One document matched: draft-davie-tsvwg-rsvp-l3vpn-00.txt




Network Working Group                                           B. Davie
Internet-Draft                                            F. le Faucheur
Intended status: Standards Track                            A. Narayanan
Expires: January 1, 2008                             Cisco Systems, Inc.
                                                           June 30, 2007


                    Support for RSVP in Layer 3 VPNs
                  draft-davie-tsvwg-rsvp-l3vpn-00.txt

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Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract

   RFC 4364 defines an approach to building provider-provisioned Layer 3
   VPNs.  It may be desirable to use RSVP to perform admission control
   on the links between CE and PE routers.  This document specifies
   procedures by which RSVP messages travelling from CE to CE across an
   L3VPN may be appropriately handled by PE routers so that admission
   control can be performed on PE-CE links.  Optionally, admission
   control across the provider's backbone may also be supported.



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Requirements Language

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


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Problem Statement  . . . . . . . . . . . . . . . . . . . . . .  4
     2.1.  Model of Operation . . . . . . . . . . . . . . . . . . . .  5
   3.  Admission Control on PE-CE Links . . . . . . . . . . . . . . .  6
     3.1.  Path Message Processing at Ingress PE  . . . . . . . . . .  6
     3.2.  Path Message Processing at Egress PE . . . . . . . . . . .  8
     3.3.  Resv Processing at Egress PE . . . . . . . . . . . . . . .  9
     3.4.  Resv Processing at Ingress PE  . . . . . . . . . . . . . .  9
     3.5.  Other RSVP Messages  . . . . . . . . . . . . . . . . . . .  9
   4.  Admission Control in Provider's Backbone . . . . . . . . . . . 10
   5.  Object Definitions . . . . . . . . . . . . . . . . . . . . . . 11
     5.1.  VPN_Label Object . . . . . . . . . . . . . . . . . . . . . 11
     5.2.  VRF_ID Object  . . . . . . . . . . . . . . . . . . . . . . 11
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 11
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 12
   8.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 13
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 13
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 13
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14
   Intellectual Property and Copyright Statements . . . . . . . . . . 16




















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1.  Introduction

   [RFC4364] defines a Layer 3 VPN service known as BGP/MPLS VPNs.
   [RFC2205] defines the Resource Reservation Protocol (RSVP) which may
   be used to perform admission control as part of the Integrated
   Services (int-serv) architecture [RFC1633][RFC2210].

   Customers of a layer 3 VPN service may run RSVP for the purposes of
   admission control in their own networks.  Since the links between
   Provider Edge (PE) and Customer Edge (CE) routers in a layer 3 VPN
   may often be resource constrained, it may be desirable to be able to
   perform admission control over those links.  In order to perform
   admission control using RSVP in such an environment, it is necessary
   that RSVP control messages, such as Path messages and Resv messages,
   are appropriately handled by the PE routers.  This presents a number
   of challenges in the context of BGP/MPLS VPNs:

   o  RSVP Path message processing depends on routers recognizing the
      router alert option in the IP header.  However, packets traversing
      the backbone of a BGP/MPLS VPN are MPLS encapsulated and thus the
      router alert option is not normally visible to the egress PE.

   o  BGP/MPLS VPNs support non-unique addressing of customer networks.
      Thus a PE at the ingress or egress of the provider backbone may be
      called upon to process Path messages from different customer VPNs
      with non-unique destination addresses.

   o  A PE at the ingress of the provider's backbone may receive Resv
      messages corresponding to different customer VPNs from other PEs,
      and needs to be able to associate those Resv messages with the
      appropriate customer VPNs.

   This document describes a set of procedures to overcome these
   challenges and thus to enable admission control using RSVP over the
   PE-CE links.  We note that similar techniques may be applicable to
   other protocols used for admission control such as NSIS [RFC4080].

   Additionally, it may be desirable to perform admission control over
   the provider's backbone on behalf of one or more L3VPN customers.
   Core (P) routers in a BGP/MPLS VPN do not have forwarding entries for
   customer routes, and thus cannot natively process RSVP messages for
   customer flows.  Also the core is a shared resource that carries
   traffic for many customers, so issues of resource allocation among
   customers and trust (or lack thereof) must also be addressed.  This
   draft also specifies procedures for supporting such a scenario.

   This draft deals with establishing reservations for unicast flows
   only.  Because the support of multicast traffic in BGP/MPLS VPNs is



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   still evolving, and raises additional challenges for admission
   control, we leave the support of multicast flows for further study at
   this point.

1.1.  Terminology

   This document draws freely on the terminology defined in [RFC2205]
   and [RFC4364].  For convenience, we provide a few brief definitions
   here:

   o  CE (Customer Edge) Router: Router at the edge of a customer site
      that attaches to the network of the VPN provider.

   o  PE (Provider Edge) Router: Router at the edge of the service
      provider's network that attaches to one or more customer sites.

   o  VPN Label: An MPLS label associated with a route to a customer
      prefix in a VPN (also called a VPN route label).

   o  VRF: VPN Routing and Forwarding Table.  A PE typically has
      multiple VRFs, enabling it to be connected to CEs that are in
      different VPNs.


2.  Problem Statement

   The problem space of this document is the support of admission
   control between customer sites when the customer subscribes to a BGP/
   MPLS VPN.  We subdivide the problem into (a) the problem of admission
   control on the PE-CE links (in both directions), and (b) the problem
   of admission control across the provider's backbone.

   For the PE-CE link subproblem, the most basic challenge is that RSVP
   control messages contain IP addresses that are drawn from the
   customer's address space, and PEs must be able to deal with traffic
   from many customers who may have non-unique (or overlapping) address
   spaces.  Thus, it is essential that a PE be able in all cases to
   identify the correct VPN context in which to process an RSVP control
   message.  Much of this draft deals with this issue.

   For the case of making reservations across the provider backbone, we
   observe that BGP/MPLS VPNs do not create any per-customer forwarding
   state in the P (provider core) routers.  Thus, in order to make
   reservations on behalf of customer-specified flows, it is clearly
   necessary to make some sort of aggregated reservation from PE-PE and
   then map individual, customer-specific reservations onto an aggregate
   reservation.  That is similar to the problem tackled in [RFC3175] and
   [RFC4804], with the additional complications of handling customer-



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   specific addressing associated with BGP/MPLS VPNs.

   Finally, we note that RSVP Path messages are normally addressed to
   the destination of a session, and contain the router alert IP option.
   Routers along the path to the destination that are configured to
   process RSVP messages must detect the presence of the router alert
   option to allow them to intercept Path messages.  However, the egress
   PEs of a network supporting BGP/MPLS VPNs receive packets destined
   for customer sites as MPLS-encapsulated packets, and normally forward
   based only on examination of the MPLS label.  Hence, a Path message
   would typically be forwarded without examination of the IP options
   and would therefore not receive appropriate processing at the PE.
   This problem of recognizing and processing Path messages is also
   discussed below.

2.1.  Model of Operation

   Figure 1 illustrates the basic model of operation with which this
   document is concerned.


                      --------------------------
                     /       Provider           \
        |----|      |         Backbone           |      |----|
Sender->| CE1|  |-----|                       |-----|   |CE2 |->Receiver
        |    |--|     |   |---|     |---|     |     |---|    |
        |----|  |     |   | P |     | P |     |     |   |----|
                | PE1 |---|   |-----|   |-----| PE2 |
                |     |   |   |     |   |     |     |
                |     |   |---|     |---|     |     |
                |-----|                       |-----|
                    |                            |
                     \                          /
                      --------------------------


   Figure 1.  Model of Operation for RSVP-based admission control over
   MPLS/BGP VPN

   To establish a unidirectional reservation for a point-to-point flow
   from Sender to Receiver that takes account of resource availability
   on the CE-PE and PE-CE links only, the following steps must take
   place:

   1.   Sender sends a Path message to an IP address of the Receiver.

   2.   Path message is processed by CE1 using normal RSVP procedures
        and forwarded towards the Receiver along the link CE1-PE1.



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   3.   PE1 processes Path message and forwards towards the Receiver
        across the provider backbone.

   4.   PE2 processes Path message and forwards towards the Receiver
        along link PE2-CE2.

   5.   CE2 processes Path message using normal RSVP procedures and
        forwards towards Receiver.

   6.   Receiver sends Resv message to CE2.

   7.   CE2 sends Resv message to PE2.

   8.   PE2 processes Resv message (including performing admission
        control on link PE2-CE2) and sends Resv to PE1.

   9.   PE1 processes Resv message and sends Resv to CE1.

   10.  CE1 processes Resv using normal RSVP procedures, performs
        admission control on the link CE1-PE1 and sends Resv message to
        Sender if successful.

   In each of the steps involving Resv messages (6 through 10) the node
   sending the Resv uses the previously established Path state to
   determine the "RSVP Previous Hop (PHOP)" and sends a Resv message to
   that address.  We note that establishing that Path state correctly at
   PEs is one of the challenges posed by the BGP/MPLS environment.


3.  Admission Control on PE-CE Links

   In the following sections we trace through the steps outlined in
   Section 2.1 and expand on the details for those steps where standard
   RSVP procedures need to be extended or modified to support the BGP/
   MPLS VPN environment.  For all the remaining steps described in the
   preceding section, standard RSVP processing rules apply.

3.1.  Path Message Processing at Ingress PE

   When a Path message arrives at the ingress PE (step 3 of Section 2.1)
   the PE needs to establish suitable Path state and forward the Path
   message on to the egress PE.  In the following paragraphs we
   described the steps taken by the ingress PE.

   The Path message is addressed to the eventual destination (the
   receiver at the remote customer site) and carries the IP Router Alert
   option, in accordance with [RFC2205].  The ingress PE must recognize
   the router alert, intercept these messages and process them as RSVP



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   signalling messages.

   As noted above, there is an issue in recognizing Path messages as
   they arrive at the egress PE (PE 2 in Figure 1).  Since standard Path
   messages carry the router alert IP option, one possible approach
   would be to use the MPLS router alert label [RFC3032] when sending a
   Path message from ingress PE to egress PE.  However this may suffer
   from problems of backwards compatibility with existing deployed
   hardware that may not process the Router Alert label.  The preferred
   approach proposed here is to address the Path messages sent by the
   ingress PE directly to the egress PE; that is, rather than using the
   ultimate receiver's destination address as the destination address of
   the Path message, we use the loopback address of the egress PE as the
   destination address of the Path message.  This approach has the
   advantage that it does not require any new data plane capabilities
   for the egress PE beyond those of a standard BGP/MPLS VPN PE.
   Details of the processing of this message at the egress PE are
   described below.  The approach of addressing a Path message directly
   to an RSVP next hop that is not the next IP hop is already used in
   other environments such as those of [RFC4206] and [RFC4804].

   The details of operation at the ingress PE are as follows.  When the
   ingress PE (PE1 in Figure 1) receives a Path message from CE1 that is
   addressed to the receiver, the VRF that is associated with the
   incoming interface is identified, just as for normal data path
   operations.  The Path state for the session is stored, and is
   associated with that VRF, so that potentially overlapping addresses
   among different VPNs do not appear to belong to the same session.
   The destination address of the receiver is looked up in the
   appropriate VRF, and the BGP Next-Hop for that destination is
   identified.  That next-hop is the egress PE (PE2 in Figure 1).  The
   VPN label for that destination is obtained and placed in a new RSVP
   object (VPN_LABEL, defined below.)  A new Path message is constructed
   with a destination address equal to the address of the egress PE
   identified above.  This new Path message will contain all the objects
   from the original Path message, plus the VPN_LABEL object.  Note that
   the SESSION object contains the ultimate (customer) destination
   address of the flow, while the IP header for the message contains the
   address of the egress PE.  In order to ensure that Resv messages that
   will be sent to the ingress PE by the egress PE can be associated
   with the correct VPN context, the Path message also needs to contain
   an identifier that can be used to identify a VRF.  The VRF_ID object
   is defined below, and is used to carry a locally significant VRF
   identifier.  The VRF identifier needs to be meaningful only to the PE
   that creates this object.






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3.2.  Path Message Processing at Egress PE

   When a Path message arrives at the egress PE, it is addressed to the
   PE itself, and is handed to RSVP for processing.  The router needs to

   a.  Determine the egress VRF for this flow, and how to forward a Path
       message on towards the correct CE and ultimate destination;

   b.  Store the information received in the Path message (including the
       VRF_ID Object);

   c.  Construct a suitable Path message with the correct destination
       address and forward it.

   For step a, we can imagine the router containing an RSVP module and a
   forwarding path module (this division is for exposition only; there
   is no intention to specify the internal implementation here).  The
   RSVP module extracts the MPLS label contained in the VPN_LABEL
   object, and the destination IP address contained in the SESSION
   object, and passes them to the normal forwarding path code for MPLS-
   encapsulated packets.  The forwarding path returns to RSVP the
   outgoing interface information, including the egress VRF, that would
   have been used had a packet with that MPLS label and IP address been
   received.  (Note that in many cases the MPLS label alone is all that
   is needed to determine the forwarding information for the packet, but
   in some cases it is necessary to pop the label and examine the IP
   address; hence both are passed to the forwarding code.)

   Step b proceeds as follows.  Note that [RFC2205] identifies the
   fields in the SESSION object to define a session, specifically the
   destination address, protocol and destination port.  In this draft,
   we can consider the identity of the egress VRF that was determined in
   step a also to be part of the session definition.  The identity of
   this egress VRF is therefore stored with the Path state to facilitate
   processing of Resv messages for this session.

   Now the RSVP module can construct a Path message which differs from
   the Path it received in the following ways:

   a.  Its destination address is the IP address extracted from the
       SESSION Object;

   b.  It does not contain the VPN_LABEL Object or the VRF_ID Object.

   c.  The RSVP_HOP Object contains the IP address of the outgoing
       interface of the egress PE and an LIH, as per normal RSVP
       processing.




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   The router then sends the Path message on towards its destination
   over the interface identified above.

3.3.  Resv Processing at Egress PE

   When a receiver at the customer site originates a Resv message for
   the session, normal RSVP procedures apply until the Resv, making its
   way back towards the sender, arrives at the "egress" PE (it is
   "egress" with respect to the direction of data flow, i.e.  PE2 in
   figure 1).  On arriving at PE2, the SESSION and FILTER objects in the
   Resv, and the VRF in which the Resv was received, are used to find
   the matching Path state stored previously.  At this stage, admission
   control can be performed on the PE-CE link.

   Assuming admission control is successful, the PE constructs a Resv
   message to send to the ingress PE (PE1 in Figure 1).  It includes the
   VRF_ID object that was obtained from the Path message as described
   above.  The Resv message is addressed to the ingress PE and sent.

   If admission control is not successful, a ResvError message is sent
   towards the receiver as per normal RSVP processing.

3.4.  Resv Processing at Ingress PE

   Upon receiving a Resv message at the ingress PE (with respect to data
   flow, i.e.  PE1 in Figure 1), the PE extracts the VRF identifier from
   VRF_ID object and determines which VRF the session is associated
   with.  It is now possible to locate the appropriate Path state for
   the reservation, and generate a Resv message to send to the
   appropriate CE.  Since we assume in this section that admission
   control over the Provider's backbone is not needed, the ingress PE
   does not perform any admission control for this reservation.

3.5.  Other RSVP Messages

   Processing of PathError, PathTear, ResvTear and ResvConfirm messages
   is generally straightforward and follows the rules of [RFC2205].
   However, for such messages going between the ingress and egress PEs,
   two additional rules must be observed:

   o  The VRF_ID must be included in the message;

   o  The message must be directly addressed to the appropriate PE,
      without using the IP Router Alert option.

   Note that ResvError messages do not carry the Router Alert IP option,
   and can be sent to the receiver as standard IP datagrams, and hence
   no special processing other than normal VPN forwarding is needed at



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   the PEs for these messages.

   Note: a future version of this draft will cover error cases in more
   detail.


4.  Admission Control in Provider's Backbone

   The preceding section outlines how per-customer reservations can be
   made over the PE-CE links.  This may be sufficient in many situations
   where the backbone is well engineered with ample capacity and there
   is no need to perform any sort of admission control in the backbone.
   However, in some cases, such as during failures or unanticipated
   periods of overload, it may be desirable to be able to perform
   admission control in the backbone on behalf of customer traffic.

   Because of the fact that routes to customer addresses are not present
   in the P routers, along with the concerns of scalability that would
   arise if per-customer reservations were allowed in the P routers, it
   is clearly necessary to map the per-customer reservations described
   in the preceding section onto some sort of aggregate reservations.
   Furthermore, customer data packets need to be tunneled across the
   provider backbone just as in normal BGP/MPLS VPN operation.

   Given these considerations, a feasible way to achieve the objective
   of admission control in the backbone is to use the ideas described in
   [RFC4804].  MPLS-TE tunnels can be established between PEs as a means
   to perform aggregate admission control in the backbone.

   An MPLS-TE tunnel from an ingress PE to an egress PE can be thought
   of as a virtual link of a certain capacity.  The main change to the
   procedures described above is that when a Resv is received at the
   ingress PE, an admission control decision can be performed by
   checking whether sufficient capacity of that virtual link remains
   available to admit the new customer reservation.

   To achieve effective admission control in the backbone, there needs
   to be some way to separate the data plane traffic that has a
   reservation from that which does not.  We assume that packets that
   are subject to admission control on the core will be given a
   particular MPLS EXP value, and that no other packets will be allowed
   to enter the core with this value unless they have passed admission
   control.  Some fraction of link resources will be allocated to queues
   on core links for packets bearing that EXP value, and the MPLS-TE
   tunnels will use that resource pool to make their constraint-based
   routing and admission control decisions.  This is all consistent with
   the principles of aggregate RSVP reservations described in [RFC3175].




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5.  Object Definitions

5.1.  VPN_Label Object

   The usage of the VPN_LABEL Object is described in Section 3.1 and
   Section 3.2.  The VPN_LABEL object should appear in all RSVP messages
   that contain a SESSION object and are sent from ingress PE to egress
   PE, with the exception of ResvError messages.  (As noted above,
   ResvError messages are sent as normal IP datagrams and not processed
   at the egress PE by RSVP.)  The object MUST NOT be included in any
   RSVP messages that are sent outside of the provider's backbone.  The
   format of the object is as follows:


            VPN_LABEL object: Class = TBA, C-Type = 1

              +-------------+-------------+-------------+-------------+
              |  Reserved(12 bits) |  Label (20 bits)                 |
              +-------------+-------------+-------------+-------------+

   The Reserved bits must be set to zero on transmission and ignored on
   receipt.

5.2.  VRF_ID Object

   The usage of the VRF_ID Object is described in Section 3.  The VRF_ID
   object is a locally significant opaque value.  The object is inserted
   into RSVP messages that carry a SESSION object, and that travel
   between the Ingress and Egress PEs with the exception of ResvError
   messages.  (As noted above, ResvError messages are sent as normal IP
   datagrams and not processed at the egress PE by RSVP.)  It MUST NOT
   be included in any RSVP messages that are sent outside of the
   provider's backbone.  The format of the object is as follows:


            VRF_ID object: Class = TBA, C-Type = 1

              +-------------+-------------+-------------+-------------+
              |          VRF_ID (32 bits)                             |
              +-------------+-------------+-------------+-------------+


6.  IANA Considerations

   This document requires IANA assignment of two new RSVP Class Numbers
   to accommodate the new objects described in Section 5.  These should
   be assigned from the range 0x11bbbbbb, so that they will be ignored
   but forwarded by routers that do not understand them.



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7.  Security Considerations

   [RFC4364] addresses the security considerations of BGP/MPLS VPNs in
   general.  General RSVP security considerations are addressed in
   [RFC2205].  To ensure the integrity of RSVP, the RSVP Authentication
   mechanisms defined in [RFC2747] and [RFC3097]may be used.  These
   protect RSVP message integrity hop-by-hop and provide node
   authentication as well as replay protection, thereby protecting
   against corruption and spoofing of RSVP messages.  [Behringer]
   discusses applicability of various keying approaches for RSVP
   Authentication.  We note that the RSVP signaling in MPLS VPN is
   likely to spread over multiple administrative domains (e.g. the
   service provider operating the VPN service, and the customers of the
   service).  Therefore the considerations in [Behringer] about inter-
   domain issues are likely to apply.

   Beyond those general issues, two specific issues are introduced by
   this document: resource usage on PEs, and resource usage in the
   provider backbone.  We discuss these in turn.

   A customer who makes resource reservations on the CE-PE links for his
   sites is only competing for link resources with himself, as in
   standard RSVP, at least in the common case where each CE-PE link is
   dedicated to a single customer.  Thus, from the perspective of the
   CE-PE links, this draft does not introduce any new security issues.
   However, because a PE typically serves multiple customers, there is
   also the possibility that a customer might attempt to use excessive
   computational resources on a PE (CPU cycles, memory etc.) by sending
   large numbers of RSVP messages to a PE.  In the extreme this could
   represent a form of denial-of-service attack.  In order to prevent
   such an attack, a PE should have mechanisms to limit the fraction of
   its processing resources that can be consumed by any one CE or by the
   set of CEs of a given customer.  For example, a PE might implement a
   form of rate limiting on RSVP messages that it receives from each CE.

   The second concern arises only when the service provider chooses to
   offer resource reservation across the backbone, as described in
   Section 4.  In this case, the concern may be that a single customer
   might attempt to reserve a large fraction of backbone capacity,
   perhaps with a co-ordinated effort from several different CEs, thus
   denying service to other customers using the same backbone.
   [RFC4804] provides some guidance on the security issues when RSVP
   reservations are aggregated onto MPLS tunnels, which are applicable
   to the situation described here.  We note that a provider may use
   local policy to limit the amount of resources that can be reserved by
   a given customer from a particular PE, and that a policy server could
   be used to control the resource usage of a given customer across
   multiple PEs if desired.



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8.  Acknowledgments

   Thanks to Ashwini Dahiya, Prashant Srinivas and Manu Pathak for their
   many contributions to solving the problems described in this draft.


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.

   [RFC2205]  Braden, B., Zhang, L., Berson, S., Herzog, S., and S.
              Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
              Functional Specification", RFC 2205, September 1997.

   [RFC4364]  Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
              Networks (VPNs)", RFC 4364, February 2006.

   [RFC4804]  Le Faucheur, F., "Aggregation of Resource ReSerVation
              Protocol (RSVP) Reservations over MPLS TE/DS-TE Tunnels",
              RFC 4804, February 2007.

9.2.  Informative References

   [Behringer]
              Behringer, M. and F. le Faucheur, "A framework for RSVP
              security using dynamic group keying", July 2007.

              draft-behringer-tsvwg-rsvp-security-groupkeying-00.txt.
              Work in Progress

   [RFC1633]  Braden, B., Clark, D., and S. Shenker, "Integrated
              Services in the Internet Architecture: an Overview",
              RFC 1633, June 1994.

   [RFC2210]  Wroclawski, J., "The Use of RSVP with IETF Integrated
              Services", RFC 2210, September 1997.

   [RFC2747]  Baker, F., Lindell, B., and M. Talwar, "RSVP Cryptographic
              Authentication", RFC 2747, January 2000.

   [RFC3032]  Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
              Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
              Encoding", RFC 3032, January 2001.

   [RFC3097]  Braden, R. and L. Zhang, "RSVP Cryptographic



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              Authentication -- Updated Message Type Value", RFC 3097,
              April 2001.

   [RFC3175]  Baker, F., Iturralde, C., Le Faucheur, F., and B. Davie,
              "Aggregation of RSVP for IPv4 and IPv6 Reservations",
              RFC 3175, September 2001.

   [RFC4080]  Hancock, R., Karagiannis, G., Loughney, J., and S. Van den
              Bosch, "Next Steps in Signaling (NSIS): Framework",
              RFC 4080, June 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.

   [RFC4860]  Le Faucheur, F., Davie, B., Bose, P., Christou, C., and M.
              Davenport, "Generic Aggregate Resource ReSerVation
              Protocol (RSVP) Reservations", RFC 4860, May 2007.


Authors' Addresses

   Bruce Davie
   Cisco Systems, Inc.
   1414 Mass. Ave.
   Boxborough, MA  01719
   USA

   Email: bsd@cisco.com


   Francois le Faucheur
   Cisco Systems, Inc.
   Village d'Entreprise Green Side - Batiment T3
   400, Avenue de Roumanille
   Biot Sophia-Antipolis  06410
   France

   Email: flefauch@cisco.com












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   Ashok Narayanan
   Cisco Systems, Inc.
   1414 Mass. Ave.
   Boxborough, MA  01719
   USA

   Email: ashokn@cisco.com












































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