draft-akiya-mpls-entropy-lsp-ping-00.txt   draft-akiya-mpls-entropy-lsp-ping-01.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: 4379,6790 (if approved) C. Pignataro
Intended status: Standards Track Cisco Systems Intended status: Standards Track Cisco Systems
Expires: April 24, 2014 October 21, 2013 Expires: June 18, 2014 December 15, 2013
Label Switched Path (LSP) Ping/Trace over MPLS Network Label Switched Path (LSP) Ping/Trace over MPLS Network
using Entropy Labels (EL) using Entropy Labels (EL)
draft-akiya-mpls-entropy-lsp-ping-00 draft-akiya-mpls-entropy-lsp-ping-01
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). This ability has been lost on some scenarios which Multipath (ECMP). When LSP is signaled to use Entropy Label (EL)
makes use of [RFC6790]: Entropy Labels (EL). described in RFC6790, the ability for LSP Ping and Traceroute
operation to discover and exercise ECMP paths has been lost in
scenarios which LSRs apply deviating load balance techniques. One
such scenario is when some LSRs apply EL based load balancing while
other LSRs apply non-EL based load balancing (ex: IP). Another
scenario is when EL based LSP is stitched with another LSP which can
be EL based or non-EL based.
This document extends the MPLS LSP Ping and Traceroute 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 and
[RFC6790]. 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
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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 April 24, 2014. This Internet-Draft will expire on June 18, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2013 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
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
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
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
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(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
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
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
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 . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Multipath Type 9 . . . . . . . . . . . . . . . . . . . . . . 5 3. Multipath Type 9 . . . . . . . . . . . . . . . . . . . . . . 5
4. Initiating LSR Procedures . . . . . . . . . . . . . . . . . . 6 4. Initiating LSR Procedures . . . . . . . . . . . . . . . . . . 6
5. Responder LSR Procedures . . . . . . . . . . . . . . . . . . 7 5. Responder LSR Procedures . . . . . . . . . . . . . . . . . . 7
5.1. IP Based Load Balancer & Not Imposing ELI/EL . . . . . . 7 5.1. IP Based Load Balancer & Not Pushing ELI/EL . . . . . . . 8
5.2. IP Based Load Balancer & Imposing ELI/EL . . . . . . . . 8 5.2. IP Based Load Balancer & Pushes ELI/EL . . . . . . . . . 8
5.3. Label Based Load Balancer & Not Imposing ELI/EL . . . . . 8 5.3. Label Based Load Balancer & Not Pushing ELI/EL . . . . . 9
5.4. Label Based Load Balancer & Imposing ELI/EL . . . . . . . 9 5.4. Label Based Load Balancer & Pushes ELI/EL . . . . . . . . 9
5.5. FAT MS-PW Stitching LSR . . . . . . . . . . . . . . . . . 9 5.5. FAT MS-PW Stitching LSR . . . . . . . . . . . . . . . . . 10
6. Entropy Label FEC . . . . . . . . . . . . . . . . . . . . . . 10 6. Entropy Label FEC . . . . . . . . . . . . . . . . . . . . . . 10
7. DS Flags: L and E . . . . . . . . . . . . . . . . . . . . . . 10 7. DS Flags: L and E . . . . . . . . . . . . . . . . . . . . . . 11
8. New Multipath Information Type: 10 . . . . . . . . . . . . . 11 8. New Multipath Information Type: 10 . . . . . . . . . . . . . 12
9. Unsupported Cases . . . . . . . . . . . . . . . . . . . . . . 13 9. Unsupported Cases . . . . . . . . . . . . . . . . . . . . . . 13
10. Security Considerations . . . . . . . . . . . . . . . . . . . 13 10. Security Considerations . . . . . . . . . . . . . . . . . . . 14
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
11.1. DS Flags . . . . . . . . . . . . . . . . . . . . . . . . 13 11.1. New Sub-Registries . . . . . . . . . . . . . . . . . . . 14
11.2. Multipath Information Types . . . . . . . . . . . . . . 13 11.1.1. DS Flags . . . . . . . . . . . . . . . . . . . . . . 14
11.3. Entropy Label FEC . . . . . . . . . . . . . . . . . . . 13 11.1.2. Multipath Type . . . . . . . . . . . . . . . . . . . 15
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14 11.2. Entropy Label FEC . . . . . . . . . . . . . . . . . . . 15
13. Contributing Authors . . . . . . . . . . . . . . . . . . . . 14 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 13. Contributing Authors . . . . . . . . . . . . . . . . . . . . 15
14.1. Normative References . . . . . . . . . . . . . . . . . . 14 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
14.2. Informative References . . . . . . . . . . . . . . . . . 14 14.1. Normative References . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14 14.2. Informative References . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction 1. Introduction
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 which can be used by LSP Ping initiator to trace and validate all
ECMP paths between ingress and egress. These encodings are ECMP paths between ingress and egress. These encodings are
sufficient when all the LSRs along the path(s), between ingress and sufficient when all the LSRs along the path(s), between ingress and
egress, consider same set of "keys" as input for load balancing egress, consider same set of "keys" as input for load balancing
algorithm: all IP based or all label based. 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
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sufficient when all the LSRs along the path(s), between ingress and sufficient when all the LSRs along the path(s), between ingress and
egress, consider same set of "keys" as input for load balancing egress, consider same set of "keys" as input for load balancing
algorithm: all IP based or all label based. 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 ELI/EL imposed LSP do not perform o One or more transit LSRs along LSP with ELI/EL in label stack do
ECMP load balancing based on EL (hashes based on "keys" including not perform ECMP load balancing based on EL (hashes based on
IP destination address). This scenario is not only possible but "keys" including IP destination address). This scenario is not
quite common due transit LSRs not implementing [RFC6790] or only possible but quite common due transit LSRs not implementing
transit LSRs implementing [RFC6790] but not implementing suggested [RFC6790] or transit LSRs implementing [RFC6790] but not
transit LSR behavior in Section 4.3 of [RFC6790]. implementing suggested transit LSR behavior in Section 4.3 of
[RFC6790].
o Two or more LSPs stitched together with at least one LSP being ELI o Two or more LSPs stitched together with at least one of these LSP
/EL imposing LSP. Such scenarios are described in pushing ELI/EL in label stack. Such scenarios are described in
[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 FAT Pseudowires is not clearly defined, particularly in the case of Flow-Aware
[RFC6391]. Herein is defined a new FEC Stack sub-TLV for the Entropy Transport Pseudowires [RFC6391]. This document defines a new FEC
Label. Section 3 of this document updates the procedures for Stack sub-TLV for the Entropy Label. Section 3 of this document
multipath information type {9}. updates the procedures for multipath information type {9} described
in [RFC4379] Rest of this document describes extensions required to
restore ECMP discovery and tracing capabilities for scenarios
described.
2. Overview 2. Overview
[RFC4379] describes LSP traceroute as an operation performed through [RFC4379] describes LSP traceroute as an operation where the
initiating LSR sending LSP Ping packet (LSP echo request) with initiating LSR send a series of MPLS echo requests towards the same
incrementing TTL, starting with TTL of one. Initiating LSR discovers destination. The first packet in the series have the TTL set to 1.
and exercises ECMP by obtaining multipath information from each When the echo reply is received from the LSR one hop away the second
transit LSR and using specific destination IP address or specific echo request in the series is sent with the TTL set to 2, for each
entropy label. echo request the TLL is incremented by one until a response is
received from the intended destination. Initiating LSR discovers and
exercises ECMP by obtaining multipath information from each transit
LSR and using specific destination IP address or specific entropy
label.
LSP Ping initiating LSR sends LSP 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 can contain set of IP addresses or set of
labels today. Multipath information types {2, 4, 8} carry set of IP labels today. 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 LSP echo request) is to determine subset Responder LSR (receiver of MPLS echo request) is to determine subset
of initiator specified multipath information which load balances to of initiator specified multipath information which load balances to
each downstream (outgoing interface). Responder LSR sends LSP echo each downstream (outgoing interface). Responder LSR sends MPLS echo
reply with resulting multipath information per downstream (outgoing reply with resulting multipath information per downstream (outgoing
interface) back to the initiating LSR. Initiating LSR is then able interface) back to the initiating LSR. Initiating LSR is then able
to use specific IP destination address or specific label to exercise to use specific IP destination address or specific label to exercise
specific ECMP path on the responder LSR. 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 any of existing multipath information to ELI/ o Initiating LSR sends one of existing multipath information to LSR
EL imposing LSR, but initiating LSR can only continue to discover which pushes ELI/EL in label stack, but initiating LSR can only
and exercise specific path of ECMP if ELI/EL imposing LSR responds continue to discover and exercise specific path of ECMP if LSR
with both IP addresses and associated EL corresponding to each IP which pushes ELI/EL responds with both IP addresses and associated
address. This is because: EL corresponding to each IP address. This is because:
* ELI/EL imposing 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 imposing 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 any of existing multipath information to ELI/ o Initiating LSR sends one of existing multipath information to ELI/
EL imposing 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 imposing LSR responds and exercise specific path of ECMP if ELI/EL pushing LSR responds
with both labels and associated EL corresponding to label. This with both labels and associated EL corresponding to label. This
is because: is because:
* ELI/EL imposing 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 imposes new EL. based on EL from previous LSP and pushes new EL.
* Downstream LSR(s) of ELI/EL imposing 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
LSP echo request/reply packets in Section 8. MPLS echo request/reply packets in Section 8.
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 LSP 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 7.
3. Multipath Type 9 3. Multipath Type 9
[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. First, the
specific location of the label was not defined. What was assumed, specific location of the label was not defined. What was assumed,
but not spelled out, was that the presence of multipath type {9} but not spelled out, was that the presence of multipath type {9}
meant the responder should act as if the payload of the received meant the responder should act as if the payload of the received
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When an MPLS echo request message is received containing a FEC-Stack When an MPLS echo request message is received containing a FEC-Stack
with an EL-FEC at the bottom of the FEC stack and is not preceded by with an EL-FEC at the bottom of the FEC stack and is not preceded by
an entropy label, the responder must behave (for load balancing an entropy label, the responder must behave (for load balancing
purposes) as if the first word of the message were a Pseudowire purposes) as if the first word of the message were a Pseudowire
Control Word. Control Word.
In order to trace a non-FAT pseudowire, instead of including the In order to trace a non-FAT pseudowire, instead of including the
appropriate PW-FEC in the FEC-Stack, an EL-FEC is included. Tracing appropriate PW-FEC in the FEC-Stack, an EL-FEC is included. Tracing
in this way will cause compliant routers to return the proper in this way will cause compliant routers to return the proper
outgoing interface. Note that this procedure only traces to the end outgoing interface. Note that this procedure only traces to the end
of the MPLS transport LSP (e.g. LDP and/or RSVP). To actually verify of the MPLS LSP at transport layer (e.g. LDP and/or RSVP). To
the PW-FEC or in the case of a MS-PW, to determine the next actually verify the PW-FEC or in the case of a MS-PW, to determine
pseudowire label value, the initiator MUST repeat that step of the the next pseudowire label value, the initiator MUST repeat that step
trace, (i.e., repeating the TTL value used) but with the FEC-Stack of the trace, (i.e., repeating the TTL value used) but with the FEC-
modified to contain the appropriate PW-FEC. Stack modified to contain the appropriate PW-FEC.
In order to trace a FAT pseudowire, the initiator includes an EL-FEC In order to trace a Flow-Aware Transport Pseudowire, the initiator
at the bottom of the FEC-Stack and pushes the appropriate PW-FEC onto includes an EL-FEC at the bottom of the FEC-Stack and pushes the
the FEC-Stack. appropriate PW-FEC onto the FEC-Stack.
4. Initiating LSR Procedures 4. 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 imposing ELI/ o When initiating LSR is IP based load balancer (not pushing ELI/
EL), initialize EL_LSP=False. EL), initialize EL_LSP=False.
o When initiating LSR imposes ELI/EL, initialize EL_LSP=True. o When initiating LSR pushes ELI/EL, initialize EL_LSP=True.
o When initiating LSR is transmitting non-zero multipath information o When initiating LSR is transmitting non-zero multipath information
type: type:
If (EL_LSP) initiating LSR MUST use multipath information type * If (EL_LSP) initiating LSR MUST use multipath information type
{10}. {10}.
Else initiating LSR MUST use multipath information type {2, 4, * Else initiating LSR MUST use multipath information type {2, 4,
8, 9}. 8, 9}.
o When initiating LSR is transmitting multipath information type o When 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 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.
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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 5. Responder LSR Procedures
Common Procedures: Responder LSR receiving LSP echo request packet Common Procedures: Responder LSR receiving MPLS echo request packet
with multipath information type {10} MUST validate following 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 responder LSR to consider the
packet as malformed and return code 1 (Malformed echo request packet as malformed and return code 1 (Malformed echo request
received) in LSP echo reply packet. received) in 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 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 Imposing ELI/EL 5.1. IP Based Load Balancer & Not Pushing ELI/EL
o Responder MUST set {L=0, E=0} in DS flags. o 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, responder
MUST comply with [RFC4379]/[RFC6424]. MUST comply with [RFC4379]/[RFC6424].
o If multipath information type {9} is received, responder MUST o If multipath information type {9} is received, 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, responder MUST
reply with multipath information type {10}. "Label Multipath reply with multipath information type {10}. "Label Multipath
Information" and "Associated Label Multipath Information" sections Information" and "Associated Label Multipath Information" sections
MUST be omitted (NULL). If no matching IP address is found, then MUST be omitted (NULL). If no matching IP address is found, then
"IPMultipathType" field MUST be set to multipath information type "IPMultipathType" field MUST be set to multipath information type
{0} and "IP Multipath Information" section MUST also be omitted {0} and "IP Multipath Information" section MUST also be omitted
(NULL). If at least one matching IP address is found, then (NULL). If at least one matching IP address is found, then
"IPMultipathType" field MUST be set to appropriate multipath "IPMultipathType" field MUST be set to appropriate multipath
information type {2, 4, 8} and "IP Multipath Information" section information type {2, 4, 8} and "IP Multipath Information" section
MUST be included. MUST be included.
5.2. IP Based Load Balancer & Imposing ELI/EL 5.2. IP Based Load Balancer & Pushes ELI/EL
o Responder MUST set {L=0, E=1} in DS flags. o Responder MUST set {L=0, E=1} in DS flags.
o If multipath information type {9} is received, responder MUST o If multipath information type {9} is received, 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, responder MUST
respond with multipath type {10}. "Label Multipath Information" respond with multipath type {10}. See Section 8 for details of
section MUST be omitted (NULL). IP address set specified in 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 received IP multipath information MUST be used to determine the
returning IP/Label pairs. If received multipath information type returning IP/Label pairs. If received multipath information type
was {10}, received "Label Multipath Information" sections MUST NOT was {10}, received "Label Multipath Information" sections MUST NOT
be used to determine the associated label portion of returning IP/ be used to determine the associated label portion of returning IP/
Label pairs. If no matching IP address is found, then Label pairs. If no matching IP address is found, then
"IPMultipathType" field MUST be set to multipath information type "IPMultipathType" field MUST be set to multipath information type
{0} and "IP Multipath Information" section MUST be omitted (NULL). {0} and "IP Multipath Information" section MUST be omitted. In
In addition, "Assoc Label Multipath Length" MUST be set to 0, and addition, "Assoc Label Multipath Length" MUST be set to 0, and
"Associated Label Multipath Information" section MUST also be "Associated Label Multipath Information" section MUST also be
omitted (NULL). If at least one matching IP address is found, omitted. If at least one matching IP address is found, then
then "IPMultipathType" field MUST be set to appropriate multipath "IPMultipathType" field MUST be set to appropriate multipath
information type {2, 4, 8} and "IP Multipath Information" section information type {2, 4, 8} and "IP Multipath Information" section
MUST be included. In addition, "Associated Label Multipath MUST be included. In addition, "Associated Label Multipath
Information" section MUST be populated with list of labels Information" section MUST be populated with list of labels
corresponding to each IP address specified in "IP Multipath corresponding to each IP address specified in "IP Multipath
Information" section. "Assoc Label Multipath Length" MUST be set Information" section. "Assoc Label Multipath Length" MUST be set
to appropriate value. to a value representing length in octets of "Associated Label
Multipath Information" field.
5.3. Label Based Load Balancer & Not Imposing ELI/EL 5.3. Label Based Load Balancer & Not Pushing ELI/EL
o Responder MUST set {L=1, E=0} in DS flags. o Responder MUST set {L=1, 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, 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, responder MUST
comply with [RFC4379] /[RFC6424] as updated by Section 3. comply with [RFC4379] /[RFC6424] as updated by Section 3.
o If multipath information type {10} is received, responder MUST o If multipath information type {10} is received, responder MUST
reply with multipath information type {10}. "IP Multipath reply with multipath information type {10}. "IP Multipath
Information" and "Associated Label Multipath Information" sections Information" and "Associated Label Multipath Information" sections
MUST be omitted (NULL). If no matching label is found, then MUST be omitted (NULL). If no matching label is found, then
"LbMultipathType" field MUST be set to multipath information type "LbMultipathType" field MUST be set to multipath information type
{0} and "Label Multipath Information" section MUST also be omitted {0} and "Label Multipath Information" section MUST also be omitted
(NULL). If at least one matching label is found, then (NULL). If at least one matching label is found, then
"LbMultipathType" field MUST be set to appropriate multipath "LbMultipathType" field MUST be set to appropriate multipath
information type {9} and "Label Multipath Information" section information type {9} and "Label Multipath Information" section
MUST be included. MUST be included.
5.4. Label Based Load Balancer & Imposing ELI/EL 5.4. Label Based Load Balancer & Pushes ELI/EL
o Responder MUST set {L=1, E=1} in DS flags. o Responder MUST set {L=1, E=1} in DS flags.
o If multipath information type {2, 4, 8} is received, responder o If multipath information type {2, 4, 8} is received, 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, responder MUST respond with
multipath type {10}. "IP Multipath Information" section MUST be multipath type {10}. "IP Multipath Information" section MUST be
omitted (NULL). Label set specified in received label multipath omitted. Label set specified in received label multipath
information MUST be used to determine the returning Label/Label information MUST be used to determine the returning Label/Label
pairs. If received multipath information type was {10}, received pairs. If received multipath information type was {10}, received
"Label Multipath Information" sections MUST NOT be used to "Label Multipath Information" sections MUST NOT be used to
determine the associated label portion of returning Label/Label determine the associated label portion of returning Label/Label
pairs. If no matching label is found, then "LbMultipathType" pairs. If no matching label is found, then "LbMultipathType"
field MUST be set to multipath information type {0} and "Label field MUST be set to multipath information type {0} and "Label
Multipath Information" section MUST be omitted (NULL). In Multipath Information" section MUST be omitted. In addition,
addition, "Assoc Label Multipath Length" MUST be set to 0, and "Assoc Label Multipath Length" MUST be set to 0, and "Associated
"Associated Label Multipath Information" section MUST also be Label Multipath Information" section MUST also be omitted. If at
omitted (NULL). If at least one matching label is found, then least one matching label is found, then "LbMultipathType" field
"LbMultipathType" field MUST be set to appropriate multipath MUST be set to appropriate multipath information type {9} and
information type {9} and "Label Multipath Information" section "Label Multipath Information" section MUST be included. In
MUST be included. In addition, "Associated Label Multipath addition, "Associated Label Multipath Information" section MUST be
Information" section MUST be populated with list of labels populated with list of labels corresponding to each label
corresponding to each label specified in "Label Multipath specified in "Label Multipath Information" section. "Assoc Label
Information" section. "Assoc Label Multipath Length" MUST be set Multipath Length" MUST be set to a value representing length in
to appropriate value. octets of "Associated Label Multipath Information" field.
5.5. FAT MS-PW Stitching LSR 5.5. FAT MS-PW Stitching LSR
MS-PW stitching LSR that xconnects flow-aware pseudowires behaves in Stitching LSR that xconnects Flow-Aware Transport Pseudowires behave
one of two ways: in one of two ways:
o Load balances on previous flow label, and carries over same flow o Load balances on previous flow label, and carries over same flow
label. For this case, stitching LSR is to behave as procedures label. For this case, stitching LSR is to behave as procedures
described in Section 5.3. described in Section 5.3.
o Load balances on previous flow label, and replaces flow label with 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 5.4.
6. Entropy Label FEC 6. Entropy Label FEC
skipping to change at page 11, line 16 skipping to change at page 11, line 38
Flag Name and Meaning Flag Name and Meaning
---- ---------------- ---- ----------------
L Label based load balance indicator L Label based load balance indicator
This flag MUST be set to zero in the echo request. LSR This flag MUST be set to zero in the echo request. LSR
which performs load balancing on a label MUST set this which performs load balancing on a label MUST set this
flag in the echo reply. LSR which performs load flag in the echo reply. LSR which performs load
balancing on IP MUST NOT set this flag in the echo balancing on IP MUST NOT set this flag in the echo
reply. reply.
E ELI/EL imposer indicator E ELI/EL push indicator
This flag MUST be set to zero in the echo request. LSR This flag MUST be set to zero in the echo request. LSR
which imposes ELI/EL MUST set this flag in the echo which pushes ELI/EL MUST set this flag in the echo
reply. LSR which does not impose ELI/EL MUST NOT set reply. LSR which does not push ELI/EL MUST NOT set
this flag in the echo reply. this flag in the echo reply.
Two flags result in four load balancing techniques which echo reply Two flags result in four load balancing techniques which echo reply
generating LSR can indicate: generating LSR can indicate:
o {L=0, E=0} LSR load balances based on IP and does not impose ELI/ o {L=0, E=0} LSR load balances based on IP and does not push ELI/EL.
EL.
o {L=0, E=1} LSR load balances based on IP and imposes 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 impose o {L=1, E=0} LSR load balances based on label and does not push ELI/
ELI/EL. EL.
o {L=1, E=1} LSR load balances based on label and imposes ELI/EL. o {L=1, E=1} LSR load balances based on label and pushes ELI/EL.
8. New Multipath Information Type: 10 8. 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
section to describe another label set which associates to either IP section to describe another label set which associates to either IP
address set or label set specified in the other section. address set or label set specified in the other section.
Multipath information type 10 has following format: Multipath information type 10 has following format:
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
skipping to change at page 12, line 29 skipping to change at page 12, line 45
| (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) |
~ ~ ~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o IPMultipathType
* 0 when "IP Multipath Information" is omitted. Otherwise one of
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 reuses IP multipath information from [RFC4379].
Specifically, multipath information for values {2, 4, 8} can be
used.
This section reuses IP multipath information from [RFC4379]. o LbMultipathType
Specifically, values {0, 2, 4, 8} can be used.
* 0 when "Label Multipath Information" is omitted. Otherwise
label multipath information value {9}.
o Label Multipath Information o Label Multipath Information
This section reuses label multipath information from [RFC4379]. * This section is omitted when "LbMultipathType" is 0. Otherwise
Specifically, values {0, 9} can be used. this section reuses label multipath information from [RFC4379].
Specifically, multipath information for value {9} can be used.
o Associated Label Multipath Information o Associated Label Multipath Information
"Assoc Label Multipath Length" is a 16 bit field of multipath * "Assoc Label Multipath Length" is a 16 bit field of multipath
information which indicates length in octets of the associated information which indicates length in octets of the associated
label multipath information. label multipath information.
"Associated Label Multipath Information" is a list of labels * "Associated Label Multipath Information" is a list of labels
with each label described in 24 bits. This section MUST be with each label described in 24 bits. This section MUST be
omitted (NULL) in an MPLS Echo Request message. A midpoint omitted in an MPLS echo request message. A midpoint which
which imposes ELI/EL labels SHOULD include "Assoc Label pushes ELI/EL labels SHOULD include "Assoc Label Multipath
Multipath Information" in its MPLS Echo Reply message, along Information" in its MPLS echo reply message, along with either
with either "IP Multipath Information" or "Label Multipath "IP Multipath Information" or "Label Multipath Information".
Information". Each specified associated label described in Each specified associated label described in this section maps
this section maps to specific IP address OR label described in to specific IP address OR label described in the "IP Multipath
the "IP Multipath Information" section or "Label Multipath Information" section or "Label Multipath Information" section.
Information" section. For example, if 3 IP addresses are For example, if 3 IP addresses are specified in the "IP
specified in the "IP Multipath Information" section, then there Multipath Information" section, then there MUST be 3 labels
MUST be 3 labels described in this section. First label maps described in this section. First label maps to the lowest IP
to the lowest IP address specified, second label maps to the address specified, second label maps to the second lowest IP
second lowest IP address specified and third label maps to the address specified and third label maps to the third lowest IP
third lowest IP address specified. address specified.
9. Unsupported Cases 9. Unsupported Cases
There are couple of scenarios where LSP path tracing mechanics are There are couple of scenarios where LSP path tracing mechanics are
not supported in this draft revision. not supported in this draft revision.
o When one or more LSP transit node(s) performs label based load o When one or more LSP transit node(s) performs label based load
balancing on a label that is not bottom-of-stack label when balancing on a label that is not bottom-of-stack label when
Entropy Label Indicator is not included. Entropy Label Indicator is not included.
o When one or more LSP transit node(s) performs label based load o When one or more LSP transit node(s) performs label based load
balancing on a label other than Entropy Label when Entropy Label balancing on a label other than Entropy Label when Entropy Label
Indicator and Entropy Label pair is included. Indicator and Entropy Label pair is included.
10. Security Considerations 10. Security Considerations
Beyond those specified in [RFC4379], [RFC6424] and [RFC6790], there This document extends LSP Traceroute mechanism to discover and
are no further security measured required. exercise ECMP paths when LSP uses ELI/EL in label stack. Additional
processings are required for responder and initiator nodes.
Responder node that pushes ELI/EL will need to compute and return
multipath data including associated EL. 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 as well as in carried multipath information to downstream
nodes. Due to additional processing, it is critical that proper
security measures described in [RFC4379] and [RFC6424] are followed.
11. IANA Considerations 11. IANA Considerations
11.1. DS Flags 11.1. New Sub-Registries
DS flags ... not maintained by IANA. Should it be? [RFC4379] defines the Downstream Mapping TLV, which has the Type 2
assigned from the "Multi-Protocol Label Switching (MPLS) Label
Switched Paths (LSPs) Ping Parameters - TLVs" registry. [RFC6424]
defines the Downstream Detailed Mapping TLV, which has the Type 20
assigned from the "Multi-Protocol Label Switching (MPLS) Label
Switched Paths (LSPs) Ping Parameters - TLVs" registry. Both TLVs
shares two fields: "DS Flags" and "Multipath Type". This document
requires allocation of new values in both the "DS Flags" and
"Multipath Type" fields, which are not maintained by IANA today.
Therefore, this document requests IANA to create new registries
within [IANA-MPLS-LSP-PING] protocol to maintain "DS Flags" and
"Multipath Type" fields. Name of registries and initial values are
described in immediate sub-sections to follow.
11.2. Multipath Information Types 11.1.1. DS Flags
Multipath information types ... not maintained by IANA. Should it Bit number Name Reference
be? ---------- ---------------------------------------- ---------
7 N: Treat as a Non-IP Packet RFC4379
6 I: Interface and Label Stack Object Request RFC4379
5 E: ELI/EL push indicator this document
4 L: Label based load balance indicator this document
3-0 Unassigned
11.3. Entropy Label FEC Assignments of DS Flags are via Standards Action [RFC5226] or IESG
Approval [RFC5226].
IANA is requested to assign a new sub-TLV from the "Sub-TLVs for TLV Note that "DS Flags" is a field included in two TLVs defined in
Types 1 and 16" section from "TLVs" sub-registry within the "Multi- "Multi-Protocol Label Switching (MPLS) Label Switched Paths (LSPs)
Protocol Label Switching (MPLS) Label Switched Paths (LSPs) Ping Ping Parameters - TLVs" registry: Downstream Mapping TLV (value 2)
Parameters" registry. and Downstream Detailed Mapping TLV (value 20). Modification to "DS
Flags" registry will affect both TLVs.
Following value appears to be next available sub-TLV value. 11.1.2. Multipath Type
Requesting IANA to allow specified value as early allocation.
Value Meaning Reference Value Meaning Reference
----- ------- --------- ---------- ---------------------------------------- ---------
26 Entropy Label FEC this document 0 no multipath RFC4379
1 Unassigned
2 IP address RFC4379
3 Unassigned
4 IP address range RFC4379
5-7 Unassigned
8 Bit-masked IP address set RFC4379
9 Bit-masked label set RFC4379
10 IP and label set this document
11-255 Unassigned
Assignments of Multipath Type are via IETF Review [RFC5226] or IESG
Approval [RFC5226].
Note that "Multipath Type" is a field included in two TLVs defined in
"Multi-Protocol Label Switching (MPLS) Label Switched Paths (LSPs)
Ping Parameters - TLVs" registry: Downstream Mapping TLV (value 2)
and Downstream Detailed Mapping TLV (value 20). Modification to
"Multipath Type" registry will affect both TLVs.
11.2. Entropy Label FEC
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)
Label Switched Paths (LSPs) Ping Parameters - TLVs" registry.
Sub-Type Sub-TLV Name Reference
-------- ------------ ---------
TBD1 Entropy Label FEC this document
12. Acknowledgements 12. Acknowledgements
TBD Authors would like to thank Loa Andersson for performing thorough
review and providing valuable comments.
13. Contributing Authors 13. Contributing Authors
Nagendra Kumar Nagendra Kumar
Cisco Systems Cisco Systems
Email: naikumar@cisco.com Email: naikumar@cisco.com
14. References 14. References
14.1. Normative References 14.1. Normative References
skipping to change at page 14, line 39 skipping to change at page 16, line 27
[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 14.2. Informative References
[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-00 (work in progress), February 2013. mpls-01 (work in progress), October 2013.
[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>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[RFC6391] Bryant, S., Filsfils, C., Drafz, U., Kompella, V., Regan, [RFC6391] Bryant, S., Filsfils, C., Drafz, U., Kompella, V., Regan,
J., and S. Amante, "Flow-Aware Transport of Pseudowires J., and S. Amante, "Flow-Aware Transport of Pseudowires
over an MPLS Packet Switched Network", RFC 6391, November over an MPLS Packet Switched Network", RFC 6391, November
2011. 2011.
[RFC6424] Bahadur, N., Kompella, K., and G. Swallow, "Mechanism for [RFC6424] Bahadur, N., Kompella, K., and G. Swallow, "Mechanism for
Performing Label Switched Path Ping (LSP Ping) over MPLS Performing Label Switched Path Ping (LSP Ping) over MPLS
Tunnels", RFC 6424, November 2011. Tunnels", RFC 6424, November 2011.
 End of changes. 70 change blocks. 
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