draft-akiya-mpls-entropy-lsp-ping-01.txt   draft-akiya-mpls-entropy-lsp-ping-02.txt 
Internet Engineering Task Force N. Akiya Internet Engineering Task Force N. Akiya
Internet-Draft G. Swallow Internet-Draft G. Swallow
Updates: 4379,6790 (if approved) C. Pignataro Updates: 4379,6424,6790 (if approved) C. Pignataro
Intended status: Standards Track Cisco Systems Intended status: Standards Track Cisco Systems
Expires: June 18, 2014 December 15, 2013 Expires: January 5, 2015 A. Malis
S. Aldrin
Huawei Technologies
July 4, 2014
Label Switched Path (LSP) Ping/Trace over MPLS Network Label Switched Path (LSP) and Pseudowire (PW) Ping/Trace over
using Entropy Labels (EL) MPLS Network using Entropy Labels (EL)
draft-akiya-mpls-entropy-lsp-ping-01 draft-akiya-mpls-entropy-lsp-ping-02
Abstract Abstract
The Multiprotocol Label Switching (MPLS) Label Switched Path (LSP) The Multiprotocol Label Switching (MPLS) Label Switched Path (LSP)
Ping and Traceroute are used to exercise specific paths of Equal Cost Ping and Traceroute are used to exercise specific paths of Equal-Cost
Multipath (ECMP). When LSP is signaled to use Entropy Label (EL) Multipath (ECMP). When LSP is signaled to use Entropy Label (EL)
described in RFC6790, the ability for LSP Ping and Traceroute described in RFC6790, the ability for LSP Ping and Traceroute
operation to discover and exercise ECMP paths has been lost in operation to discover and exercise ECMP paths has been lost in
scenarios which LSRs apply deviating load balance techniques. One scenarios which LSRs apply deviating load balance techniques. One
such scenario is when some LSRs apply EL based load balancing while such scenario is when some LSRs apply EL based load balancing while
other LSRs apply non-EL based load balancing (ex: IP). Another other LSRs apply non-EL based load balancing (ex: IP). Another
scenario is when EL based LSP is stitched with another LSP which can scenario is when EL based LSP is stitched with another LSP which can
be EL based or non-EL based. be EL based or non-EL based.
This document extends the MPLS LSP Ping and Traceroute mechanisms to This document extends the MPLS LSP Ping and Traceroute mechanisms to
restore the ability of exercising specific paths of ECMP over LSP restore the ability of exercising specific paths of ECMP over LSP
which make use of Entropy Label. This document updates RFC4379 and which make use of Entropy Label. This document updates RFC4379,
RFC6790. RFC6424 and RFC6790.
Requirements Language Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
skipping to change at page 2, line 10 skipping to change at page 2, line 10
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on June 18, 2014. This Internet-Draft will expire on January 5, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
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the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
3. Multipath Type 9 . . . . . . . . . . . . . . . . . . . . . . 5 1.2. Prerequisite . . . . . . . . . . . . . . . . . . . . . . 4
4. Initiating LSR Procedures . . . . . . . . . . . . . . . . . . 6 1.3. Background . . . . . . . . . . . . . . . . . . . . . . . 4
5. Responder LSR Procedures . . . . . . . . . . . . . . . . . . 7 2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5.1. IP Based Load Balancer & Not Pushing ELI/EL . . . . . . . 8 3. Multipath Type 9 . . . . . . . . . . . . . . . . . . . . . . 7
5.2. IP Based Load Balancer & Pushes ELI/EL . . . . . . . . . 8 4. Pseudowire Tracing . . . . . . . . . . . . . . . . . . . . . 7
5.3. Label Based Load Balancer & Not Pushing ELI/EL . . . . . 9 5. Initiating LSR Procedures . . . . . . . . . . . . . . . . . . 8
5.4. Label Based Load Balancer & Pushes ELI/EL . . . . . . . . 9 6. Responder LSR Procedures . . . . . . . . . . . . . . . . . . 9
5.5. FAT MS-PW Stitching LSR . . . . . . . . . . . . . . . . . 10 6.1. IP Based Load Balancer & Not Pushing ELI/EL . . . . . . . 9
6. Entropy Label FEC . . . . . . . . . . . . . . . . . . . . . . 10 6.2. IP Based Load Balancer & Pushes ELI/EL . . . . . . . . . 10
7. DS Flags: L and E . . . . . . . . . . . . . . . . . . . . . . 11 6.3. Label Based Load Balancer & Not Pushing ELI/EL . . . . . 11
8. New Multipath Information Type: 10 . . . . . . . . . . . . . 12 6.4. Label Based Load Balancer & Pushes ELI/EL . . . . . . . . 11
9. Unsupported Cases . . . . . . . . . . . . . . . . . . . . . . 13 6.5. Flow Aware MS-PW Stitching LSR . . . . . . . . . . . . . 12
10. Security Considerations . . . . . . . . . . . . . . . . . . . 14 7. Entropy Label FEC . . . . . . . . . . . . . . . . . . . . . . 12
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 8. DS Flags: L and E . . . . . . . . . . . . . . . . . . . . . . 13
11.1. New Sub-Registries . . . . . . . . . . . . . . . . . . . 14 9. New Multipath Information Type: 10 . . . . . . . . . . . . . 14
11.1.1. DS Flags . . . . . . . . . . . . . . . . . . . . . . 14 10. Supported and Unsupported Cases . . . . . . . . . . . . . . . 16
11.1.2. Multipath Type . . . . . . . . . . . . . . . . . . . 15 11. Security Considerations . . . . . . . . . . . . . . . . . . . 18
11.2. Entropy Label FEC . . . . . . . . . . . . . . . . . . . 15 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15 12.1. New Sub-Registries . . . . . . . . . . . . . . . . . . . 18
13. Contributing Authors . . . . . . . . . . . . . . . . . . . . 15 12.1.1. DS Flags . . . . . . . . . . . . . . . . . . . . . . 18
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 16 12.1.2. Multipath Type . . . . . . . . . . . . . . . . . . . 19
14.1. Normative References . . . . . . . . . . . . . . . . . . 16 12.2. Entropy Label FEC . . . . . . . . . . . . . . . . . . . 19
14.2. Informative References . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 20
14. Contributing Authors . . . . . . . . . . . . . . . . . . . . 20
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 20
15.1. Normative References . . . . . . . . . . . . . . . . . . 20
15.2. Informative References . . . . . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21
1. Introduction 1. Introduction
1.1. Terminology
The following acronyms/terminologies 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 MPLS echo request.
o Responder LSR - LSR which receives MPLS echo request and sends
MPLS echo reply.
o IP Based Load Balancer - LSR which load balances on fields from IP
header (and possibly fields from upper layers), and does not
consider entropy label from label stack (i.e. Flow Label or
Entropy Label) for load balancing purpose.
o Label Based Load Balancer - LSR which load balances on entropy
label from label stack (i.e. Flow Label or Entropy Label), and
does not consider fields from IP header (and possibly fields from
upper layers) for load balancing purpose.
o Label and IP Based Load Balancer - LSR which load balances on both
labels from label stack (including Flow Label or Entropy Label if
present) and fields from IP header (and possibly fields from upper
layers).
1.2. Prerequisite
MPLS implementations employ wide variety of load balancing techniques
in terms of fields used for hash "keys". [RFC4379] and [RFC6424] are
designed to provide multipath support for subset of techniques.
Intent of this document is to restore multipath support for those
supported techniques which have been compromised by the introduction
of [RFC6790] (i.e. Entropy Labels). Section 10 describes supported
and unsupported cases, and it may be useful for one to visit this
section first.
1.3. Background
Section 3.3.1 of [RFC4379] specifies multipath information encoding Section 3.3.1 of [RFC4379] specifies multipath information encoding
which can be used by LSP Ping initiator to trace and validate all in Downstream Mapping TLV (Section 3.3 of [RFC4379]) and Downstream
ECMP paths between ingress and egress. These encodings are Detailed Mapping TLV (Section 3.3 of [RFC6424]) which can be used by
sufficient when all the LSRs along the path(s), between ingress and LSP Ping initiator to trace and validate all ECMP paths between
egress, consider same set of "keys" as input for load balancing ingress and egress. These encodings are sufficient when all the LSRs
algorithm: all IP based or all label based. along the path(s), between ingress and egress, consider same set of
"keys" as input for load balancing algorithm: all IP based or all
label based.
With introduction of [RFC6790], it is quite normal to see set of LSRs With introduction of [RFC6790], it is quite normal to see set of LSRs
performing load balancing based on EL/ELI while others still follow performing load balancing based on EL/ELI while others still follow
the traditional way (IP based). This results in LSP Ping initiator the traditional way (IP based). This results in LSP Ping initiator
not be able to trace and validate all ECMP paths in following not be able to trace and validate all ECMP paths in following
scenarios: scenarios:
o One or more transit LSRs along LSP with ELI/EL in label stack do o One or more transit LSRs along LSP with ELI/EL in label stack do
not perform ECMP load balancing based on EL (hashes based on not perform ECMP load balancing based on EL (hashes based on
"keys" including IP destination address). This scenario is not "keys" including IP destination address). This scenario is not
skipping to change at page 3, line 42 skipping to change at page 5, line 8
[I-D.ravisingh-mpls-el-for-seamless-mpls]. [I-D.ravisingh-mpls-el-for-seamless-mpls].
These scenarios will be quite common because every deployment of These scenarios will be quite common because every deployment of
[RFC6790] will invariably end up with nodes that support ELI/EL and [RFC6790] will invariably end up with nodes that support ELI/EL and
nodes that do not. There will typically be areas that support ELI/EL nodes that do not. There will typically be areas that support ELI/EL
and areas that do not. and areas that do not.
As pointed out in [RFC6790] the procedures of [RFC4379] with respect As pointed out in [RFC6790] the procedures of [RFC4379] with respect
to multipath information type {9} are incomplete. However [RFC6790] to multipath information type {9} are incomplete. However [RFC6790]
does not actually update [RFC4379]. Further the specific EL location does not actually update [RFC4379]. Further the specific EL location
is not clearly defined, particularly in the case of Flow-Aware is not clearly defined, particularly in the case of Flow Aware
Transport Pseudowires [RFC6391]. This document defines a new FEC Pseudowires [RFC6391]. This document defines a new FEC Stack sub-TLV
Stack sub-TLV for the Entropy Label. Section 3 of this document for the Entropy Label. Section 3 of this document updates the
updates the procedures for multipath information type {9} described procedures for multipath information type {9} described in [RFC4379].
in [RFC4379] Rest of this document describes extensions required to Rest of this document describes extensions required to restore ECMP
restore ECMP discovery and tracing capabilities for scenarios discovery and tracing capabilities for scenarios described.
described.
2. Overview 2. Overview
[RFC4379] describes LSP traceroute as an operation where the [RFC4379] describes LSP traceroute as an operation where the
initiating LSR send a series of MPLS echo requests towards the same initiating LSR send a series of MPLS echo requests towards the same
destination. The first packet in the series have the TTL set to 1. destination. The first packet in the series have the TTL set to 1.
When the echo reply is received from the LSR one hop away the second When the echo reply is received from the LSR one hop away the second
echo request in the series is sent with the TTL set to 2, for each echo request in the series is sent with the TTL set to 2, for each
echo request the TLL is incremented by one until a response is echo request the TLL is incremented by one until a response is
received from the intended destination. Initiating LSR discovers and received from the intended destination. Initiating LSR discovers and
exercises ECMP by obtaining multipath information from each transit exercises ECMP by obtaining multipath information from each transit
LSR and using specific destination IP address or specific entropy LSR and using specific destination IP address or specific entropy
label. label.
Notion of {x, y, z} from here on refers to Multipath information
types x, y or z.
LSP Ping initiating LSR sends MPLS echo request with multipath LSP Ping initiating LSR sends MPLS echo request with multipath
information. This multipath information is described in DSMAP/DDMAP information. This multipath information is described in DSMAP/DDMAP
TLV of echo request, and can contain set of IP addresses or set of TLV of echo request, and may contain set of IP addresses or set of
labels today. Multipath information types {2, 4, 8} carry set of IP labels. Multipath information types {2, 4, 8} carry set of IP
addresses and multipath information type {9} carries set of labels. addresses and multipath information type {9} carries set of labels.
Responder LSR (receiver of MPLS echo request) is to determine subset Responder LSR (receiver of MPLS echo request) will determine the
of initiator specified multipath information which load balances to subset of initiator specified multipath information which load
each downstream (outgoing interface). Responder LSR sends MPLS echo balances to each downstream (outgoing interface). Responder LSR
reply with resulting multipath information per downstream (outgoing sends MPLS echo reply with resulting multipath information per
interface) back to the initiating LSR. Initiating LSR is then able downstream (outgoing interface) back to the initiating LSR.
to use specific IP destination address or specific label to exercise Initiating LSR is then able to use specific IP destination address or
specific ECMP path on the responder LSR. specific label to exercise specific ECMP path on the responder LSR.
Current behavior is problematic in following scenarios: Current behavior is problematic in following scenarios:
o Initiating LSR sends IP multipath information, but responder LSR o Initiating LSR sends IP multipath information, but responder LSR
load balances on labels. load balances on labels.
o Initiating LSR sends label multipath information, but responder o Initiating LSR sends label multipath information, but responder
LSR load balances on IP addresses. LSR load balances on IP addresses.
o Initiating LSR sends one of existing multipath information to LSR o Initiating LSR sends existing multipath information to LSR which
which pushes ELI/EL in label stack, but initiating LSR can only pushes ELI/EL in label stack, but the initiating LSR can only
continue to discover and exercise specific path of ECMP if LSR continue to discover and exercise specific path of ECMP, if the
which pushes ELI/EL responds with both IP addresses and associated LSR which pushes ELI/EL responds with both IP addresses and
EL corresponding to each IP address. This is because: associated EL corresponding to each IP address. This is because:
* ELI/EL pushing LSR that is a stitching point will load balance * ELI/EL pushing LSR that is a stitching point will load balance
based on IP address. based on IP address.
* Downstream LSR(s) of ELI/EL pushing LSR may load balance based * Downstream LSR(s) of ELI/EL pushing LSR may load balance based
on ELs. on ELs.
o Initiating LSR sends one of existing multipath information to ELI/ o Initiating LSR sends one of existing multipath information to ELI/
EL pushing LSR, but initiating LSR can only continue to discover EL pushing LSR, but initiating LSR can only continue to discover
and exercise specific path of ECMP if ELI/EL pushing LSR responds and exercise specific path of ECMP if ELI/EL pushing LSR responds
skipping to change at page 5, line 21 skipping to change at page 6, line 33
* ELI/EL pushing LSR that is a stitching point will load balance * ELI/EL pushing LSR that is a stitching point will load balance
based on EL from previous LSP and pushes new EL. based on EL from previous LSP and pushes new EL.
* Downstream LSR(s) of ELI/EL pushing LSR may load balance based * Downstream LSR(s) of ELI/EL pushing LSR may load balance based
on new ELs. on new ELs.
The above scenarios point to how the existing multipath information The above scenarios point to how the existing multipath information
is insufficient when LSP traceroute is operated on an LSP with is insufficient when LSP traceroute is operated on an LSP with
Entropy Labels described by [RFC6790]. Therefore, this document Entropy Labels described by [RFC6790]. Therefore, this document
defines a multipath information type to be used in the DSMAP/DDMAP of defines a multipath information type to be used in the DSMAP/DDMAP of
MPLS echo request/reply packets in Section 8. MPLS echo request/reply packets in Section 9.
In addition, responder LSR can reply with empty multipath information In addition, responder LSR can reply with empty multipath information
if no IP address set or label set from received multipath information if no IP address set or label set from received multipath information
matched load balancing to a downstream. Empty return is also matched load balancing to a downstream. Empty return is also
possible if initiating LSR sends multipath information of one type, possible if initiating LSR sends multipath information of one type,
IP address or label, but responder LSR load balances on the other IP address or label, but responder LSR load balances on the other
type. To disambiguate between the two results, this document type. To disambiguate between the two results, this document
introduces new flags in the DSMAP/DDMAP TLV to allow responder LSR to introduces new flags in the DSMAP/DDMAP TLV to allow responder LSR to
describe the load balance technique being used. describe the load balance technique being used.
It is required that all LSRs along the LSP understand new flags as It is required that all LSRs along the LSP understand new flags as
well as new multipath information type. It is also required that well as new multipath information type. It is also required that
initiating LSR can select both IP destination address and label to initiating LSR can select both IP destination address and label to
use on transmitting MPLS echo request packets. Two additional DS use on transmitting MPLS echo request packets. Two additional DS
Flags are defined for the DSMAP and DDMAP TLVs in Section 7. Flags are defined for the DSMAP and DDMAP TLVs in Section 8. These
two flags are used by the responder LSR to describe its load balance
behavior on received MPLS echo request.
Note that the terms "IP Based Load Balancer", "Label Based Load
Balancer" and "Label Based Load Balancer" are in context of how
received MPLS echo request is handled by the responder LSR.
3. Multipath Type 9 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 [RFC4379] defined multipath type {9} for tracing of LSPs where label
based load-balancing is used. However, as pointed out in [RFC6790], based load-balancing is used. However, as pointed out in [RFC6790],
the procedures for using this type are incomplete. First, the the procedures for using this type are incomplete as the specific
specific location of the label was not defined. What was assumed, location of the label was not defined. It was assumed that the
but not spelled out, was that the presence of multipath type {9} presence of multipath type {9} implied the value of the bottom-of-
meant the responder should act as if the payload of the received stack label should be varied by the values indicated by multipath to
packet were non-IP and that the bottom-of-stack label should be determine their respective out-going interfaces.
replaced by the values indicated by multipath type {9} to determine
their respective out-going interfaces.
Further, with the introduction of [RFC6790], entropy labels may now Section 7 defines a new FEC-Stack sub-TLV to indicate an entropy
appear anywhere in a label stack. label. These labels may appear anywhere in a label stack.
This section defines to which labels multipath type {9} can apply. Multipath type {9} applies to the first label in the label-stack that
Additionally it defines procedures for tracing pseudowires and flow- corresponds to an EL-FEC. If no such label is found, it applies to
aware pseudowires. These procedures pertain to the use of multipath the label at the bottom of the label stack.
information type {9} as well as type {10}.
Section 6 defines a new FEC-Stack sub-TLV to indicate and entropy 4. Pseudowire Tracing
label. Multipath type {9} applies exclusively to this sub-TLV. Any
LSP Ping message containing a DD-MAP or DS-MAP with multipath type
{9} MUST include an EL_FEC at the bottom of the FEC-Stack.
When an MPLS echo request message is received containing a FEC-Stack This section defines procedures for tracing pseudowires. These
with an EL-FEC at the bottom of the FEC stack and is not preceded by procedures pertain to the use of multipath information type {9} as
an entropy label, the responder must behave (for load balancing well as type {10}. In all cases below, when a control word is in use
purposes) as if the first word of the message were a Pseudowire the N-flag in the DDMAP or DSMAP MUST be set. Note that when a
Control Word. control word is not in use the returned DDMAPs or DSMAPs may not be
accurate.
In order to trace a non-FAT pseudowire, instead of including the In order to trace a non Flow-Aware Pseudowire the initiator includes
appropriate PW-FEC in the FEC-Stack, an EL-FEC is included. Tracing an EL-FEC instead of the appropriate PW-FEC at the bottom of the FEC-
in this way will cause compliant routers to return the proper Stack. Tracing in this way will cause compliant routers to return
outgoing interface. Note that this procedure only traces to the end the proper outgoing interface. Note that this procedure only traces
of the MPLS LSP at transport layer (e.g. LDP and/or RSVP). To to the end of the MPLS LSP that is under test and will not verify the
actually verify the PW-FEC or in the case of a MS-PW, to determine PW FEC. To actually verify the PW-FEC or in the case of a MS-PW, to
the next pseudowire label value, the initiator MUST repeat that step determine the next pseudowire label value, the initiator MUST repeat
of the trace, (i.e., repeating the TTL value used) but with the FEC- that step of the trace, (i.e., repeating the TTL value used) but with
Stack modified to contain the appropriate PW-FEC. the FEC-Stack modified to contain the appropriate PW-FEC. Note that
these procedures are applicable to scenarios which an initiator is
able to vary the bottom label (i.e. pseudowire label). Possible
scenarios are tracing multiple non Flow-Aware Pseudowires on the same
endpoints or tracing a non Flow-Aware Pseudowire provisioned with
multiple pseudowire labels.
In order to trace a Flow-Aware Transport Pseudowire, the initiator In order to trace a Flow Aware Pseudowire, the initiator includes an
includes an EL-FEC at the bottom of the FEC-Stack and pushes the EL-FEC at the bottom of the FEC-Stack and pushes the appropriate PW-
appropriate PW-FEC onto the FEC-Stack. FEC onto the FEC-Stack.
4. Initiating LSR Procedures In order to trace through non-compliant routers the initiator forms
an MPLS echo request message and includes a DDMAP or DSMAP with
multipath type {9}. For a non Flow-Aware Pseudowire it includes the
appropriate PW-FEC in the FEC-Stack. For a Flow Aware Pseudowire,
the initiator includes a NIL-FEC at the bottom of the FEC-Stack and
pushes the appropriate PW-FEC onto the FEC-Stack.
5. Initiating LSR Procedures
In order to facilitate the flow of the following text we speak in In order to facilitate the flow of the following text we speak in
terms of a boolean called EL_LSP maintained by the initiating LSR. terms of a boolean called EL_LSP maintained by the initiating LSR.
This value controls the multipath information type to be used in This value controls the multipath information type to be used in
transmitted echo request packets. When the initiating LSR is transmitted echo request packets. When the initiating LSR is
transmitting an echo request packet with DSMAP/DDMAP with a non-zero transmitting an echo request packet with DSMAP/DDMAP with a non-zero
multipath information type, then EL_LSP boolean MUST be consulted to multipath information type, then EL_LSP boolean MUST be consulted to
determine the multipath information type to use. determine the multipath information type to use.
In addition to procedures described in [RFC4379] as updated by In addition to procedures described in [RFC4379] as updated by
Section 3 and [RFC6424], initiating LSR MUST operate with following Section 3 and [RFC6424], initiating LSR MUST operate with following
procedures. procedures.
o When initiating LSR is IP based load balancer (not pushing ELI/ o When the initiating LSR pushes ELI/EL, initialize EL_LSP=True.
EL), initialize EL_LSP=False. Else set EL_LSP=False.
o When initiating LSR pushes ELI/EL, initialize EL_LSP=True.
o When initiating LSR is transmitting non-zero multipath information o When the initiating LSR is transmitting non-zero multipath
type: information type:
* If (EL_LSP) initiating LSR MUST use multipath information type * If (EL_LSP), the initiating LSR MUST use multipath information
{10}. type {10} unless same responder LSR cannot handle type {10}.
* Else initiating LSR MUST use multipath information type {2, 4, * Else the initiating LSR MAY use multipath information type {2,
8, 9}. 4, 8, 9}.
o When initiating LSR is transmitting multipath information type o When the initiating LSR is transmitting multipath information type
{10}, both "IP Multipath Information" and "Label Multipath {10}, both "IP Multipath Information" and "Label Multipath
Information" MUST be included, and "IP Associated Label Multipath Information" MUST be included, and "IP Associated Label Multipath
Information" MUST be omitted (NULL). Information" MUST be omitted (NULL).
o When initiating LSR receives echo reply with {L=0, E=1} in DS o When the initiating LSR receives echo reply with {L=0, E=1} in DS
flags with valid contents, set EL_LSP=True. flags with valid contents, set EL_LSP=True.
In following conditions, initiating LSR may have lost the ability to In following conditions, the initiating LSR may have lost the ability
exercise specific ECMP paths. Initiating LSR MAY continue with "best to exercise specific ECMP paths. The initiating LSR MAY continue
effort". with "best effort".
o Received echo reply contains empty multipath information. o Received echo reply contains empty multipath information.
o Received echo reply contains {L=0, E=<any>} DS flags, but does not o Received echo reply contains {L=0, E=<any>} DS flags, but does not
contain IP multipath information. contain IP multipath information.
o Received echo reply contains {L=1, E=<any>} DS flags, but does not o Received echo reply contains {L=1, E=<any>} DS flags, but does not
contain label multipath information. contain label multipath information.
o Received echo reply contains {L=<any>, E=1} DS flags, but does not o Received echo reply contains {L=<any>, E=1} DS flags, but does not
contain associated label multipath information. contain associated label multipath information.
o IP multipath information types {2, 4, 8} sent, and received echo o IP multipath information types {2, 4, 8} sent, and received echo
reply with {L=1, E=0} in DS flags. reply with {L=1, E=0} in DS flags.
o Multipath information type {10} sent, and received echo reply with o Multipath information type {10} sent, and received echo reply with
multipath information type other than {10}. multipath information type other than {10}.
5. Responder LSR Procedures 6. Responder LSR Procedures
Common Procedures: Responder LSR receiving MPLS echo request packet Common Procedures: The responder LSR receiving an MPLS echo request
with multipath information type {10} MUST validate following packet with multipath information type {10} MUST validate following
contents. Any deviation MUST result in responder LSR to consider the contents. Any deviation MUST result in the responder LSR to consider
packet as malformed and return code 1 (Malformed echo request the packet as malformed and return code 1 (Malformed echo request
received) in MPLS echo reply packet. received) in the MPLS echo reply packet.
o IP multipath information MUST be included. o IP multipath information MUST be included.
o Label multipath information MUST be included. o Label multipath information MUST be included.
o IP associated label multipath information MUST be omitted (NULL). o IP associated label multipath information MUST be omitted (NULL).
Following subsections describe expected responder LSR procedures when Following subsections describe expected responder LSR procedures when
echo reply is to include DSMAP/DDMAP TLVs, based on local load echo reply is to include DSMAP/DDMAP TLVs, based on local load
balance technique being employed. In case responder LSR performs balance technique being employed. In case the responder LSR performs
deviating load balance techniques per downstream basis, appropriate deviating load balance techniques per downstream basis, appropriate
procedures matching to each downstream load balance technique MUST be procedures matching to each downstream load balance technique MUST be
operated. operated.
5.1. IP Based Load Balancer & Not Pushing ELI/EL 6.1. IP Based Load Balancer & Not Pushing ELI/EL
o Responder MUST set {L=0, E=0} in DS flags. o The responder MUST set {L=0, E=0} in DS flags.
o If multipath information type {2, 4, 8} is received, responder o If multipath information type {2, 4, 8} is received, the responder
MUST comply with [RFC4379]/[RFC6424]. MUST comply with [RFC4379] and [RFC6424].
o If multipath information type {9} is received, responder MUST o If multipath information type {9} is received, the responder MUST
reply with multipath type {0}. reply with multipath type {0}.
o If multipath information type {10} is received, responder MUST o If multipath information type {10} is received, following
reply with multipath information type {10}. "Label Multipath procedures are to be used:
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.
5.2. IP Based Load Balancer & Pushes ELI/EL * The responder MUST reply with multipath information type {10}.
o Responder MUST set {L=0, E=1} in DS flags. * "Label Multipath Information" and "Associated Label Multipath
Information" sections MUST be omitted (NULL).
o If multipath information type {9} is received, responder MUST * 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}. reply with multipath type {0}.
o If multipath type {2, 4, 8, 10} is received, responder MUST o If multipath type {2, 4, 8, 10} is received, following procedures
respond with multipath type {10}. See Section 8 for details of are to be used:
multipath type {10}. "Label Multipath Information" section MUST be
omitted (i.e. is it not there). IP address set specified in
received IP multipath information MUST be used to determine the
returning IP/Label pairs. If received multipath information type
was {10}, received "Label 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 Multipath Information" section MUST be omitted. In
addition, "Assoc Label Multipath Length" MUST be set to 0, and
"Associated Label Multipath Information" section MUST also be
omitted. 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. In addition, "Associated Label Multipath
Information" section MUST be populated with list of labels
corresponding to each IP address specified in "IP Multipath
Information" section. "Assoc Label Multipath Length" MUST be set
to a value representing length in octets of "Associated Label
Multipath Information" field.
5.3. Label Based Load Balancer & Not Pushing ELI/EL * The responder MUST respond with multipath type {10}. See
Section 9 for details of multipath type {10}.
o Responder MUST set {L=1, E=0} in DS flags. * "Label Multipath Information" section MUST be omitted (i.e. is
it not there).
o If multipath information type {2, 4, 8} is received, responder * IP address set specified in received IP multipath information
MUST be used to determine the returning IP/Label pairs.
* If received multipath information type was {10}, received
"Label 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
Multipath Information" section MUST be omitted. In addition,
"Assoc Label Multipath Length" MUST be set to 0, and
"Associated Label Multipath Information" section MUST also be
omitted.
* 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. In addition, "Associated Label
Multipath Information" section MUST be populated with list of
labels corresponding to each IP address specified in "IP
Multipath Information" section. "Assoc Label Multipath Length"
MUST be set to a value representing length in octets of
"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 with multipath type {0}. MUST reply with multipath type {0}.
o If multipath information type {9} is received, responder MUST o If multipath information type {9} is received, the responder MUST
comply with [RFC4379] /[RFC6424] as updated by Section 3. comply with [RFC4379] and [RFC6424] as updated by Section 3.
o If multipath information type {10} is received, responder MUST o If multipath information type {10} is received, following
reply with multipath information type {10}. "IP Multipath procedures are to be used:
Information" and "Associated Label Multipath Information" sections
MUST be omitted (NULL). If no matching label is found, then
"LbMultipathType" field MUST be set to multipath information type
{0} and "Label Multipath Information" section MUST also be omitted
(NULL). If at least one matching label is found, then
"LbMultipathType" field MUST be set to appropriate multipath
information type {9} and "Label Multipath Information" section
MUST be included.
5.4. Label Based Load Balancer & Pushes ELI/EL * The responder MUST reply with multipath information type {10}.
o Responder MUST set {L=1, E=1} in DS flags. * "IP Multipath Information" and "Associated Label Multipath
Information" sections MUST be omitted (NULL).
o If multipath information type {2, 4, 8} is received, responder * If no matching label is found, then "LbMultipathType" field
MUST be set to multipath information type {0} and "Label
Multipath Information" section MUST also be omitted (NULL).
* If at least one matching label is found, then "LbMultipathType"
field MUST be set to appropriate multipath information type {9}
and "Label Multipath Information" section MUST be included.
6.4. Label Based Load Balancer & Pushes ELI/EL
o The responder MUST set {L=1, E=1} in DS flags.
o If multipath information type {2, 4, 8} is received, the responder
MUST reply with multipath type {0}. MUST reply with multipath type {0}.
o If multipath type {9, 10} is received, responder MUST respond with o If multipath type {9, 10} is received, following procedures are to
multipath type {10}. "IP Multipath Information" section MUST be be used:
omitted. Label set specified in received label multipath
information MUST be used to determine the returning Label/Label
pairs. If received multipath information type was {10}, received
"Label Multipath Information" sections MUST NOT be used to
determine the associated label portion of returning Label/Label
pairs. If no matching label is found, then "LbMultipathType"
field MUST be set to multipath information type {0} and "Label
Multipath Information" section MUST be omitted. In addition,
"Assoc Label Multipath Length" MUST be set to 0, and "Associated
Label Multipath Information" section MUST also be omitted. If at
least one matching label is found, then "LbMultipathType" field
MUST be set to appropriate multipath information type {9} and
"Label Multipath Information" section MUST be included. In
addition, "Associated Label Multipath Information" section MUST be
populated 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.
5.5. FAT MS-PW Stitching LSR * The responder MUST respond with multipath type {10}.
Stitching LSR that xconnects Flow-Aware Transport Pseudowires behave * "IP Multipath Information" section MUST be omitted.
in one of two ways:
o Load balances on previous flow label, and carries over same flow * Label set specified in received label multipath information
label. For this case, stitching LSR is to behave as procedures MUST be used to determine the returning Label/Label pairs.
described in Section 5.3.
o Load balances on previous flow label, and replaces flow label with * If received multipath information type was {10}, received
"Label Multipath Information" sections MUST NOT be used to
determine the associated label portion of returning Label/Label
pairs.
* If no matching label is found, then "LbMultipathType" field
MUST be set to multipath information type {0} and "Label
Multipath Information" section MUST be omitted. In addition,
"Assoc Label Multipath Length" MUST be set to 0, and
"Associated Label Multipath Information" section MUST also be
omitted.
* If at least one matching label is found, then "LbMultipathType"
field MUST be set to appropriate multipath information type {9}
and "Label Multipath Information" section MUST be included. In
addition, "Associated Label Multipath Information" section MUST
be populated 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 in
one of two ways:
o Load balances on previous Flow Label, and carries over same Flow
Label. For this case, stitching LSR is to behave as procedures
described in Section 6.3.
o Load balances on previous Flow Label, and replaces Flow Label with
newly computed. For this case, stitching LSR is to behave as newly computed. For this case, stitching LSR is to behave as
procedures described in Section 5.4. procedures described in Section 6.4.
6. Entropy Label FEC 7. Entropy Label FEC
Entropy Label Indicator (ELI) is a reserved label that has no Entropy Label Indicator (ELI) is a reserved label that has no
explicit FEC associated, and has label value 7 assigned from the explicit FEC associated, and has label value 7 assigned from the
reserved range. Use Nil FEC as Target FEC Stack sub-TLV to account reserved range. Use Nil FEC as Target FEC Stack sub-TLV to account
for ELI in a Target FEC Stack TLV. for ELI in a Target FEC Stack TLV.
Entropy Label (EL) is a special purpose label with label value being Entropy Label (EL) is a special purpose label with label value being
discretionary (i.e. label value may not be from the reserved range). discretionary (i.e. label value may not be from the reserved range).
For LSP verification mechanics to perform its purpose, it is For LSP verification mechanics to perform its purpose, it is
necessary for a Target FEC Stack sub-TLV to clearly describe EL, necessary for a Target FEC Stack sub-TLV to clearly describe EL,
particularly in the scenario where label stack does not carry ELI particularly in the scenario where label stack does not carry ELI
(ex: FAT-PW [RFC6391]). Therefore, this document defines a EL FEC to (ex: Flow Aware Pseudowire [RFC6391]). Therefore, this document
allow a Target FEC Stack sub-TLV to be added to the Target FEC Stack defines a EL FEC to allow a Target FEC Stack sub-TLV to be added to
to account for EL. the Target FEC Stack to account for EL.
The Length is 4. Labels are 20-bit values treated as numbers. The Length is 4. Labels are 20-bit values treated as numbers.
0 1 2 3 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 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 | | Label | MBZ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Entropy Label FEC
Label is the actual label value inserted in the label stack; the MBZ Label is the actual label value inserted in the label stack; the MBZ
fields MUST be zero when sent and ignored on receipt. fields MUST be zero when sent and ignored on receipt.
7. DS Flags: L and E 8. DS Flags: L and E
Two flags, L and E, are added in DS Flags field of the DSMAP/DDMAP Two flags, L and E, are added in DS Flags field of the DSMAP/DDMAP
TLVs. Both flags MUST NOT be set in echo request packets when TLVs. Both flags MUST NOT be set in echo request packets when
sending, and ignored when received. Zero, one or both new flags MUST sending, and ignored when received. Zero, one or both new flags MUST
be set in echo reply packets. be set in echo reply packets.
DS Flags DS Flags
-------- --------
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
skipping to change at page 12, line 7 skipping to change at page 14, line 32
o {L=0, E=0} LSR load balances based on IP and does not push ELI/EL. o {L=0, E=0} LSR load balances based on IP and does not push ELI/EL.
o {L=0, E=1} LSR load balances based on IP and pushes ELI/EL. o {L=0, E=1} LSR load balances based on IP and pushes ELI/EL.
o {L=1, E=0} LSR load balances based on label and does not push ELI/ o {L=1, E=0} LSR load balances based on label and does not push ELI/
EL. EL.
o {L=1, E=1} LSR load balances based on label and pushes ELI/EL. o {L=1, E=1} LSR load balances based on label and pushes ELI/EL.
8. New Multipath Information Type: 10 9. New Multipath Information Type: 10
One new multipath information type is added to be used in DSMAP/DDMAP One new multipath information type is added to be used in DSMAP/DDMAP
TLVs. New multipath type has value of 10. TLVs. New multipath type has value of 10.
Key Type Multipath Information Key Type Multipath Information
--- ---------------- --------------------- --- ---------------- ---------------------
10 IP and label set IP addresses and label prefixes 10 IP and label set IP addresses and label prefixes
Multipath type 10 is comprised of three sections. One section to Multipath type 10 is comprised of three sections. One section to
describe IP address set. One section to describe label set. One describe IP address set. One section to describe label set. One
skipping to change at page 12, line 45 skipping to change at page 15, line 27
| (Label Multipath Information) | | (Label Multipath Information) |
~ ~ ~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved(MBZ) | Assoc Label Multipath Length | | Reserved(MBZ) | Assoc Label Multipath Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ~ ~ ~
| (Associated Label Multipath Information) | | (Associated Label Multipath Information) |
~ ~ ~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Multipath Information Type 10
o IPMultipathType o IPMultipathType
* 0 when "IP Multipath Information" is omitted. Otherwise one of * 0 when "IP Multipath Information" is omitted. Otherwise one of
IP multipath information values: {2, 4, 8}. IP multipath information values: {2, 4, 8}.
o IP Multipath Information o IP Multipath Information
* This section is omitted when "IPMultipathType" is 0. Otherwise * This section is omitted when "IPMultipathType" is 0. Otherwise
this section reuses IP multipath information from [RFC4379]. this section reuses IP multipath information from [RFC4379].
Specifically, multipath information for values {2, 4, 8} can be Specifically, multipath information for values {2, 4, 8} can be
used. used.
o LbMultipathType o LbMultipathType
* 0 when "Label Multipath Information" is omitted. Otherwise * 0 when "Label Multipath Information" is omitted. Otherwise
label multipath information value {9}. label multipath information value {9}.
skipping to change at page 13, line 42 skipping to change at page 16, line 24
Each specified associated label described in this section maps Each specified associated label described in this section maps
to specific IP address OR label described in the "IP Multipath to specific IP address OR label described in the "IP Multipath
Information" section or "Label Multipath Information" section. Information" section or "Label Multipath Information" section.
For example, if 3 IP addresses are specified in the "IP For example, if 3 IP addresses are specified in the "IP
Multipath Information" section, then there MUST be 3 labels Multipath Information" section, then there MUST be 3 labels
described in this section. First label maps to the lowest IP described in this section. First label maps to the lowest IP
address specified, second label maps to the second lowest IP address specified, second label maps to the second lowest IP
address specified and third label maps to the third lowest IP address specified and third label maps to the third lowest IP
address specified. address specified.
9. Unsupported Cases 10. Supported and Unsupported Cases
There are couple of scenarios where LSP path tracing mechanics are MPLS architecture never defined strict rules on how implementations
not supported in this draft revision. are to identify hash "keys" for load balancing purpose. As result,
implementations may be of following load balancer types:
o When one or more LSP transit node(s) performs label based load 1. IP Based Load Balancer.
balancing on a label that is not bottom-of-stack label when 2. Label Based Load Balancer.
Entropy Label Indicator is not included. 3. Label and IP Based Load Balancer.
o When one or more LSP transit node(s) performs label based load For cases (2) and (3), implementation can include different sets of
balancing on a label other than Entropy Label when Entropy Label labels from the label stack for load balancing purpose. Thus
Indicator and Entropy Label pair is included. following sub-cases are possible:
10. Security Considerations a. Entire label stack.
b. Top N labels from label stack where number of labels in label
stack is >N.
c. Bottom N labels from label stack where number of labels in label
stack is >N.
In a scenario where there is one Flow Label or Entropy Label present
in the label stack, following further cases are possible for (2b),
(2c), (3b) and (3c):
1. N labels from label stack include Flow Label or Entropy Label.
2. N labels from label stack does not include Flow Label or Entropy
Label.
Also in a scenario where there are multiple 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.
o Search for entropy includes any Entropy Label found plus continues
to search for entropy in the label stack.
Furthermore, handling of reserved (i.e. special) labels varies among
implementations:
o Reserved labels are used in the hash as any other label would be
(a bad 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 presence of GAL will affect
those implementations which include reserved labels for load
balancing purpose.
As can be seen from above, there are many flavors of potential load
balancing implementations. Attempting for any OAM tools to support
ECMP discovery and traversal over all flavors of such will require
fairly complex procedures and implementations to support those
complex procedures. Complexities in OAM tools will produce minimal
benefits if majority of implementations are expected to employ small
subset of cases described above.
o Section 4.3 of [RFC6790] states that implementations, for load
balancing purpose, parsing beyond the label stack after finding
Entropy Label is "limited incremental value". Therefore, it is
expected that most implementations will be of types "IP Based Load
Balancer" or "Label Based Load Balancer".
o Section 2.4.5.1 of [I-D.ietf-mpls-forwarding] recommends that
search for entropies from the label stack should terminate upon
finding the first Entropy Label. Therefore, it is expected that
implementations will only include the first (top-most) Entropy
Label when there are multiple Entropy Labels in the label stack.
o It is expected that, in most cases, number of labels in the label
stack will not exceed number of labels (N) which implementations
can include for load balancing purpose.
o It is expected that labels in the label stack, besides Flow Label
and 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] and this document will support cases (1)
and (2a1), where only the first (top-most) Entropy Label is included
when there are multiple Entropy Labels in the label stack.
11. Security Considerations
This document extends LSP Traceroute mechanism to discover and This document extends LSP Traceroute mechanism to discover and
exercise ECMP paths when LSP uses ELI/EL in label stack. Additional exercise ECMP paths when LSP uses ELI/EL in label stack. Additional
processings are required for responder and initiator nodes. processings are required for responder and initiator nodes.
Responder node that pushes ELI/EL will need to compute and return Responder node that pushes ELI/EL will need to compute and return
multipath data including associated EL. Initiator node will need to multipath data including associated EL. Initiator node will need to
store and handle both IP multipath and label multipath information, store and handle both IP multipath and label multipath information,
and include destination IP addresses and/or ELs in MPLS echo request and include destination IP addresses and/or ELs in MPLS echo request
packet as well as in carried multipath information to downstream packet as well as in carried multipath information to downstream
nodes. Due to additional processing, it is critical that proper nodes. Due to additional processing, it is critical that proper
security measures described in [RFC4379] and [RFC6424] are followed. security measures described in [RFC4379] and [RFC6424] are followed.
11. IANA Considerations 12. IANA Considerations
11.1. New Sub-Registries 12.1. New Sub-Registries
[RFC4379] defines the Downstream Mapping TLV, which has the Type 2 [RFC4379] defines the Downstream Mapping TLV, which has the Type 2
assigned from the "Multi-Protocol Label Switching (MPLS) Label assigned from the "Multi-Protocol Label Switching (MPLS) Label
Switched Paths (LSPs) Ping Parameters - TLVs" registry. [RFC6424] Switched Paths (LSPs) Ping Parameters - TLVs" registry. [RFC6424]
defines the Downstream Detailed Mapping TLV, which has the Type 20 defines the Downstream Detailed Mapping TLV, which has the Type 20
assigned from the "Multi-Protocol Label Switching (MPLS) Label assigned from the "Multi-Protocol Label Switching (MPLS) Label
Switched Paths (LSPs) Ping Parameters - TLVs" registry. Both TLVs Switched Paths (LSPs) Ping Parameters - TLVs" registry. Both TLVs
shares two fields: "DS Flags" and "Multipath Type". This document shares two fields: "DS Flags" and "Multipath Type". This document
requires allocation of new values in both the "DS Flags" and requires allocation of new values in both the "DS Flags" and
"Multipath Type" fields, which are not maintained by IANA today. "Multipath Type" fields, which are not maintained by IANA today.
Therefore, this document requests IANA to create new registries Therefore, this document requests IANA to create new registries
within [IANA-MPLS-LSP-PING] protocol to maintain "DS Flags" and within [IANA-MPLS-LSP-PING] protocol to maintain "DS Flags" and
"Multipath Type" fields. Name of registries and initial values are "Multipath Type" fields. Name of registries and initial values are
described in immediate sub-sections to follow. described in immediate sub-sections to follow.
11.1.1. DS Flags 12.1.1. DS Flags
Bit number Name Reference Bit number Name Reference
---------- ---------------------------------------- --------- ---------- ---------------------------------------- ---------
7 N: Treat as a Non-IP Packet RFC4379 7 N: Treat as a Non-IP Packet RFC4379
6 I: Interface and Label Stack Object Request RFC4379 6 I: Interface and Label Stack Object Request RFC4379
5 E: ELI/EL push indicator this document 5 E: ELI/EL push indicator this document
4 L: Label based load balance indicator this document 4 L: Label based load balance indicator this document
3-0 Unassigned 3-0 Unassigned
Assignments of DS Flags are via Standards Action [RFC5226] or IESG Assignments of DS Flags are via Standards Action [RFC5226] or IESG
Approval [RFC5226]. Approval [RFC5226].
Note that "DS Flags" is a field included in two TLVs defined in Note that "DS Flags" is a field included in two TLVs defined in
"Multi-Protocol Label Switching (MPLS) Label Switched Paths (LSPs) "Multi-Protocol Label Switching (MPLS) Label Switched Paths (LSPs)
Ping Parameters - TLVs" registry: Downstream Mapping TLV (value 2) Ping Parameters - TLVs" registry: Downstream Mapping TLV (value 2)
and Downstream Detailed Mapping TLV (value 20). Modification to "DS and Downstream Detailed Mapping TLV (value 20). Modification to "DS
Flags" registry will affect both TLVs. Flags" registry will affect both TLVs.
11.1.2. Multipath Type 12.1.2. Multipath Type
Value Meaning Reference Value Meaning Reference
---------- ---------------------------------------- --------- ---------- ---------------------------------------- ---------
0 no multipath RFC4379 0 no multipath RFC4379
1 Unassigned 1 Unassigned
2 IP address RFC4379 2 IP address RFC4379
3 Unassigned 3 Unassigned
4 IP address range RFC4379 4 IP address range RFC4379
5-7 Unassigned 5-7 Unassigned
8 Bit-masked IP address set RFC4379 8 Bit-masked IP address set RFC4379
skipping to change at page 15, line 35 skipping to change at page 19, line 45
Assignments of Multipath Type are via IETF Review [RFC5226] or IESG Assignments of Multipath Type are via IETF Review [RFC5226] or IESG
Approval [RFC5226]. Approval [RFC5226].
Note that "Multipath Type" is a field included in two TLVs defined in Note that "Multipath Type" is a field included in two TLVs defined in
"Multi-Protocol Label Switching (MPLS) Label Switched Paths (LSPs) "Multi-Protocol Label Switching (MPLS) Label Switched Paths (LSPs)
Ping Parameters - TLVs" registry: Downstream Mapping TLV (value 2) Ping Parameters - TLVs" registry: Downstream Mapping TLV (value 2)
and Downstream Detailed Mapping TLV (value 20). Modification to and Downstream Detailed Mapping TLV (value 20). Modification to
"Multipath Type" registry will affect both TLVs. "Multipath Type" registry will affect both TLVs.
11.2. Entropy Label FEC 12.2. Entropy Label FEC
IANA is requested to assign a new sub-TLV from the "Sub-TLVs for TLV IANA is requested to assign a new sub-TLV from the "Sub-TLVs for TLV
Types 1 and 16" section from "Multi-Protocol Label Switching (MPLS) Types 1 and 16" section from "Multi-Protocol Label Switching (MPLS)
Label Switched Paths (LSPs) Ping Parameters - TLVs" registry. Label Switched Paths (LSPs) Ping Parameters - TLVs" registry.
Sub-Type Sub-TLV Name Reference Sub-Type Sub-TLV Name Reference
-------- ------------ --------- -------- ------------ ---------
TBD1 Entropy Label FEC this document TBD1 Entropy Label FEC this document
12. Acknowledgements 13. Acknowledgements
Authors would like to thank Loa Andersson for performing thorough Authors would like to thank Loa Andersson, Curtis Villamizar, Daniel
review and providing valuable comments. King and Sriganesh Kini for performing thorough review and providing
valuable comments.
13. Contributing Authors 14. Contributing Authors
Nagendra Kumar Nagendra Kumar
Cisco Systems Cisco Systems
Email: naikumar@cisco.com Email: naikumar@cisco.com
14. References 15. References
14.1. Normative References 15.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4379] Kompella, K. and G. Swallow, "Detecting Multi-Protocol [RFC4379] Kompella, K. and G. Swallow, "Detecting Multi-Protocol
Label Switched (MPLS) Data Plane Failures", RFC 4379, Label Switched (MPLS) Data Plane Failures", RFC 4379,
February 2006. February 2006.
[RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and [RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and
L. Yong, "The Use of Entropy Labels in MPLS Forwarding", L. Yong, "The Use of Entropy Labels in MPLS Forwarding",
RFC 6790, November 2012. RFC 6790, November 2012.
14.2. Informative References 15.2. Informative References
[I-D.ietf-mpls-forwarding]
Villamizar, C., Kompella, K., Amante, S., Malis, A., and
C. Pignataro, "MPLS Forwarding Compliance and Performance
Requirements", draft-ietf-mpls-forwarding-09 (work in
progress), March 2014.
[I-D.ravisingh-mpls-el-for-seamless-mpls] [I-D.ravisingh-mpls-el-for-seamless-mpls]
Singh, R., Shen, Y., and J. Drake, "Entropy label for Singh, R., Shen, Y., and J. Drake, "Entropy label for
seamless MPLS", draft-ravisingh-mpls-el-for-seamless- seamless MPLS", draft-ravisingh-mpls-el-for-seamless-
mpls-01 (work in progress), October 2013. mpls-01 (work in progress), October 2013.
[IANA-MPLS-LSP-PING] [IANA-MPLS-LSP-PING]
IANA, "Multi-Protocol Label Switching (MPLS) Label IANA, "Multi-Protocol Label Switching (MPLS) Label
Switched Paths (LSPs) Ping Parameters", Switched Paths (LSPs) Ping Parameters",
<http://www.iana.org/assignments/mpls-lsp-ping-parameters/ <http://www.iana.org/assignments/mpls-lsp-ping-parameters/
skipping to change at line 770 skipping to change at page 21, line 40
George Swallow George Swallow
Cisco Systems Cisco Systems
Email: swallow@cisco.com Email: swallow@cisco.com
Carlos Pignataro Carlos Pignataro
Cisco Systems Cisco Systems
Email: cpignata@cisco.com Email: cpignata@cisco.com
Andrew G. Malis
Huawei Technologies
Email: agmalis@gmail.com
Sam Aldrin
Huawei Technologies
Email: aldrin.ietf@gmail.com
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