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Use of Multipath with MPLS and MPLS-TP

The information below is for an old version of the document.
Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 7190.
Author Curtis Villamizar
Last updated 2014-01-23 (Latest revision 2013-11-13)
Replaces draft-villamizar-mpls-multipath-use
RFC stream Internet Engineering Task Force (IETF)
Additional resources Mailing list discussion
Stream WG state Submitted to IESG for Publication
Document shepherd Loa Andersson
Shepherd write-up Show Last changed 2013-11-16
IESG IESG state Became RFC 7190 (Informational)
Consensus boilerplate Yes
Telechat date (None)
Needs a YES.
Responsible AD Adrian Farrel
Send notices to,
IANA IANA review state IANA OK - No Actions Needed
MPLS                                                  C. Villamizar, Ed.
Internet-Draft                         Outer Cape Cod Network Consulting
Intended status: Informational                         November 13, 2013
Expires: May 17, 2014

                 Use of Multipath with MPLS and MPLS-TP


   Many MPLS implementations have supported multipath techniques and
   many MPLS deployments have used multipath techniques, particularly in
   very high bandwidth applications, such as provider IP/MPLS core
   networks.  MPLS-TP has strongly discouraged the use of multipath
   techniques.  Some degradation of MPLS-TP OAM performance cannot be
   avoided when operating over many types of multipath implementations.

   Using MPLS Entropy label, MPLS Label Switched Paths (LSPs) can be
   carried over multipath links while also providing a fully MPLS-TP
   compliant server layer for MPLS-TP LSPs.  This document describes the
   means of supporting MPLS as a server layer for MPLS-TP.  The use of
   MPLS-TP LSPs as a server layer for MPLS LSPs is also discussed.

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Drafts is at

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

   This Internet-Draft will expire on May 17, 2014.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents

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   ( in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Definitions . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  MPLS as a Server Layer for MPLS-TP  . . . . . . . . . . . . .   4
     3.1.  MPLS-TP Forwarding and Server Layer Requirements  . . . .   4
     3.2.  Methods of Supporting MPLS-TP client LSPs over MPLS . . .   6
   4.  MPLS-TP as a Server Layer for MPLS  . . . . . . . . . . . . .   9
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  10
   6.  Implementation Status . . . . . . . . . . . . . . . . . . . .  10
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  11
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  11
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   Today the requirement to handle large aggregations of traffic, can be
   met by a number of techniques which we will collectively call
   multipath.  Multipath applied to parallel links between the same set
   of nodes includes Ethernet Link Aggregation [IEEE-802.1AX], link
   bundling [RFC4201], or other aggregation techniques some of which
   could be vendor specific.  Multipath applied to diverse paths rather
   than parallel links includes Equal Cost MultiPath (ECMP) as applied
   to OSPF, IS-IS, or BGP, and equal cost Label Switched Paths (LSPs).
   Some vendors support load split across equal cost MPLS LSPs where the
   load is split proportionally to the reserved bandwidth of the set of

   RFC 5654 requirement 33 requires the capability to carry a client
   MPLS-TP or MPLS layer over a server MPLS-TP or MPLS layer [RFC5654].
   This is possible in all cases with one exception.  When an MPLS LSP
   exceeds the capacity of any single component link it MAY be carried
   by a network using multipath techniques, but MAY NOT be carried by a
   single MPLS-TP LSP due to the inherent MPLS-TP capacity limitation
   imposed by MPLS-TP Operations, Administration, and Maintenance (OAM)
   fate sharing constraints and MPLS-TP LM OAM packet ordering
   constraints (see Section 3.1).

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   The term composite link is more general than terms such as link
   aggregation (which is specific to Ethernet) or ECMP (which implies
   equal cost paths within a routing protocol).  The use of the term
   composite link here is consistent with the broad definition in
   [ITU-T.G.800].  Multipath is very similar to composite link as
   defined by ITU-T, but specifically excludes inverse multiplexing.

2.  Definitions

   Please refer to the terminology related to multipath introduced in
   [I-D.ietf-rtgwg-cl-requirement].  The following additional terms are
   used in this document with related terms grouped together.

   Link Bundle
       Link bundling is a multipath technique specific to MPLS
       [RFC4201].  Link bundling supports two modes of operations.
       Either an LSP can be placed on one component link of a link
       bundle, or an LSP can be load split across all members of the
       bundle.  There is no signaling defined which allows a per LSP
       preference regarding load split, therefore whether to load split
       is generally configured per bundle and applied to all LSPs across
       the bundle.

   All-Ones Component
       Within the context of link bundling, [RFC4201] defines a special
       case where the same label is to be valid across all component
       links.  This case is indicated in signaling by a bit value of
       "all ones" when identifying a component link.  Following the
       publication of RFC4201, for brevity this special case has been
       referred to as the "all-ones component".

   Equal Cost Multipath (ECMP)
       Equal Cost Multipath (ECMP) is a specific form of multipath in
       which the costs of the links or paths must be equal in a given
       routing protocol.  The load may be split equally across all
       available links (or available paths), or the load may be split
       proportionally to the capacity of each link (or path).

   Loop Free Alternate Paths (LFA)
       "Loop-free alternate paths" (LFA) are defined in RFC 5714,
       Section 5.2 [RFC5714] as follows.  "Such a path exists when a
       direct neighbor of the router adjacent to the failure has a path
       to the destination that can be guaranteed not to traverse the
       failure."  Further detail can be found in [RFC5286].  LFA as
       defined for IPFRR can be used to load balance by relaxing the
       equal cost criteria of ECMP, though IPFRR defined LFA for use in
       selecting protection paths.  When used with IP, proportional
       split is generally not used.  LFA use in load balancing is

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       implemented by some vendors though it may be rare or non-existent
       in deployments.

   Link Aggregation
       The term "link aggregation" generally refers to Ethernet Link
       Aggregation [IEEE-802.1AX] as defined by the IEEE.  Ethernet Link
       Aggregation defines a Link Aggregation Control Protocol (LACP)
       which coordinates inclusion of Link Aggregation Group (LAG)
       members in the LAG.

   Link Aggregation Group (LAG)
       A group of physical Ethernet interfaces that are treated as a
       logical link when using Ethernet Link Aggregation is referred to
       as a Link Aggregation Group (LAG).

   LAG Member
       Ethernet Link Aggregation as defined in [IEEE-802.1AX] refers to
       an individual link in a LAG as a LAG member.  A LAG member is a
       component link.  An Ethernet LAG is a composite link.  IEEE does
       not use the terms composite link or component link.

   A small set of requirements are discussed.  These requirements make
   use of keywords such as MUST and SHOULD as described in [RFC2119].

3.  MPLS as a Server Layer for MPLS-TP

   An MPLS LSP may be used as a server layer for MPLS-TP LSPs as long as
   all MPLS-TP requirements are met.  Section 3.1 reviews the basis for
   requirements of a server layer that supports MPLS-TP as a client
   layer.  Key requirements include OAM "fate-sharing", and the
   requirement that packets within an MPLS-TP LSP are not reordered,
   including both payload and OAM packets.  Section 3.2 discusses
   implied requirements where MPLS is the server layer for MPLS-TP
   client LSPs, and describes a set of solutions using existing MPLS

3.1.  MPLS-TP Forwarding and Server Layer Requirements

   [RFC5960] defines the date plane requirements for MPLS-TP.  Two very
   relevant paragraphs in "Section 3.1.1 LSP Packet Encapsulation and
   Forwarding" are the following.

   RFC5960, Section 3.1.1, Paragraph 3
       Except for transient packet reordering that may occur, for
       example, during fault conditions, packets are delivered in order
       on L-LSPs, and on E-LSPs within a specific ordered aggregate.

   RFC5960, Section 3.1.1, Paragraph 6

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       Equal-Cost Multi-Path (ECMP) load-balancing MUST NOT be performed
       on an MPLS-TP LSP.  MPLS-TP LSPs as defined in this document MAY
       operate over a server layer that supports load-balancing, but
       this load-balancing MUST operate in such a manner that it is
       transparent to MPLS-TP.  This does not preclude the future
       definition of new MPLS-TP LSP types that have different
       requirements regarding the use of ECMP in the server layer.

   [RFC5960] paragraph 3 requires that packets within a specific ordered
   aggregate be delivered in order.  This same requirement is already
   specified by Differentiated Services [RFC2475].  [RFC5960] paragraph
   6 explicitly allows a server layer to use ECMP provided that it is
   transparent to the MPLS-TP client layer.

   [RFC6371] adds a requirement for data traffic and OAM traffic "fate-
   sharing".  The following paragraph in "Section 1 Introduction"
   summarizes this requirement.

   RFC6371, Section 1, Paragraph 7
       OAM packets that instrument a particular direction of a transport
       path are subject to the same forwarding treatment (i.e., fate-
       share) as the user data packets and in some cases, where
       Explicitly TC-encoded-PSC LSPs (E-LSPs) are employed, may be
       required to have common per-hop behavior (PHB) Scheduling Class
       (PSC) End-to-End (E2E) with the class of traffic monitored.  In
       case of Label-Only-Inferred-PSC LSP (L-LSP), only one class of
       traffic needs to be monitored, and therefore the OAM packets have
       common PSC with the monitored traffic class.

   [RFC6371] does not prohibit multilink techniques in "Section 4.6
   Fate-Sharing Considerations for Multilink", where multilink is
   defined as Ethernet Link Aggregation and the use of Link Bundling for
   MPLS, but does declare that such a network would be only partially
   MPLS-TP compliant.  The characteristic that is to be avoided is
   contained in the following sentence in this section.

   RFC6371, Section 4.6, Paragraph 1, last sentence
       These techniques frequently share the characteristic that an LSP
       may be spread over a set of component links and therefore be
       reordered, but no flow within the LSP is reordered (except when
       very infrequent and minimally disruptive load rebalancing

   A declaration that implies that Link Bundling for MPLS yields a
   partially MPLS-TP compliant network, is perhaps overstated since only
   the Link Bundling all-ones component link has this characteristic.

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   [RFC6374] defines a direct Loss Measurement (LM) where LM OAM packets
   cannot be reordered with respect to payload packets.  This will
   require that payload packets themselves not be reordered.  The
   following paragraph in "Section 2.9.4 Equal Cost Multipath" gives the
   reason for this restriction.

   RFC6374, Section 2.9.4, Paragraph 2
       The effects of ECMP on loss measurement will depend on the LM
       mode.  In the case of direct LM, the measurement will account for
       any packets lost between the sender and the receiver, regardless
       of how many paths exist between them.  However, the presence of
       ECMP increases the likelihood of misordering both of LM messages
       relative to data packets and of the LM messages themselves.  Such
       misorderings tend to create unmeasurable intervals and thus
       degrade the accuracy of loss measurement.  The effects of ECMP
       are similar for inferred LM, with the additional caveat that,
       unless the test packets are specially constructed so as to probe
       all available paths, the loss characteristics of one or more of
       the alternate paths cannot be accounted for.

3.2.  Methods of Supporting MPLS-TP client LSPs over MPLS

   Supporting MPLS-TP LSPs over a fully MPLS-TP conformant MPLS LSP
   server layer where the MPLS LSPs are making use of multipath,
   requires special treatment of the MPLS-TP LSPs such that those LSPs
   meet MPLS-TP forwarding requirements (see Section 3.1).  This implies
   the following brief set of requirements.

   MP#1  It MUST be possible for a midpoint MPLS-TP Label Switching
       Router (LSR) which is serving as ingress to a server layer MPLS
       LSP to identify MPLS-TP LSPs, so that MPLS-TP forwarding
       requirements can be applied, or to otherwise accommodate the
       MPLS-TP forwarding requirements.

   MP#2  The ability to completely exclude MPLS-TP LSPs from the
       multipath hash and load split SHOULD be supported.  If the
       selected component link no longer meets requirements, an LSP is
       considered down which may trigger protection and/or may require
       that the ingress LSR select a new path and signal a new LSP.

   MP#3  It SHOULD be possible to insure that MPLS-TP LSPs will not be
       moved to another component link as a result of a composite link
       load rebalancing operation.  If the selected component link no
       longer meets requirements, another component link may be
       selected, however a change in path should not occur solely for
       load balancing.

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   MP#4  Where an Resource Reservation Protocol - Traffic Engineering
       (RSVP-TE) control plane is used, it MUST be possible for an
       ingress LSR which is setting up an MPLS-TP or an MPLS LSP to
       determine at path selection time whether a link or Forwarding
       Adjacency (FA, see [RFC4206]) within the topology can support the
       MPLS-TP requirements of the LSP.

   The reason for requirement MP#1 may not be obvious.  A MPLS-TP LSP
   may be aggregated along with other client LSPs by a midpoint LSR into
   a very large MPLS server layer LSP, as would be the case in a core
   node to core node MPLS LSP between major cities.  In this case the
   ingress of the MPLS LSP, being a midpoint LSR for a set of client
   LSP, has no signaling mechanism that can be used to determine if any
   specific client LSP contained within it is MPLS or MPLS-TP.
   Multipath load splitting can be avoided for MPLS-TP LSP if at the
   MPLS server layer LSP ingress LSR an Entropy Label Indicator (ELI)
   and Entropy Label (EL) are added to the label stack [RFC6790].  For
   those client LSP that are MPLS-TP LSP, a single EL value must be
   chosen.  For those client LSP that are MPLS LSP, per packet entropy
   below the top label must, for practical reasons, be used to determine
   the entropy label value.  Requirement MP#1 simply states that there
   must be a means to make this decision.

   There is currently no signaling mechanism defined to support
   requirement MP#1, though that does not preclude a new extension being
   defined later.  In the absence of a signaling extension, MPLS-TP can
   be identified through some form of configuration, such as
   configuration which provides an MPLS-TP compatible server layer to
   all LSP arriving on a specific interface or originating from a
   specific set of ingress LSR.

   Alternately, the need for requirement MP#1 can be eliminated if every
   MPLS-TP LSP created by an MPLS-TP ingress makes use of an Entropy
   Label Indicator (ELI) and Entropy Label (EL) below the MPLS-TP label
   [RFC6790].  This would require that all MPLS-TP LSR in a deployment
   support Entropy Label, which may render it impractical in many

   Some hardware which exists today can support requirement MP#2.
   Signaling in the absence of MPLS Entropy Label can make use of link
   bundling with the path pinned to a specific component for MPLS-TP LSP
   and link bundling using the all-ones component for MPLS LSP.  This
   prevents MPLS-TP LSP from being carried within MPLS LSP but does
   allow the co-existance of MPLS-TP and very large MPLS LSP.

   MPLS-TP LSPs can be carried as client LSPs within an MPLS server LSP
   if an Entropy Label Indicator (ELI) and Entropy Label (EL) is pushed
   below the server layer LSP label(s) in the label stack, just above

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   the MPLS-TP LSP label entry [RFC6790].  The value of EL can be
   randomly selected at the client MPLS-TP LSP setup time and the same
   EL value used for all packets of that MPLS-TP LSP.  This allows MPLS-
   TP LSP to be carried as client LSP within MPLS LSP and satisfies
   MPLS-TP forwarding requirements but requires that MPLS LSR be able to
   identify MPLS-TP LSP (requirement MP#1).

   MPLS-TP traffic can be protected from degraded performance due to an
   imperfect load split if the MPLS-TP traffic is given queuing priority
   (using strict priority and policing or shaping at ingress or locally
   or weighted queuing locally).  This can be accomplished using the
   Traffic Class field and Diffserv treatment of traffic
   [RFC5462][RFC2475].  In the event of congestion due to load
   imbalance, only non-prioritized traffic will suffer as long as there
   is a low percentage of prioritized traffic.

   If MPLS-TP LSP are carried within MPLS LSP and ELI and EL are used,
   requirement MP#3 is satisfied only for uncongested links where load
   balancing is not required, or if MPLS-TP LSP use TC and Diffserv and
   the load rebalancing implementation rebalances only the less
   preferred traffic.  Load rebalance is generally needed only when
   congestion occurs, therefore restricting MPLS-TP to be carried only
   over MPLS LSP that are known to traverse only links which are
   expected to be uncongested can satisfy requirement MP#3.

   An MPLS-TP LSP can be pinned to a Link Bundle component link if the
   behavior of requirement MP#2 is preferred.  An MPLS-TP LSP can be
   assigned to a Link Bundle but not pinned if the behavior of
   requirement MP#3 is preferred.  In both of these cases, the MPLS-TP
   LSP must be the top level LSP, except as noted above.

   If MPLS-TP LSP can be moved among component links, then the Link
   Bundle all-ones component link can be used or server layer MPLS LSPs
   can be used with no restrictions on the server layer MPLS use of
   multipath except that Entropy Label must be supported along the
   entire path.  An Entropy Label must be used to insure that all of the
   MPLS-TP payload and OAM traffic are carried on the same component,
   except during very infrequent transitions due to load balancing.
   Since the Entropy Label Indicator and Entropy Label are always placed
   above the Generic Associated Channel Label (GAL) in the stack, the
   presense of GAL will not affect the selection of a component link as
   long as the LSR does not hash on the label stack entries below the
   Entropy Label.

   An MPLS-TP LSP may not traverse multipath links on the path where
   MPLS-TP forwarding requirements cannot be met.  Such links include
   any using pre-RFC6790 Ethernet Link Aggregation, pre-RFC6790 Link
   Bundling using the all-ones component link, or other form of

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   multipath not supporting termination of the entropy search at the EL
   label as called for in [RFC6790].  An MPLS-TP LSP must not traverse a
   server layer MPLS LSP which traverses any form of multipath not
   supporting termination of the entropy search at the EL label.  For
   this to occur, the MPLS-TP ingress LSR must be aware of these links.
   This is the reason for requirement MP#4.

   Requirement MP#4 can be supported using administrative attributes.
   Administrative attributes are defined in [RFC3209].  Some
   configuration is required to support this.

4.  MPLS-TP as a Server Layer for MPLS

   Carrying MPLS LSP which are larger than a component link over a MPLS-
   TP server layer requires that the large MPLS client layer LSP be
   accommodated by multiple MPLS-TP server layer LSPs.  MPLS multipath
   can be used in the client layer MPLS.

   Creating multiple MPLS-TP server layer LSP places a greater Incoming
   Label Map (ILM) scaling burden on the LSR.  High bandwidth MPLS cores
   with a smaller amount of nodes have the greatest tendency to require
   LSP in excess of component links, therefore the reduction in number
   of nodes offsets the impact of increasing the number of server layer
   LSP in parallel.  Today, only in cases where deployed LSR ILM are
   small would this be an issue.

   The most significant disadvantage of MPLS-TP as a Server Layer for
   MPLS is that the use MPLS-TP server layer LSP reduces the efficiency
   of carrying the MPLS client layer.  The service which provides by far
   the largest offered load in provider networks is Internet, for which
   the LSP capacity reservations are predictions of expected load.  Many
   of these MPLS LSP may be smaller than component link capacity.  Using
   MPLS-TP as a server layer results in bin packing problems for these
   smaller LSP.  For those LSP that are larger than component link
   capacity, their capacity are not integer multiples of convenient
   capacity increments such as 10Gb/s.  Using MPLS-TP as an underlying
   server layer greatly reduces the ability of the client layer MPLS LSP
   to share capacity.  For example, when one MPLS LSP is underutilizing
   its predicted capacity, the fixed allocation of MPLS-TP to component
   links may not allow another LSP to exceed its predicted capacity.
   Using MPLS-TP as a server layer may result in less efficient use of
   resources and may result in a less cost effective network.

   No additional requirements beyond MPLS-TP as it is now currently
   defined are required to support MPLS-TP as a Server Layer for MPLS.
   It is therefore viable but has some undesirable characteristics
   discussed above.

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5.  Acknowledgements

   Carlos Pignataro, Dave Allan, and Mach Chen provided valuable
   comments and suggestions.  Carlos suggested that MPLS-TP requirements
   in RFC 5960 be explicitly referenced or quoted.  An email
   conversation with Dave led to the inclusion of references and quotes
   from RFC 6371 and RFC 6374.  Mach made suggestions to improve clarity
   of the document.

6.  Implementation Status

   Note: this section is temporary and supports the experiment called
   for in draft-sheffer-running-code.

   This is an informational document which describes usage of MPLS and
   MPLS-TP.  No new protocol extensions or forwarding behavior are
   specified.  Ethernet Link Aggregation and MPLS Link Bundling are
   widely implemented and deployed.

   Entropy Label is not yet widely implemented and deployed, but both
   implementation and deployment are expected soon.  At least a few
   existing high end commodity packet processing chips are capable of
   supporting Entropy Label.  It would be helpful if a few LSR suppliers
   would state their intentions to support RFC 6790 on the MPLS mailing

   Dynamic multipath (multipath load split adjustment in response to
   observed load) is referred to but not a requirement of the usage
   recommendations made in this document.  Dynamic multipath has been
   implemented and deployed, however (afaik) the only core LSR vendor
   supporting dynamic multipath is no longer in the router business
   (Avici Systems).  At least a few existing high end commodity packet
   processing chips are capable of supporting dynamic multipath.

7.  IANA Considerations

   This memo includes no request to IANA.

8.  Security Considerations

   This document specifies requirements with discussion of framework for
   solutions using existing MPLS and MPLS-TP mechanisms.  The
   requirements and framework are related to the coexistence of MPLS/
   GMPLS (without MPLS-TP) when used over a packet network, MPLS-TP, and
   multipath.  The combination of MPLS, MPLS-TP, and multipath does not
   introduce any new security threats.  The security considerations for
   MPLS/GMPLS and for MPLS-TP are documented in [RFC5920] and [RFC6941].

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9.  References

9.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC5654]  Niven-Jenkins, B., Brungard, D., Betts, M., Sprecher, N.,
              and S. Ueno, "Requirements of an MPLS Transport Profile",
              RFC 5654, September 2009.

   [RFC5960]  Frost, D., Bryant, S., and M. Bocci, "MPLS Transport
              Profile Data Plane Architecture", RFC 5960, August 2010.

   [RFC6371]  Busi, I. and D. Allan, "Operations, Administration, and
              Maintenance Framework for MPLS-Based Transport Networks",
              RFC 6371, September 2011.

   [RFC6374]  Frost, D. and S. Bryant, "Packet Loss and Delay
              Measurement for MPLS Networks", RFC 6374, September 2011.

   [RFC6790]  Kompella, K., Drake, J., Amante, S., Henderickx, W., and
              L. Yong, "The Use of Entropy Labels in MPLS Forwarding",
              RFC 6790, November 2012.

9.2.  Informative References

              Villamizar, C., McDysan, D., Ning, S., Malis, A., and L.
              Yong, "Requirements for Advanced Multipath in MPLS
              Networks", draft-ietf-rtgwg-cl-requirement-11 (work in
              progress), July 2013.

              IEEE Standards Association, "IEEE Std 802.1AX-2008 IEEE
              Standard for Local and Metropolitan Area Networks - Link
              Aggregation", 2006, <

              ITU-T, "Unified functional architecture of transport
              networks", 2007, <

   [RFC2475]  Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.,
              and W. Weiss, "An Architecture for Differentiated
              Services", RFC 2475, December 1998.

Villamizar                Expires May 17, 2014                 [Page 11]
Internet-Draft         MPLS and MPLS-TP Multipath          November 2013

   [RFC3209]  Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
              and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
              Tunnels", RFC 3209, December 2001.

   [RFC4201]  Kompella, K., Rekhter, Y., and L. Berger, "Link Bundling
              in MPLS Traffic Engineering (TE)", RFC 4201, October 2005.

   [RFC4206]  Kompella, K. and Y. Rekhter, "Label Switched Paths (LSP)
              Hierarchy with Generalized Multi-Protocol Label Switching
              (GMPLS) Traffic Engineering (TE)", RFC 4206, October 2005.

   [RFC5286]  Atlas, A. and A. Zinin, "Basic Specification for IP Fast
              Reroute: Loop-Free Alternates", RFC 5286, September 2008.

   [RFC5462]  Andersson, L. and R. Asati, "Multiprotocol Label Switching
              (MPLS) Label Stack Entry: "EXP" Field Renamed to "Traffic
              Class" Field", RFC 5462, February 2009.

   [RFC5714]  Shand, M. and S. Bryant, "IP Fast Reroute Framework", RFC
              5714, January 2010.

   [RFC5920]  Fang, L., "Security Framework for MPLS and GMPLS
              Networks", RFC 5920, July 2010.

   [RFC6941]  Fang, L., Niven-Jenkins, B., Mansfield, S., and R.
              Graveman, "MPLS Transport Profile (MPLS-TP) Security
              Framework", RFC 6941, April 2013.

Author's Address

   Curtis Villamizar (editor)
   Outer Cape Cod Network Consulting


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