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Versions: 00 01 02 03 04 05 06 RFC 3564

                                                    Francois Le Faucheur
                                                        Thomas D. Nadeau
                                                     Cisco Systems, Inc.

                                                             Angela Chiu
                                                         Celion Networks

                                                        William Townsend
                                                          Tenor Networks

                                                          Darek Skalecki
                                                         Nortel Networks

                                                           Martin Tatham
                                                                      BT



IETF Internet Draft
Expires: August, 2001
Document: draft-ietf-tewg-diff-te-reqts-00.txt         February, 2001


                      Requirements for support of
                Diff-Serv-aware MPLS Traffic Engineering


Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026. Internet-Drafts are
   Working documents of the Internet Engineering Task Force (IETF), its
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   http://www.ietf.org/ietf/1id-abstracts.txt.
   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.


Abstract

   This document defines the requirements for support of Diff-Serv-
   aware MPLS Traffic Engineering on a per-Class-Type basis, as
   discussed in the Traffic Engineering Working Group Framework
   document [TEWG-FW].


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            Requirements for Diff-Serv Traffic Engineering    Feb 2001

   Companion documents [DIFF-TE-EXT] [DIFF-TE-OSPF] [DIFF-TE-ISIS]
   respectively propose actual extensions to RSVP and CR-LDP, to OSPF
   and to ISIS, in order to meet those requirements.


1.      Introduction

   Diff-Serv is becoming prominent in providing scalable multi-class of
   services in IP networks.

   In some Diff-Serv networks where optimisation of transmission
   resources is not sought, MPLS Traffic Engineering mechanisms may
   simply not be used in complement to Diff-Serv mechanisms.

   In other networks, where some optimisation of transmission resources
   is sought, Diff-Serv mechanisms may be complemented by existing MPLS
   Traffic Engineering mechanisms which operate on an aggregate basis
   across all Diff-Serv Behavior Aggregates. In that case, Diff-Serv
   and MPLS TE both provides their respective benefits (i.e. Diff-Serv
   performs service differentiation at every hop, Traffic Engineering
   achieves better distribution of the aggregate traffic load across
   the set of network resources). However, they would operate
   independently of each other. In other words, MPLS Traffic
   Engineering performs Constraint Based Routing and Admission Control
   with the same set of global constraints for all Behavior Aggregates
   and without the ability to use different sets of constraints for
   different Behavior Aggregates.

   In yet other networks where fine optimisation of transmission
   resources is sought, it is beneficial to perform traffic engineering
   at a per-class level instead of an aggregated level, in order to
   further enhance networks in performance and efficiency. By mapping a
   traffic trunk in a given class on a separate LSP, it allows the
   traffic trunk to utilize resources available to the given class on
   both shortest path(s) and non-shortest paths and follow paths that
   meet constraints which are specific to the given class. This is what
   we refer to as "Diff-Serv-aware Traffic Engineering" and what this
   document focuses on. It also allows each class to select the proper
   protection/restoration mechanism(s) that satisfy its survivability
   requirements in a cost effective manner. Networks where bandwidth is
   scarce (e.g. transcontinental networks), where high priority traffic
   can be significant compared to link speed on some links (e.g. telco
   networks with very large voice trunks), and where the relative
   proportion of traffic across Behavior Aggregates is not uniform
   across the whole topology, are examples of networks where Diff-Serv-
   aware Traffic Engineering can yield significant benefits.

   Besides the set of parameters defined for the general aggregate TE
   [TE-REQ], Diff-Serv-aware Traffic Engineering requires that a new
   set of per-class parameters be provided at each LSR interface and
   (assuming distributed Constraint Based Routing is used) propagated
   via extensions to the IGP (ISIS/OSPF)  [TEWG-FW]. Furthermore, the

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            Requirements for Diff-Serv Traffic Engineering    Feb 2001

   per-class parameters can be aggregated into per-Class-Type
   parameters. The main motivation for grouping a set of classes into a
   Class-Type is to improve the scalability of the IGP link state
   advertisements by propagating information on a per-Class-Type basis
   instead of on a per-class basis. This approach also has the benefit
   of allowing better bandwidth sharing between classes in the same
   Class-Type.

   A Class-Type [TEWG-FW] is defined as a set of classes that satisfy
   the following two conditions:

     1) Classes in the same Class-Type possess common aggregate maximum
       and minimum bandwidth requirements to guarantee the required
       performance level.

     2) There is no maximum or minimum bandwidth requirement to be
       enforced at the level of an individual class within the Class-
       Type. One can still implement some "priority" policies for
       classes within the same Class-Type in terms of accessing the
       Class-Type bandwidth (e.g. via the use of preemption
       priorities).

   An example of Class-Type comprising multiple Diff-Serv classes is a
   low-loss Class-Type that includes both AF1-based and AF2-based
   Ordering Aggregates.

   Note that with per Class-Type TE, Constraint-Based Routing is
   performed with bandwidth constraints on a per Class-Type basis but
   LSPs may carry a single Diff-Serv class (Ordered Aggregate) with
   Diff-Serv scheduling (i.e. PHB) performed separately for each class.

   In this document, we will only discuss "per Class-Type TE" because
   "per Class TE" can be viewed as a special case of per Class-Type TE
   (where each Class-Type is degenerated into a single Diff-Serv
   class).

   This document focuses on intra-domain operations. Inter-domain
   operations is for further study.

   The following sections detail the requirements on OSPF/ISIS, RSVP/
   CR-LDP, Constraint Based Routing, MPLS MIBs, Diff-Serv Scheduling
   and Traffic Mapping for support of MPLS Traffic Engineering on a
   per-Class-Type basis.


2.      Requirements for ISIS/OSPF Extensions

   [OSPF-TE] and [ISIS-TE] define extensions to OSPF and ISIS for
   support of (aggregate) MPLS Traffic Engineering. In this section we
   define the requirements on OSPF and ISIS for support of Diff-Serv
   Traffic Engineering on a per-Class-Type basis. These requirements


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            Requirements for Diff-Serv Traffic Engineering    Feb 2001

   are expected to require further extensions to OSPF and ISIS. Such
   extensions are proposed in [DIFF-TE-OSPF] and [DIFFF-TE-ISIS].

   Given that there are hard limits imposed by ISIS/OSPF TLVs, the TLV
   space must be used frugally. An additional concern is that the
   amount of information advertised by the IGP directly affects the
   scalability of the solution. These considerations strongly influence
   the requirements defined in this section.

   As pointed out in [TEWG-FW], the IGP needs to advertise separate "TE
   information" for each Class-Type. We focus now on detailing what
   this "TE information" should be.

   For Constraint Based Routing to be able to compute paths which
   satisfy different bandwidth constraints for each Class-Type, the IGP
   needs to advertise different "Unreserved Bandwidth" information for
   each Class-Type.

   Moreover, we propose that the preemption attribute defined in [TE-
   REQ] be retained for all Class-Types. We also propose that the
   preemption attributes of setup priority and holding priority retain
   existing semantics, and in particular the preemption should work
   across class-types (i.e. independently of class-types), rather than
   having preemption levels operating only within each class-type.
   Thus, the IGP needs to advertise "Unreserved Bandwidth" at each
   preemption level for each Class-Type. However, we observe that
   within a Class-Type, the "Unreserved Bandwidth" value is often
   identical for multiple preemption levels. Firstly, many practical
   MPLS Traffic Engineering deployments will use less than the maximum
   8 possible levels of preemption. In such cases, the Unreserved
   Bandwidth corresponding to a preemption level which is not used will
   always be equal to the Unreserved Bandwidth for the preemption level
   immediately above (numerically lower). For example, if only
   preemption levels 0,1 and 4 are used in a network, then the
   "Unreserved Bandwidth" for preemption levels 2 and 3 are identical
   to the "Unreserved Bandwidth" for preemption 1, and the "Unreserved
   Bandwidth" for preemption levels 5, 6 and 7 are identical to the
   "Unreserved Bandwidth" for preemption 4. Secondly, even when all 8
   preemption levels are used in the network, whenever there is no TE
   Tunnels actually setup for a given preemption level (for that Class-
   Type) on a given link, the Unreserved Bandwidth corresponding to
   that preemption level will again be equal to the Unreserved
   Bandwidth for the preemption level immediately above (numerically
   lower).

   Thus we propose that the IGP extension encoding includes a
   compression scheme which can efficiently reduce the length of the
   "Unreserved Bandwidth" advertisement (for each Class-Type) whenever
   there are duplicate values across multiple preemption levels.

   For the bandwidth constraints to be effectively different for each
   Class-Type, LSRs need to allow configuration for every link of a

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            Requirements for Diff-Serv Traffic Engineering    Feb 2001

   "Maximum Reservable Bandwidth" for each Class-Type. Clearly, the
   "Unreserved Bandwidth" advertised for each Class-Type takes into
   account the "Maximum Reservable Bandwidth" configured for the
   corresponding Class-Type. Consequently, Constraint Based Routing can
   compute paths for the different Class-Types without receiving the
   "Maximum Reservable Bandwidth" for each Class-Type from the IGP.
   Thus we feel that the IGP need not advertise the Maximum Reservable
   Bandwidth for each Class-Type. We note that the Maximum Reservable
   Bandwidth for each Class-Type could have been used by Constraint
   Based Routing to enhance route computation in some situations (e.g.
   as a tie breaker), but we feel this does not justify the extra
   overhead in IGP advertisement.

   Current IGP extensions for (aggregate) TE [OSPF-TE][ISIS-TE] specify
   advertisement of the Maximum Reservable Bandwidth for (aggregate)
   TE. Note that this document does not propose that this be changed.

   Other TE attributes already advertised by the IGP (i.e.
   administrative group/color, IPv4 interface and neighbor addresses,
   Maximum Link Bandwidth, TE Metric) need not be advertised per Class-
   Type as those will be applicable to all Class-Types. We note that
   additional Metrics beyond the existing IGP Metric and TE Metriccould
   be advertised by the IGP in the future if required to allow
   Constraint Based Routing to base route computation for some LSPs on
   other metric values than those carried in the IGP Metric and in the
   single existing TE Metric.

   We propose to begin by allowing a total of 4 Class-Types (i.e., 3
   beyond the existing one aka. Class-Type 0). This is expected to be
   sufficient for practical deployments in the foreseeable future. As
   an example, a total of three Class-Types already allow support of
   separate bandwidth control for Real-Time, Low-Loss and Best Effort,
   while allowing multiple classes within each Class-Type (e.g. AF1 and
   AF2 flavors of "Low-Loss"). More Class-Types could be defined in the
   future if required.

   Where a Class-Type is not effectively used in a network, it is
   recommended that the corresponding sub-TLV is not included in the IS
   reachability TLV. Therefore, the Class-Types for which "Unreserved
   Bandwidth" is to be advertised in the IGP should be configurable and
   the IGP must allow advertisement of "Unreserved Bandwidth" for any
   subset of the Class-Types.

   Implementations of Diff-Serv Traffic Engineering in compliance with
   this specification MUST support at least a total of 2 Class-Types
   and MAY support a total of 3 or 4 Class-Types.

2.1.    Bandwidth Reservation Scheme

   This section discusses the algorithm for computing the "Unreserved
   Bandwidth" for each Class-Type as a function of:


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            Requirements for Diff-Serv Traffic Engineering    Feb 2001

        - the configurable parameters controlling how link bandwidth
   can be reserved by each Class-Type (in particular in situations
   where Class-Types compete for bandwidth reservation) such as "Max
   Reservable Bandwidth for the Class Type",
        - the already established LSPs of all Class-Types.
   This "Unreserved Bandwidth" for each Class-Type is computed for
   advertisement in the IGP (and therefore used as the per Class-Type
   bandwidth constraint for Constraint Based Routing). The same
   algorithm for computation of "Unreserved Bandwidth" must also be
   used for admission control of Diff-Serv-aware Traffic Engineering
   LSPs at establishment time through RSVP or CR-LDP signalling;
   otherwise persistent deadlock situations could occur whereby
   Constraint Based Routing believes that a given LSP for a given
   Class-Type can be routed through a link but local admission control
   rejects it.

   It is desirable to be able to avoid under-utilizing aggregate
   resource. To achieve this, it is necessary to allow the sum of the
   configurable Maximum Reservable Bandwidth of all Class-Types to be
   larger than a configurable Maximum Reservable Aggregate Bandwidth
   (i.e. aggregate across all Class-Types). At the same time, it is
   desirable to be able to avoid over-utilizing the aggregate resource.
   To achieve this, it is necessary to be able to enforce this Maximum
   Reservable Aggregate Bandwidth; in other words it is necessary to
   ensure that the sum of all LSPs across all Class-Types never exceeds
   the Maximum Reservable Aggregate Bandwidth.

   For example, a 10Gb/s link may be configured to allow:

     - Class-Type 0 (eg: BE) to reserve up to 9 Gb/s
     - Class-Type 1 (eg: real time including EF) to reserve up to 5
       Gb/s
     - Class-Type 2 (eg: low loss including AF1 and AF2) to reserve up
       to 8 Gb/s

   and at the same may be configured to allow:

     - on an aggregate basis, the sum of all Class-Types to reserve up
       to 10 Gb/s.

   Therefore, a path computed by the Constraint Based Routing for an
   LSP of Class-Type N must ensure that this LSP fits within the
   remaining Class-Type N bandwidth AND that this LSP fits within the
   remaining Aggregate bandwidth.


   To achieve this, we propose:
     - that for each Class-Type, the IGP uses the "Unreserved Bandwidth
       for Class-Type N" to directly advertise the amount of bandwidth
       that is effectively useable by Class-Type N. This is computed as
       the smaller of these two values:


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            Requirements for Diff-Serv Traffic Engineering    Feb 2001

           o The Class-Type N bandwidth currently unreserved (i.e. the
             difference between the Maximum Reservable Bandwidth for
             Class-Type N and the bandwidth reserved by existing Class-
             Type N LSPs).
           o The aggregate bandwidth currently unreserved (i.e. the
             difference between the Maximum Reservable Aggregate
             Bandwidth and the bandwidth reserved by existing LSPs of
             all Class-Types).
     - to have Constraint Based Routing ensure that a new Class-Type N
       LSP simply fits in the received "Unreserved Bandwidth for Class-
       Type N".
   Such an approach only requires that N "unreserved bandwidth"
   information be advertised by the IGP when N Class-Types are
   supported, and only requires that the node performing Constraint
   Based Routing meets a single bandwidth constraint.

   It may be desirable to prevent a Class-Type from being starved by
   others. In the example given above where we defined three Class-
   Types, it may be useful to be able to always ensure that some amount
   of Class-Type 0 LSPs can be routed over that link (i.e. to prevent
   Class-Type 1 LSPs and Class-Type 2 LSPs from reserving up to 100% of
   the maximum reservable aggregate bandwidth which would result in
   Class-Type 0 LSPs not having any access to the capacity of that
   link). Such capability might require the ability from the IGP to
   advertise an optional "minimum reservable bandwidth" per Class-Type.
   This is not seen as an immediate requirement but could be defined in
   the future if required.



   [Editor's Note: We are considering a potential enhancement to the
   Bandwidth Reservation scheme presented above and therefore to the
   calculation of advertised `unreserved bandwidth' per Class-Type.
   This would be with the goal of better matching the bandwidth
   "sharing" properties (across Class-Types) of common work-conserving
   Diff-Serv schedulers (e.g. Weighted Fair Queuing). ]



3.      Requirements for RSVP/CR-LDP Extensions

   [RSVP-TE] and [CR-LDP] define extensions to RSVP and LDP for support
   of (aggregate) MPLS Traffic Engineering. [DIFF-MPLS] defines the
   extensions to RSVP and LDP for support of Diff-Serv over MPLS. In
   this section we define the requirements on RSVP and CR-LDP for
   support of Diff-Serv Traffic Engineering on a per-Class-Type basis.
   These requirements are expected to require further extensions to
   RSVP and CR-LDP. Such extensions are proposed in [DIFF-TE-EXT].

   In order for an LSR to perform resource availability checking for an
   LSP that belongs to a certain Class-Type, the LSR needs to be made


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            Requirements for Diff-Serv Traffic Engineering    Feb 2001

   aware through RSVP/CR-LDP signaling of the Class-Type associated
   with the LSP.

   To that end, we propose that RSVP/CR-LDP be extended to be able to
   signal the Class-Type.

   We identify the following backward compatibility requirements for
   the RSVP/CR-LDP extensions:
     - operations in heterogeneous environments need to be supported
       for smooth migration, where some LSRs are Diff-Serv-TE-capable
       (as defined in this specification) while some other LSRs are not
       Diff-Serv-TE-capable (i.e. support (aggregate) TE only)
     - in such heterogeneous environments, the solution needs to allow
       establishment of Class-Type 0 LSPs across paths combining Diff-
       Serv-TE-capable LSRs and non-Diff-Serv-TE-capable LSRs
     - in heterogeneous environments, the solution needs to ensure that
       a non-Diff-Serv-TE-capable LSR would reject establishment of a
       Class-Type N (N=1,2,3) LSP.

   More generally we identify the following backward compatibility
   requirements for the RSVP/CR-LDP extensions:
     - operations in heterogeneous environments need to be supported
       for smooth migration, where some Diff-Serv-TE-capable LSRs (as
       defined in this specification) support N Class-Types while other
       Diff-Serv-TE-capable LSRs support M Class-Types with M>N.
     - in such heterogeneous environments, the solution needs to allow
       establishment of Class-Type 0,.., N-1 LSPs across paths
       combining both types of LSRs
     - in such heterogeneous environments, the solution needs to ensure
       that a Diff-Serv-TE-capable LSR supporting only N Class-Types
       would reject establishment of a Class-Type X LSP if N<=X<=M-1.

   The admission control algorithm implemented for LSP establishment
   must locally maintain different variables which keep track of the
   currently unreserved bandwidth for each Class-Type. These unreserved
   bandwidth variables must be updated in accordance with the Bandwidth
   Reservation Scheme discussed in the previous section.


4.      Requirements for Constraint Based Routing Extensions

   In order for Constraint Based Routing to support Diff-Serv TE on a
   per-Class-Type basis, the Constraint Based Routing algorithm need to
   be capable of taking into account the "Unreserved Bandwidth for
   Class-Type N" when computing a path for a Class-Type N LSP.

   The Constraint Based Routing may also take into account different
   metric for different LSPs. As an example, when computing a path for
   an LSP from a non-real-time Class-Type, the Constraint Based Routing
   may allow use of a metric similar (or equal) to the one currently
   used by IGP SPF Routing for Best Effort traffic, while when
   computing a path for an LSP from a real-time Class-Type, the

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            Requirements for Diff-Serv Traffic Engineering    Feb 2001

   Constraint Based Routing may allow use of a metric reflecting the
   link propagation delay.


5.      Requirements for MIB Extensions

   In order for an LSR to support the configuration and monitoring of
   Diff-Serv Traffic Engineering certain enhancements to some of the
   existing MPLS Management Information Bases (MIBs) will be required.
   [LSRMIB] defines the MPLS Label Switch Router MIB (LSR MIB) which
   contains objects useful for the management and configuration of MPLS
   LSPs. [TE MIB] defines the MPLS Traffic Engineering MIB (TE MIB)
   which contains objects useful for the management and configuration
   of MPLS Traffic Engineered Tunnels.

   In particular, the MIB extensions need to:
     - track for each MPLS interface, the Maximum Reservable Bandwidth
       configured for each Class-Type.
     - track for each MPLS interface, the Maximum Reservable Aggregate
       Bandwidth configured.
     - track for each LSP, the Class-Type associated with the LSP. On
       the Head-End LSRs, the Class-Type is configured as part of the
       tunnel configuration. On other LSRs, the Class-Type is
       associated with the LSP at establishment time based on signaled
       information.

   Additional details of these changes will be provided in forthcoming
   versions of this draft. It is the authors' intent to transfer these
   MIB requirements to future versions of the MPLS TE and the MPLS LSR
   MIBs. It is not the intent of this document to define the SMI
   required for the MIB enhancements; rather, it is to flesh out and
   define the details of these changes in the context of this document.


6.      Diff-Serv Scheduling Requirements

   Diff-Serv-aware Traffic Engineering is expected to be deployed in
   conjunction with Diff-Serv PHBs' buffer management and differential
   packet scheduling. Per-class-type performance would be controlled on
   longer timescales by Diff-Serv-aware Traffic Engineering; this would
   be complemented by Diff-Serv buffer management and differential
   packet scheduling mechanisms controlling the per-class performance
   on packet scheduling timescales.



   We observe that, in order to more accurately control the performance
   actually observed by traffic of a given class depending on the
   current mix of LSPs established for each Class-Type, an LSR may
   offer support of dynamic resource allocation to Classes based on
   per-class LSP resource requests. This effectively results in
   stricter alignment between (i) Diff-Serv-Aware Traffic Engineering

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            Requirements for Diff-Serv Traffic Engineering    Feb 2001

   mechanisms (e.g. resource reservation, admission control) operating
   on longer timescale and (ii) Diff-Serv's buffer management and
   scheduling operating on shorter timescale. This dynamic resource
   adjustment should then take account of the performance requirements
   of the classes. This may be achieved using, for example, per-Class
   maximum allocation multipliers or overbooking factors to adjust
   scheduling weights.


7.      Traffic Mapping Requirements

   This section describes the requirement for an LSR which is the Head-
   end of Diff-Serv-aware Traffic Engineering LSPs to map incoming
   traffic onto these LSPs.
   Each Diff-Serv-aware Traffic Engineering LSP has the following
   attributes:
       - it can transport one (or a set of) Diff-Serv class(es)
       (Ordered Aggregate) in accordance with [DIFF-MPLS]
       - it has been constraint based routed based on the Class-Type
       which comprises this (or these) class(es), in accordance with
       the previous sections of this document.

   Mapping of incoming traffic onto Diff-Serv-aware Traffic Engineering
   LSPs is to be performed in accordance with [DIFF-MPLS] so that only
   packets that belong to the (set of) Behavior Aggregate(s)
   transported over a given Diff-Serv-aware TE LSP should be mapped to
   that LSP. In particular, where the Head-end LSR is also the MPLS
   Edge LSR, determination of the Behavior Aggregate (and thus
   determination of the egress Diff-Serv-aware TE LSP) is based on the
   Diffserv Codepoint (DSCP) in the packet header.


8.      Security Considerations

   The solution developed to address the requirements defined in this
   document must address security aspects.


9.      Acknowledgments

   This document has benefited from discussions with Carol Iturralde
   and Rob Goguen.


References

   [TE-REQ] Awduche et al, Requirements for Traffic Engineering over
   MPLS, RFC2702, September 1999.

   [TEWG-FW] Awduche et al, A Framework for Internet Traffic
   Engineering, draft-ietf-tewg-framework-02.txt, July 2000.


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            Requirements for Diff-Serv Traffic Engineering    Feb 2001


   [DIFF-TE-EXT] Le Faucheur et al, Extensions to RSVP and CR-LDP for
   support of Diff-Serv-aware MPLS Traffic Engineering, draft-ietf-
   mpls-diff-te-ext-01.txt, February 2001.

   [DIFF-TE-OSPF] Le Faucheur et al,  Extension to OSPF for support of
   Diff-Serv-aware MPLS Traffic Engineering, draft-ietf-ospf-diff-te-
   00.txt, February 2001.

   [DIFF-TE-ISIS] Le Faucheur et al,  Extension to ISIS for support of
   Diff-Serv-aware MPLS Traffic Engineering, draft-ietf-isis-diff-
   te00.txt, February 2001.

   [OSPF-TE] Katz, Yeung, Traffic Engineering Extensions to OSPF,
   draft-katz-yeung-ospf-traffic-03.txt, September 2000.

   [ISIS-TE] Smit, Li, IS-IS extensions for Traffic Engineering, draft-
   ietf-isis-traffic-02.txt, September 2000.

   [RSVP-TE] Awduche et al, "RSVP-TE: Extensions to RSVP for LSP
   Tunnels", draft-ietf-mpls-rsvp-lsp-tunnel-07.txt, August 2000.

   [DIFF-MPLS] Le Faucheur et al, "MPLS Support of Diff-Serv", draft-
   ietf-mpls-diff-ext-08.txt, February 2001

   [LDP] Andersson et al., "LDP Specification", draft-ietf-mpls-ldp-
   11.txt, August 2000

   [CR-LDP] Jamoussi et al., "Constraint-Based LSP Setup using LDP",
   draft-ietf-mpls-cr-ldp-04.txt, July 2000

   [TEMIB]     Srinivansan, C., and A. Viswanathan, "MPLS Traffic
   Engineering Management Information Base Using SMIv2", draft-ietf-
   mpls-te-mib-04.txt, July 2000.

   [LSRMIB]    Srinivansan, C., Viswanathan, A., and T. Nadeau "MPLS
   Label Switch Router Management Information Base Using SMIv2", draft-
   ietf-mpls-lsr-mib-06.txt, July 2000.


Authors' Address:

   Francois Le Faucheur
   Cisco Systems, Inc.
   Petra B - Les Lucioles - 291, rue Albert Caquot - 06560 Valbonne -
   France
   Phone: +33 4 92 96 75 64
   Email: flefauch@cisco.com

   Angela Chiu
   Celion Networks
   1 Sheila Drive, Suite 2

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            Requirements for Diff-Serv Traffic Engineering    Feb 2001

   Tinton Falls, NJ 07724
   Phone: +1-732 747 9987
   Email: angela.chiu@celion.com


   William Townsend
   Tenor Networks
   100 Nagog Park
   Acton, MA 01720
   Phone: +1-978-264-4900
   Email: btownsend@tenornetworks.com

   Thomas D. Nadeau
   Cisco Systems, Inc.
   250 Apollo Drive
   Chelmsford, MA 01824
   Phone: +1-978-244-3051
   Email: tnadeau@cisco.com

   Darek Skalecki
   Nortel Networks
   3500 Carling Ave,
   Nepean K2H 8E9
   Phone: +1-613-765-2252
   Email: dareks@nortelnetworks.com

   Martin Tatham
   BT
   Adastral Park,
   Martlesham Heath,
   Ipswich IP5 3RE
   UK
   Phone: +44-1473-606349
   Email: martin.tatham@bt.com



















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