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      RSVP Receiver Proxy                                        October 1999
      Network Working Group                             Silvano Gai
      Internet Draft                                    Dinesh Dutt
      draft-sgai-rsvp-proxy-00.txt                      Nitsan Elfassy
      Expiration Date: April 2000                       Cisco Systems
                                                        Yoram Bernet
                                                        October 1999
                                 RSVP Receiver Proxy
      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 areas, and its working groups. Note that other
        groups may also distribute working documents as Internet-Drafts.
        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."
        The list of current Internet-Drafts can be accessed at
        http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-
        Draft Shadow Directories can be accessed at
        Distribution of this memo is unlimited.
      Copyright Notice
        Copyright (C) The Internet Society (1998).  All Rights Reserved.
        Gai, Dutt, Elfassy, Bernet                                  [Page 1]

      RSVP Receiver Proxy                                        October 1999
        RSVP has been extended in several directions [Policy], [Identity],
        [DCLASS], [AggrRSVP], [DiffModel],[COPS-RSVP], These extensions have
        broadened the applicability of RSVP characterizing it as a signaling
        protocol usable outside the IntServ model.
        With the addition of the "Null Service Type" [NullServ], RSVP is
        being adopted also by mission critical applications that require some
        form of prioritized service, but cannot readily specify their
        resource requirements. These applications do not need to set-up a
        reservation end-to-end, but only to signal to the network their
        policy information [Policy], [Identity] and obtain in response an
        applicable DSCP [DCLASS].
        RSVP Receiver Proxy is an extension to the RSVP message processing
        (not to the protocol itself), mainly designed to operate in
        conjunction with the Null Service Type and with an extension of the
        COPS for RSVP protocol [COPS-RSVP-EXT].
      Table of contents
        1. Introduction .....................................................3
        2. An overview of RSVP Receiver Proxy ...............................5
        3. Detailed description of the message processing ...................6
        4. The role of the policy server ....................................8
           4.1 Generation of the Resv message by the Receiver Proxy..........8
           4.2 Communication With the Policy Server..........................9
           4.3 Enhancements To Existing Infrastructure......................10
           4.4 Processing of other RSVP messages............................10
        5. RSVP With Null Service Type .....................................11
        6. Security Considerations .........................................11
        7. Intellectual Property Considerations ............................11
        8. References ......................................................12
        9. Author Information ..............................................14
        10. Full Copyright Statement .......................................15
        Gai, Dutt, Elfassy, Bernet                                  [Page 2]

      RSVP Receiver Proxy                                        October 1999
      1. Introduction
        The IETF has come up with two architectures to support QoS in IP
        networks. IntServ (Integrated Services [RFC1633], [RFC2210]) is an
        architecture that provides the ability for applications to choose
        among multiple, controlled levels of delivery service for their data
        packets. It relies upon explicit signaling by applications to the
        network for the desired QoS. These applications typically know their
        traffic characteristics and have possibly strict latency
        requirements. Such applications require so called "tight QoS" or
        "quantitative QoS". RSVP is the protocol which can be used by
        applications to signal their QoS requirements to the network.
        Applications have to be modified to take advantage of the Integrated
        Services. The receivers control the QoS given to the data stream.
        DiffServ (Differentiated Services, [RFC2474], [RFC2475]) is another
        IETF architecture for implementing scalable service differentiation
        in the Internet. There is no explicit signaling protocol used in
        DiffServ. The network is logically divided into edge devices and core
        devices. The edge devices attempt to recognize data flows and assign
        QoS based on this. They also assign a DSCP (DiffServ Code Point) in
        the DS byte of the packets (the byte that used to be called the TOS
        byte). Core devices use the DSCP to assign a QoS to the microflows.
        Applications typically do not have to be modified to take advantage
        of Differentiated Services. Receivers do not control the QoS given to
        the data stream.
        The recognition of data flows and the assignment of an appropriate
        DSCP is a tricky task and often requires stateful inspection of flows
        and symmetrical routing paths. Moreover, application recognition is
        limited to the information present in the packet traversing the
        network and in most current network devices is further limited to
        what is in the IP/TCP/UDP headers. Application vendors desire to be
        able to assign QoS to their packets based on both information that
        may not be carried in the packet and information other than the
        IP/TCP/UDP header fields. For example, a SAP print transaction may
        require a different treatment than a SAP database update. Similarly,
        if the user of the application is the CTO of the company, the
        priority assigned to such packets maybe different from that assigned
        to packets of the application being used by some other person in the
        For this reason RSVP has been proposed also for mission critical
        applications (e.g. ERP) that require some form of prioritized
        service, but cannot readily specify their resource requirements. The
        ISSLL WG is discussing the specification of the Null Service Type as
        a way to use RSVP with a broader range of applications [NullServ].
        Gai, Dutt, Elfassy, Bernet                                  [Page 3]

      RSVP Receiver Proxy                                        October 1999
        Some of these applications have the requirement for the end-to-end
        message processing of RSVP. Others simply need to signal to the
        network their identity [Identity] and some additional policy
        information [Policy] related to the flows and obtaining from the
        network some decisions, e.g. the DSCP to be used [DCLASS].
        RSVP Receiver Proxy is a proposal that mainly addresses this second
        type of applications, i.e., applications that simply want to use RSVP
        as a signaling protocol toward the network. For them, the end-to-end
        nature of RSVP is not interesting and often is perceived as a
        disadvantage, since it is characterized by a higher latency.
        The RSVP Receiver Proxy:
        o  is an alternate way to process RSVP messages and policy information
           in the switch/routers;
        o  it does not require any change to the RSVP protocol;
        o  it does require an extension to the COPS for RSVP protocol [COPS-
        In general, "RSVP Proxy" should be symmetric, i.e., it may be useful
        to have RSVP Sender Proxy as well as RSVP Receiver Proxy. This
        document does not define RSVP Sender Proxy at this stage. If the
        document is accepted by the IETF community, the RSVP Sender Proxy can
        be added in the next version.
        This document defines RSVP Receiver Proxy in association with the
        Null Service Type, but nothing prevents using this feature also in
        association with other service types, e.g. the Controlled Load
        The following section uses an example in which the Receiver Proxy
        functionality is placed in the first hop switch/router. This is a
        possibility, but it is not a requirement. While designing a network
        the following trade-off should be considered:
        o  Proxying closer to the server reduces turn around time.
        o  Proxying further from the server enables additional downstream
           network elements to benefit from the information carried in the
           signaling messages, and to participate in the response.
        o  Proxying anywhere in the network enables the deployment of such
           applications in which only the server is required to signal, but
        Gai, Dutt, Elfassy, Bernet                                  [Page 4]

      RSVP Receiver Proxy                                        October 1999
           the client may remain unchanged.
        The COPS-RSVP Extension [COPS-RSVP-EXT] should enable the network
        administrator to decide how to make the tradeoffs described above.
      2. An overview of RSVP Receiver Proxy
        With RSVP Receiver Proxy a switch/router acts as a proxy for the
        receiver, e.g. when it receives an RSVP Path message, it generates an
        RSVP Resv message on behalf of the receiver.
        The generation of the Resv message is done under policy control, the
        switch/router may be programmed either to classify the packets
        marking them with an appropriate DSCP or to use the DCLASS object
        [DCLASS] to communicate the classification decision to the host.
        The adoption of RSVP Receiver Proxy do not change the basic model of
        RSVP, i.e.:
        o  the handling of data flows is unidirectional. If the application
           data is strictly unidirectional it is sufficient to use RSVP only
           in one direction. In the case of bidirectional data, running RSVP
           only in one direction provides a certain performance benefit, but
           to get the maximum performance benefit it is necessary to use RSVP
           in both directions.
        o  The application on the host assumes the host model of RSVP,
           including the extensions proposed in [DiffModel], [Policy],
           [Identity], [NullServ].
        o  The message format and the message types are the same of RSVP,
           including the DCLASS object previously proposed in [DCLASS] and the
           Null Service Type [NullServ].
        o  The switch/router acts as a COPS client [COPS] in communicating
           with the policy server, i.e. it uses RSVP client for COPS [COPS-
           RSVP]. Certain extensions to COPS for RSVP are needed [COPS-RSVP-
           EXT], see Section 4.
        o  The classification of traffic cannot be more granular than
           microflow (the so called five-tuple) or in the case of IPSEC the
           four-tuple that includes the Parameter Index, or SPI, in place of
           the UDP/TCP-like ports [RFC2207].
        o  There is no special support for subflows (a set of packets inside a
           microflow). Of course, an application may send different Path
        Gai, Dutt, Elfassy, Bernet                                  [Page 5]

      RSVP Receiver Proxy                                        October 1999
           messages for the same flow at different times, thus providing a
           support for subflows not overlapping in time.
      3. Detailed description of the message processing
        This sections details some of the message processing of a
        switch/router acting as RSVP Receiver Proxy. The description is
        mainly focused on the two fundamental messages in RSVP, i.e. the
        Path Message and the Resv message. Other messages are discussed in
        Section 4.4.
        Figure 1 depicts a simple network topology (two hosts H1 & H2 and
        intermediate routers, R1-R5) that will be used in the explanation.
                                Path Message ----->
                                <----- Resv Message
                          +-----+                  +-----+
                          | PS1 |                  | PS1 |
                          +-----+                  +-----+
                         /   |    \                /   |
                        /    |     \              /    |
                       /     |      \            /     |
        +----+   +----+   +----+   +----+   +----+   +----+   +----+
        | H1 |---| R1 |---| R2 |---| R3 |---| R4 |---| R5 |---| H2 |
        +----+   +----+   +----+   +----+   +----+   +----+   +----+
          H1 ----> R1 ----> R2 ----> R3 ----> R4 ----> R5 ----> H2  (Regular
                                                                 |   RSVP
                                                                 v   case)
          H1 <---- R1 <---- R2 <---- R3 <---- R4 <---- R5 ----> H2
          H1 ----> R1
                    |                       (RSVP Receiver Proxy)
          H1 <---- R1
        Hx: Host x
        Ry: Router y
        PSz: Policy Server z
        Figure 1: Possible Message Forwarding Behaviors in RSVP
        Gai, Dutt, Elfassy, Bernet                                  [Page 6]

      RSVP Receiver Proxy                                        October 1999
        Immediately below the network, the normal RSVP message processing is
        reported. The Path message goes hop-by-hop from H1 to H2. The Resv
        message uses the reverse path of the Path message and goes from H2 to
        H1. The interaction between the network devices and the policy
        servers is the one specified by COPS for RSVP ([COPS], [COPS-RSVP]).
        With RSVP Receiver Proxy the propagation of the RSVP Path message is
        terminated in the router acting as a proxy. Any router in the network
        may act as RSVP Receiver Proxy, but it is a good design guideline to
        place the proxy functionality as close as possible to the sender. In
        our case R1 acts as a proxy for H2 under the control of a policy
        For example, an application on H1 uses RSVP to signal parameters upon
        which to base the decision to assign the QoS for a microflow. The
        example assumes that the information needs to be used only by the
        edge network device and it is not required to propagate this further
        down the network
        A possible sequence of steps consists of:
        o  The application on H1 indicates to the RSVP subsystem that it is a
           sender and specifies its traffic characteristics. It may specify
           additional parameters.
        o  This causes the RSVP subsystem on H1 to start transmitting RSVP
           Path messages in accordance with normal RSVP/SBM rules.
        o  The first hop switch/router (R1) receives this message and it
           communicates with the policy server for a decision on how to treat
           the Path message. It copies all the relevant information contained
           in the Path message to the policy server.
        o  The policy server communicates a decision to R1 to not forward the
           Path message, but instead to originate and send a Resv message to
           H1. H1 data traffic gets assigned the right DSCP by the
           switch/router as per the policy communicated by the policy server.
           The Resv message may also specify to the host the DSCP and shaping
           information to be associated with the microflow using the DCLASS
           object [DCLASS].
        o  On receiving the Resv message, H1 may start marking correctly the
           data traffic accordingly to the DSCP received in the Resv message.
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      RSVP Receiver Proxy                                        October 1999
      4. The role of the policy server
        To implement both RSVP and RSVP Receiver Proxy the policy server
        needs to specify a set of decisions [COPS-RSVP-EXT] which is extended
        compared to COPS-RSVP [COPS-RSVP]. If the decision is to accept the
        Path message, the decision message must specify how the network
        device behaves with respect to each of the following:
        o  Forwarding of the Path message;
        o  Originating a RSVP Resv message;
        o  Processing and possibly Forwarding a RSVP Resv message.
        The decision may also possibly include the QoS specification to be
        associated with the flow identified in the Path message. This
        specification consists of a DSCP and possibly a TSPEC (as specified
        by RSVP [RFC2210]) for policing the traffic.
      4.1 Generation of the Resv message by the Receiver Proxy
        It maybe required that the network device originate a Resv message.
        This is a proxy Resv message in the sense that it is being generated
        by the network device and not by the actual receiver(s) identified in
        the RSVP Path message. The format of a Resv message is as follows
        (see [RFC2205] for details):
        <Resv Message> ::=     <Common Header> [ <INTEGRITY> ]
           [ <RESV_CONFIRM> ] [ <SCOPE> ] [ <POLICY_DATA>... ]
           <STYLE> <flow descriptor list>
        o  The network device puts its IP address and L2 address in the source
           IP and source mac-address fields. Since Resv messages follow Path
           messages, this would constitute a valid Resv message.
        o  The SESSION object can be copied from the Path message.
        o  The RSVP HOP object can be filled in with the IP address of the
           switch/router generating this Resv message.
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      RSVP Receiver Proxy                                        October 1999
        o  The TIME_VALUES object contains the refresh period. See below.
        o  The STYLE object is set to Wildcard Filter (WF) style indicating
           that the reservation is to be shared and that the sender is
           wildcarded. Associated with a WF style is a FLOWSPEC object which
           is encoded as specified in [RFC2210] or [NullServ].
        o  The SCOPE and RESV_CONFIRM objects need not be included in the Resv
        o  The POLICY_DATA objects will be as returned by the policy server.
        o  The Resv message may also contain the new DCLASS object is
           contained in the COPS decision message. The DCLASS object specifies
           the DSCP to be associated with the microflow for which the Path
           message was received.
        o  The Resv messages need to be originated and sent for each of the
           periodically-received Path messages.
      4.2 Communication With the Policy Server
        When a network device establishes the connection with the policy
        server, it sends a COPS Client-Open message for the RSVP client. It
        should indicate in this message whether the network device is capable
        of supporting only the base RSVP message processing or also the
        Receiver Proxy message processing. It can do this with in a
        capability list (that can accommodate also future extensions). To
        deal with existing clients, if the policy server does not receive a
        capability list, it should assume that it is communicating with a
        legacy RSVP client. The capability list can be included as part of
        the ClientSI object passed in the Client-Open message [COPS-RSVP-
        On receiving a RSVP Path message, the network device sends a COPS REQ
        message to the policy server. This message will be the standard REQ
        message sent on receiving a RSVP Path message.
        The DEC message returned by the policy server for this REQ message
        must contain the information needed to take the decisions listed in
        Section 4.
        The DEC message SHOULD also contain a list of DSCP [DCLASS].
        The DEC message may also contain bandwidth information to be
        associated with the microflow: communicating Shaping/limiting
        Gai, Dutt, Elfassy, Bernet                                  [Page 9]

      RSVP Receiver Proxy                                        October 1999
        parameters to the network is a powerful Policy Management tool for
        the PDP/LPDP both for Qualitative and Quantitative services. This
        topic needs further study.
        The network device must also be able to determine if a Path message
        is a refresh or a new one. It must communicate with the policy server
        only for new Path messages or for updated ones.
        In the absence of a policy server or if the connection to the policy
        server is not up, the operation of RSVP Receiver Proxy depends on
        policy configuration local to the network device. For example, the
        network device may have a local configuration that specifies:
        o  do not accept new flows;
        o  honor existing flows until they time-out.
      4.3 Enhancements To Existing Infrastructure
        o  COPS for RSVP will have to be enhanced to support the new format
           for RSVP REQ and DEC message as stated in [COPS-RSVP-EXT].
        o  When SBM is in use, it is possible that a device which does not
           support RSVP Receiver Proxy becomes the DSBM on the first-hop
           segment. This can be prevented by the network administrator by
           configuring the appropriate priority on the device with RSVP
           Receiver Proxy support.
      4.4 Processing of other RSVP messages
        This section details the processing of the protocol messages in RSVP
        other than Path and Resv. Only the differences in the processing from
        classical RSVP is specified.
        o  PathTear message is honored and is forwarded or not similar to a
           Path message. The policy server is not contacted on receiving a
           PathTear message. This is consistent with the existing behavior of
           COPS for RSVP[RSVP-COPS].
        o  PathErr messages are treated as in normal RSVP.
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      RSVP Receiver Proxy                                        October 1999
      5. RSVP With Null Service Type
        RSVP protocol can be represented as consisting of two parts: a
        message processing part and a resource allocation & resource
        enforcement part. The following are the minimal requirements for a
        network device to support RSVP Null Service Type:
        o  The network device MUST implement the message processing part of
           the RSVP protocol. This includes the ability to receive and
           interpret a raw IP packet or UDP-based RSVP packet.
        o  If the network device is a L2 device, it SHOULD implement SBM.
        o  The network device SHOULD know how to talk to a policy server using
           COPS. Specifically, the network device SHOULD be able to talk to
           COPS as a RSVP client using the extensions defined in [COPS-RSVP-
        o  The node SHOULD keep the RSVP state so that the following Path
           refresh won't cause a repetitive Path handling.
        o  The network device SHOULD be able to generate a Resv message
           periodically in a coherent way with the RSVP soft state
        o  In the absence of a connection to the policy server, this network
           device depends on policy configuration local to the network device
           (see Section 4.2).
      6. Security Considerations
        RSVP messages contain an INTEGRITY object which authenticates the
        originating node and is also used to verify the contents of the
        message. Moreover the RSVP message SHOULD contain an IDENTITY object
        that SHOULD be authenticated. If the policy server does not implement
        any security mechanisms, it SHOULD use a clear text version of the
        user identity.
      7. Intellectual Property Considerations
        The IETF is being notified of intellectual property rights claimed in
        regard to some or all of the specification contained in this
        document. For more information consult the online list of claimed
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      RSVP Receiver Proxy                                        October 1999
      8. References
        [COPS]       Boyle, J., Cohen, R., Durham, D., Herzog, S., Raja, R.,
                     Sastry, A., "The COPS (Common Open Policy Service)
                     Protocol", IETF <draft-ietf-rap-cops-07.txt>, August
        [RFC1633]    R. Braden, D. Clark, S. Shenker, "Integrated Services in
                     the Internet Architecture: an Overview," June 1994.
        [RFC2205]    Braden, R., Zhang, L., Berson, S., Herzog, S., and Jamin,
                     S., "Resource Reservation Protocol (RSVP) Version 1
                     Functional Specification", IETF RFC 2205, Proposed
                     Standard, September 1997.
        [RFC2210]    J. Wroclawski, "The Use of RSVP with IETF Integrated
                     Services," September 1997.
        [RFC2474]    K. Nichols, S. Blake, F. Baker, D. Black, "Definition of
                     the Differentiated Services Field (DS Field) in the IPv4
                     and IPv6 Headers," December 1998.
        [RFC2475]    S. Blake, D. Black, M. Carlson, E. Davies, Z. Wang, W.
                     Weiss, "An Architecture for Differentiated Service," RFC
                     2475, December 1998.
        [COPS-RSVP]  Jim Boyle, Ron Cohen, David Durham, Shai Herzog, Raju
                     Rajan, Arun Sastry, "COPS usage for RSVP," <draft-ietf-
                     rap-cops-rsvp-05.txt>, June 14, 1999
        [COPS-RSVP-EXT]   Nitsan Elfassy, Dinesh Dutt, "COPS Extensions for
                     RSVP Receiver Proxy Support"," <draft-nitsan-cops-rsvp-
                     proxy-00.txt>, October 1999.
        [Policy]     Shai Herzog, "RSVP Extensions for Policy Control,"
                     Internet Draft., < draft-ietf-rap-rsvp-ext-06.txt>, April
        [DiffModel]  Y. Bernet, A. Smith, S. Blake, "A Conceptual Model for
                     Diffserv Routers," Internet Draft, <draft-ietf-diffserv-
                     model-00.txt>, June 1999.
        [Identity]   Satyendra Yadav, Raj Yavatkar, Ramesh Pabbati, Peter
                     Ford, Tim Moore, Shai Herzog, "Identity Representation
                     for RSVP," Internet-Draft <draft-ietf-rap-rsvp-identity-
                     05.txt>, September 1999.
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      RSVP Receiver Proxy                                        October 1999
        [AggrRSVP]   Fred Baker, Carol Iturralde, Francois Le Faucheur, Bruce
                     Davie, "Aggregation of RSVP for IP4 and IP6
                     Reservations," <draft-ietf-issll-rsvp-aggr-00.txt>,
                     September 1999
        [DCLASS]     Bernet, Y., "Usage and Format of the DCLASS Object With
                     RSVP Signaling," <draft-ietf-issll-dclass-00.txt >,
                     August 1999.
        [NullServ]   Yoram Bernet, Andrew Smith, B. Davie, "Specification of
                     the Null Service Type," <draft-ietf-issll-nullservice-
                     00.txt>, September 1999
        [RSVPDIFF]   Bernet, R. Yavatkar, P. Ford, F. Baker, L. Zhang, M.
                     Speer, B. Braden, B. Davie, J. Wroclawski, E. Felstaine,
                     "Integrated Services Operation Over Diffserv Networks,"
                     <draft-ietf-issll-diffserv-rsvp-03.txt>, September 1999
        Gai, Dutt, Elfassy, Bernet                                  [Page 13]

      RSVP Receiver Proxy                                        October 1999
      9. Author Information
        Silvano Gai
        Cisco Systems, Inc.
        170 Tasman Dr.
        San Jose, CA 95134-1706
        Phone: (408) 527-2690
        email: sgai@cisco.com
        Dinesh Dutt
        Cisco Systems, Inc.
        170 Tasman Dr.
        San Jose, CA 95134-1706
        Phone: (408) 527-0955
        email: ddutt@cisco.com
        Nitsan Elfassy
        Cisco Systems, Inc.
        Cisco Systems, Inc.
        170 Tasman Dr.
        San Jose, CA 95134-1706
        Phone: +972 9 970 0066
        email: nitsan@cisco.com
        Bernet, Yoram
        One Microsoft Way,
        Redmond, WA 98052
        Phone: (425) 936-9568
        Email: yoramb@microsoft.com
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      RSVP Receiver Proxy                                        October 1999
      10. Full Copyright Statement
        Copyright (C) The Internet Society (1997).  All Rights Reserved.
        This document and translations of it may be copied and furnished to
        others, and derivative works that comment on or otherwise explain it
        or assist in its implementation may be prepared, copied, published
        and distributed, in whole or in part, without restriction of any
        kind, provided that the above copyright notice and this paragraph are
        included on all such copies and derivative works.  However, this
        document itself may not be modified in any way, such as by removing
        the copyright notice or references to the Internet Society or other
        Internet organizations, except as needed for the purpose of
        developing Internet standards in which case the procedures for
        copyrights defined in the Internet Standards process must be
        followed, or as required to translate it into languages other than
        The limited permissions granted above are perpetual and will not be
        revoked by the Internet Society or its successors or assigns.
        This document and the information contained herein is provided on an
        Gai, Dutt, Elfassy, Bernet                                  [Page 15]

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