL.

The Length is 4. Labels are 20-bit values treated as numbers.

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label | MBZ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 1: Entropy Label FEC

Label is entropy labels, then the actual label value inserted responder
LSR MUST NOT follow further procedures described in the label stack; the MBZ
fields this section.
Specifically, MPLS echo reply packets:

* MUST be zero when sent and ignored on receipt.

8. have following DS Flags: L Flags cleared (i.e., not set): "ELI/EL
push indicator" and E

Two flags, L "Label-based load balance indicator".

* MUST NOT use multipath information type {TBD4}.

o The responder LSR receiving an MPLS echo request packet with
multipath information type {TBD4} MUST validate the following
contents. Any deviation MUST result in the responder LSR to
consider the packet as malformed and E, are added return code 1 ("Malformed
echo request received") in DS Flags field of the DDMAP TLV.
Both flags MPLS echo reply packet.

* IP multipath information MUST NOT be set in echo request packets when sending, and
ignored when received. Zero, one or both new flags included.

* Label multipath information MAY be included.

* IP associated label multipath information MUST be set in omitted
(NULL).

The following subsections describe expected responder LSR procedures
when the echo reply packets.

DS Flags
--------

0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
| MBZ |L|E|I|N|
+-+-+-+-+-+-+-+-+

RFC-Editor-Note: Please update above figure is to place include DDMAP TLVs, based on the flag E local load
balance technique being employed. In case the responder LSR performs
deviating load balance techniques on a per downstream basis,
appropriate procedures matched to each downstream load balance
technique MUST be followed.

9.1. IP Based Load Balancer & Not Pushing ELI/EL

o The responder MUST set {L=0, E=0} in DS flags.

o If multipath information type {2, 4, 8} is received, the bit number TBD2 responder
MUST comply with [RFC4379] and [RFC6424].

o If multipath information type {9} is received, the flag L in responder MUST
reply with multipath type {0}.

o If multipath information type {TBD4} is received, the bit number TBD3.

Flag Name following
procedures are to be used:

* The responder MUST reply with multipath information type
{TBD4}.

* The "Label Multipath Information" and Meaning
---- ----------------
L "Associated Label based load balance indicator
This flag
Multipath Information" sections MUST be set to zero in the echo request. LSR
which performs load balancing on a label omitted (NULL).

* If no matching IP address is found, then the "IPMultipathType"
field MUST be set this
flag in to multipath information type {0} and the echo reply. LSR which performs load
balancing on IP "IP
Multipath Information" section MUST NOT set this flag in also be omitted (NULL).

* If at least one matching IP address is found, then the echo
reply.

E ELI/EL push indicator
This flag
"IPMultipathType" field MUST be set to zero in appropriate multipath
information type {2, 4, 8} and the echo request. LSR
which pushes ELI/EL "IP Multipath Information"
section MUST set this flag in the echo
reply. LSR which does not push be included.

9.2. IP Based Load Balancer & Pushes ELI/EL

o The responder MUST NOT set
this flag {L=0, E=1} in DS flags.

o If multipath information type {9} is received, the echo reply.

Two flags result in four load balancing techniques which echo responder MUST
reply
generating LSR can indicate: with multipath type {0}.

o {L=0, E=0} LSR load balances based on IP and does If multipath type {2, 4, 8, TBD4} is received, the following
procedures are to be used:

* The responder MUST respond with multipath type {TBD4}. See
Section 7 for details of multipath type {TBD4}.

* The "Label Multipath Information" section MUST be omitted
(i.e., it is not push ELI/EL.

o {L=0, E=1} LSR load balances based on there).

* The IP address set specified in the received IP and pushes ELI/EL.

o {L=1, E=0} LSR load balances based on label and does not push ELI/
EL.

o {L=1, E=1} LSR load balances based on label and pushes ELI/EL.

9. New Multipath Information Type: TBD4

One new multipath
information type is added to MUST be used in DDMAP TLV.
New to determine the returning IP/Label
pairs.

* If the received multipath information type has value of TBD4.

Key Type was {TBD4}, the
received "Label Multipath Information
--- ---------------- ---------------------
TBD4 IP and label set IP addresses and Information" sections MUST NOT be
used to determine the associated label prefixes

Multipath type TBD4 is comprised portion of three sections. One section to
describe returning IP/
Label pairs.

* If no matching IP address set. One section is found, then the "IPMultipathType"
field MUST be set to describe label set. One multipath information type {0} and the "IP
Multipath Information" section to describe another label MUST be omitted. In addition,
the "Assoc Label Multipath Length" MUST be set which associates to either 0, and the
"Associated Label Multipath Information" section MUST also be
omitted.

* If at least one matching IP address set or label set specified in is found, then the other section.

Multipath
"IPMultipathType" field MUST be set to appropriate multipath
information type TBD4 has following format:

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|IPMultipathType| IP Multipath Length | Reserved(MBZ) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ~
| (IP {2, 4, 8} and the "IP Multipath Information) |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|LbMultipathType| Information"
section MUST be included. In addition, the "Associated Label
Multipath Length | Reserved(MBZ) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ~
| (Label Information" section MUST be populated with a list of
labels corresponding to each IP address specified in the "IP
Multipath Information) |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Assoc Information" section. "Assoc Label Multipath Length | Reserved(MBZ) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ~
| (Associated Length"
MUST be set to a value representing the length in octets of the
"Associated Label Multipath Information) |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 2: Multipath Information Type TBD4 Information" field.

9.3. Label Based Load Balancer & Not Pushing ELI/EL

o IPMultipathType The responder MUST set {L=1, E=0} in DS flags.

o If multipath information type {2, 4, 8} is received, the responder
MUST reply with multipath type {0}.

o If multipath information type {9} is received, the responder MUST
comply with [RFC4379] and [RFC6424] as updated by Section 3.

o If multipath information type {TBD4} is received, the following
procedures are to be used:

* 0 when The responder MUST reply with multipath information type
{TBD4}.

* The "IP Multipath Information" and "Associated Label Multipath
Information" sections MUST be omitted (NULL).

* If no matching label is omitted. Otherwise one of
IP found, then the "LbMultipathType" field
MUST be set to multipath information values: {2, 4, 8}.

o IP type {0} and the "Label
Multipath Information

* This Information" section is MUST also be omitted when "IPMultipathType" (NULL).

* If at least one matching label is 0. Otherwise
this found, then the
"LbMultipathType" field MUST be set to the appropriate
multipath information type {9} and the "Label Multipath
Information" section reuses IP MUST be included.

9.4. Label Based Load Balancer & Pushes ELI/EL

o The responder MUST set {L=1, E=1} in DS flags.

o If multipath information from [RFC4379].
Specifically, type {2, 4, 8} is received, the responder
MUST reply with multipath type {0}.

o If multipath information for values {2, 4, 8} can type {9, TBD4} is received, the following procedures
are to be
used.

o LbMultipathType used:

* 0 when "Label The responder MUST respond with multipath type {TBD4}.

* The "IP Multipath Information" is section MUST be omitted. Otherwise
label multipath information value {9}.

o Label Multipath Information

* This section is omitted when "LbMultipathType" is 0. Otherwise
this section reuses The label set specified in the received label multipath
information from [RFC4379].
Specifically, multipath information for value {9} can MUST be used.

o Associated Label Multipath Information used to determine the returning Label/Label
pairs.

* "Assoc Label Multipath Length" is a 16 bit field of If received multipath information which indicates length in octets of type was {TBD4}, received
"Label Multipath Information" sections MUST NOT be used to
determine the associated label multipath information. portion of returning Label/Label
pairs.

* "Associated Label If no matching label is found, then the "LbMultipathType" field
MUST be set to multipath information type {0} and "Label
Multipath Information" is a list of labels
with each label described in 24 bits. This section MUST be
omitted in an MPLS echo request message. A midpoint which
pushes ELI/EL labels SHOULD include omitted. In addition,
"Assoc Label Multipath
Information" in its MPLS echo reply message, along with either
"IP Length" MUST be set to 0, and the
"Associated Label Multipath Information" or section MUST also be
omitted.

* If at least one matching label is found, then the
"LbMultipathType" field MUST be set to the appropriate
multipath information type {9} and the "Label Multipath Information".
Each specified associated label described in this
Information" section maps
to specific IP address OR label described in MUST be included. In addition, the "IP
"Associated Label Multipath Information" section or MUST be
populated with a list of labels corresponding to each label
specified in the "Label Multipath Information" section.
For example, if 3 IP addresses are specified "Assoc
Label Multipath Length" MUST be set to a value representing the
length in octets of the "IP "Associated Label Multipath
Information" section, then there MUST be 3 labels
described field.

9.5. Flow-Aware MS-PW Stitching LSR

A stitching LSR that cross-connects flow-aware Pseudowires behaves in
one of two ways:

o Load balances on the previous flow label, and carries over the
same flow label. For this section. First label maps to case, the lowest IP
address specified, second label maps stitching LSR is to behave as
described in Section 9.3.

o Load balances on the second lowest IP
address specified previous flow label, and third replaces the flow
label maps to with a newly computed label. For this case, the third lowest IP
address specified. stitching
LSR is to behave as described in Section 9.4.

10. Supported and Unsupported Cases

The MPLS architecture never defined does not define strict rules on how
implementations are to identify hash "keys" for load balancing
purpose. As a result, implementations may be of the following load
balancer types:

1. IP Based Load Balancer. IP-based load balancer.
2. Label Based Load Balancer. Label-based load balancer.
3. Label Label- and IP Based Load Balancer. IP-based load balancer.

For cases (2) and (3), an implementation can include different sets
of labels from the label stack for load balancing purpose. Thus the
following sub-cases are possible:

a. Entire label stack.
b. Top N labels from label stack where the number of labels in label
stack is >N.
c. Bottom N labels from label stack where the number of labels in
label stack is >N.

In a scenario where there is one Flow Label flow label or Entropy Label entropy label present
in the label stack, the following further cases are possible for
(2b), (2c), (3b) and (3c):

1. N labels from label stack include Flow Label flow label or Entropy Label. entropy label.
2. N labels from label stack does do not include Flow Label flow label or Entropy
Label. entropy
label.

Also in a scenario where there are multiple Entropy Labels entropy labels present in
the label stack, it is possible for implementations to employ
deviating techniques:

o Search for entropy stops at the first Entropy Label. entropy label.

o Search for entropy includes any Entropy Label entropy label found plus continues
to search for entropy in the label stack.

Furthermore, handling of reserved (i.e. (i.e., special) labels varies among
implementations:

o Reserved labels are used in the hash as any other label would be
(a bad
(not a recommended practice).
o Reserved labels are skipped over and, for implementations limited
to N labels, the reserved labels do not count towards the limit of
N.
o Reserved labels are skipped over and, for implementations limited
to N labels, the reserved labels count towards the limit of N.

It is important to point this out since the presence of GAL will
affect those implementations which include reserved labels for load
balancing purpose. purposes.

As can be seen from the above, there are many flavors types of potential load
balancing implementations. Attempting for any OAM tools to support
ECMP discovery and traversal over all flavors of such will types would require fairly
complex procedures and implementations to support those
complex procedures. Complexities in OAM tools will produce have minimal
benefits benefit
if the majority of implementations are expected to employ only a
small subset of the cases described above.

o Section 4.3 of [RFC6790] states that in implementations, for load
balancing purpose, purposes, parsing beyond the label stack after finding
Entropy Label is
an entropy label has "limited incremental value". Therefore, it
is expected that most implementations will be of types "IP Based Load
Balancer" "IP-based
load balancer" or "Label Based Load Balancer". "Label-based load balancer".

o Section 2.4.5.1 of [RFC7325] recommends that search searching for entropies
from entropy
labels in the label stack should terminate upon finding the first
Entropy Label.
entropy label. Therefore, it is expected that implementations
will only include the first (top-most) Entropy Label entropy label when there
are multiple Entropy Labels entropy labels in the label stack.

o It is expected that, in most cases, the number of labels in the
label stack will not exceed number of labels (N) which
implementations can include for load balancing purpose. purposes.

o It is expected that labels in the label stack, besides Flow Label the flow
label and Entropy Label, entropy label, are constant for the lifetime of a single
LSP multipath traceroute operation. Therefore, deviating load
balancing implementations with respect to reserved labels should
not affect this tool.

Thus [RFC4379], [RFC6424] [RFC6424], and this document will support supports cases (1) and
(2a1), where only the first (top-most) Entropy Label entropy label is included when
there are multiple Entropy Labels entropy labels in the label stack.

11. Security Considerations

This document extends the LSP Ping and Traceroute mechanism mechanisms to
discover and exercise ECMP paths when an LSP uses ELI/EL in the label
stack. Additional
processings are processing is required for responder and initiator
nodes.
Responder The responder node that pushes ELI/EL will need to compute
and return multipath data including associated EL. Initiator The initiator
node will need to store and handle both IP multipath and label
multipath information, and include destination IP addresses and/or
ELs in MPLS echo request
packet packets as well as in carried multipath information
sent to downstream nodes. Due to additional processing, it is critical that proper This document does not itself introduce
any new security considerations. The security measures described in [RFC4379]
[RFC4379], [RFC6424], and [RFC6424] [RFC6790] are followed. applicable. [RFC6424]
provides guidelines if a network operator wants to prevent tracing or
does not want to expose details of the tunnel and [RFC6790] provides
guidance on the use of the EL.

12. IANA Considerations

12.1. Entropy Label FEC

The IANA is requested to assign a new sub-TLV from the "Sub-TLVs for
TLV Types 1, 16, and 21" section from the "Multi-Protocol Label
Switching (MPLS) Label Switched Paths (LSPs) Ping Parameters - TLVs"
registry ([IANA-MPLS-LSP-PING]).

Sub-Type Sub-TLV Name Reference
-------- ------------ ---------
TBD1 Entropy label FEC this document

12.2. DS Flags

The IANA is requested to assign new bit numbers from the "DS flags"
sub-registry from the "Multi-Protocol Label Switching (MPLS) Label
Switched Paths (LSPs) Ping Parameters - TLVs" registry
([IANA-MPLS-LSP-PING]).

Note: the "DS flags" sub-registry is created by [RFC7537].

Bit number Name Reference
---------- ---------------------------------------- ---------
TBD2 E: ELI/EL push indicator this document
TBD3 L: Label based Label-based load balance indicator this document

12.2. Multpath

12.3. Multipath Type

The IANA is requested to assign a new value from the "Multipath Type"
sub-registry from the "Multi-Protocol Label Switching (MPLS) Label
Switched Paths (LSPs) Ping Parameters - TLVs" registry
([IANA-MPLS-LSP-PING]).

Note: the The "Multipath Type" sub-registry is created by [RFC7537].

Value Meaning Reference
---------- ---------------------------------------- ---------
TBD4 IP and label set this document

12.3. Entropy Label FEC

The IANA is requested to assign a new sub-TLV from the "Sub-TLVs for
TLV Types 1 and 16" section from the "Multi-Protocol Label Switching
(MPLS) Label Switched Paths (LSPs) Ping Parameters - TLVs" registry
([IANA-MPLS-LSP-PING]).

Sub-Type Sub-TLV Name Reference
-------- ------------ ---------
TBD1 Entropy Label FEC this document

13. Acknowledgements

Authors

The authors would like to thank Loa Andersson, Curtis Villamizar,
Daniel King, Sriganesh Kini and Kini, Victor Ji Ji, and Acee Lindem for
performing thorough review reviews and providing valuable comments.

14. Contributing Authors

Nagendra Kumar
Cisco Systems, Inc.
Email: naikumar@cisco.com

15. References

15.1. Normative References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.

[RFC4379] Kompella, K. and G. Swallow, "Detecting Multi-Protocol
Label Switched (MPLS) Data Plane Failures", RFC 4379,
DOI 10.17487/RFC4379, February 2006,
<http://www.rfc-editor.org/info/rfc4379>.

[RFC6424] Bahadur, N., Kompella, K., and G. Swallow, "Mechanism for
Performing Label Switched Path Ping (LSP Ping) over MPLS
Tunnels", RFC 6424, DOI 10.17487/RFC6424, November 2011,
<http://www.rfc-editor.org/info/rfc6424>.

[RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and
L. Yong, "The Use of Entropy Labels in MPLS Forwarding",
RFC 6790, DOI 10.17487/RFC6790, November 2012,
<http://www.rfc-editor.org/info/rfc6790>.

[RFC7537] Decraene, B., Akiya, N., Pignataro, C., Andersson, L., and
S. Aldrin, "IANA Registries for LSP Ping Code Points",
RFC 7537, DOI 10.17487/RFC7537, May 2015,
<http://www.rfc-editor.org/info/rfc7537>.

15.2. Informative References

[I-D.ravisingh-mpls-el-for-seamless-mpls]
Singh, R., Shen, Y., and J. Drake, "Entropy label for
seamless MPLS", draft-ravisingh-mpls-el-for-seamless-
mpls-04 (work in progress), October 2014.

[IANA-MPLS-LSP-PING]
IANA, "Multi-Protocol Label Switching (MPLS) Label
Switched Paths (LSPs) Ping Parameters",
<http://www.iana.org/assignments/mpls-lsp-ping-parameters/
mpls-lsp-ping-parameters.xhtml>.

[RFC6391] Bryant, S., Ed., Filsfils, C., Drafz, U., Kompella, V.,
Regan, J., and S. Amante, "Flow-Aware Transport of
Pseudowires over an MPLS Packet Switched Network",
RFC 6391, DOI 10.17487/RFC6391, November 2011,
<http://www.rfc-editor.org/info/rfc6391>.

[RFC7325] Villamizar, C., Ed., Kompella, K., Amante, S., Malis, A.,
and C. Pignataro, "MPLS Forwarding Compliance and
Performance Requirements", RFC 7325, DOI 10.17487/RFC7325,
August 2014, <http://www.rfc-editor.org/info/rfc7325>.

Authors' Addresses

Nobo Akiya
Big Switch Networks

Email: nobo.akiya.dev@gmail.com

George Swallow
Cisco Systems, Inc.

Email: swallow@cisco.com

Carlos Pignataro
Cisco Systems, Inc.

Email: cpignata@cisco.com

Andrew G. Malis
Huawei Technologies

Email: agmalis@gmail.com
Sam Aldrin
Google

Email: aldrin.ietf@gmail.com