rfc2207.txt

<VC++网络游戏建摸与实现>源代码

Network Working Group                                     L. Berger
Request for Comments: 2207                             FORE Systems
Category: Standards Track                               T. O'Malley
                                                                BBN
                                                     September 1997


                  RSVP Extensions for IPSEC Data Flows


Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.



Abstract

   This document presents extensions to Version 1 of RSVP.  These
   extensions permit support of individual data flows using RFC 1826, IP
   Authentication Header (AH) or RFC 1827, IP Encapsulating Security
   Payload (ESP).  RSVP Version 1 as currently specified can support the
   IPSEC protocols, but only on a per address, per protocol basis not on
   a per flow basis.  The presented extensions can be used with both
   IPv4 and IPv6.






















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Table of Contents

   1   Introduction . . . . . . . . . . . . . . . . . . . . . . . 2
   2   Overview of Extensions . . . . . . . . . . . . . . . . . . 3
   3   Object Definition. . . . . . . . . . . . . . . . . . . . . 4
       3.1  SESSION Class . . . . . . . . . . . . . . . . . . . . 5
       3.2  FILTER_SPEC Class . . . . . . . . . . . . . . . . . . 5
       3.3  SENDER_TEMPLATE Class . . . . . . . . . . . . . . . . 6
   4   Processing Rules . . . . . . . . . . . . . . . . . . . . . 6
       4.1  Required Changes. . . . . . . . . . . . . . . . . . . 6
       4.2  Merging Flowspecs . . . . . . . . . . . . . . . . . . 7
       4.2.1  FF and SE Styles. . . . . . . . . . . . . . . . . . 7
       4.2.2  WF Styles . . . . . . . . . . . . . . . . . . . . . 8
   5   IANA Considerations. . . . . . . . . . . . . . . . . . . . 8
   6   Security Considerations. . . . . . . . . . . . . . . . . . 8
   7   References . . . . . . . . . . . . . . . . . . . . . . . .10
   8   Acknowledgments . . . . . . . . . . . .  . . . . . . . . .10
   9   Authors' Addresses . . . . . . . . . . . . . . . . . . . .10
   A   Options Considered . . . . . . . . . . . . . . . . . . . .11
       A.1  UDP Encapsulation . . . . . . . . . . . . . . . . . .11
       A.2  FlowID Header Encapsulation . . . . . . . . . . . . .12
       A.3  IPSEC Protocol Modification . . . . . . . . . . . . .12
       A.4  AH Transparency . . . . . . . . . . . . . . . . . . .13

1   Introduction

   Recently published Standards Track RFCs specify protocol mechanisms
   to provide IP level security.  These IP Security, or IPSEC, protocols
   support packet level authentication, [RFC 1826], and integrity and
   confidentiality [RFC 1827].  A number of interoperable
   implementations already exist and several vendors have announced
   commercial products that will use these mechanisms.

   The IPSEC protocols provide service by adding a new header between a
   packet's IP header and the transport (e.g. UDP) protocol header.  The
   two security headers are the Authentication Header (AH), for
   authentication, and the Encapsulating Security Payload (ESP), for
   integrity and confidentiality.

   RSVP is being developed as a resource reservation (dynamic QoS setup)
   protocol.  RSVP as currently specified [RFC 2205] is tailored towards
   IP packets carrying protocols that have TCP or UDP-like ports.
   Protocols that do not have such UDP/TCP-like ports, such as the IPSEC
   protocols, can be supported, but only with limitations.
   Specifically, for flows of IPSEC data packets, flow definition can
   only be done on per IP address, per protocol basis.





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   This memo proposes extensions to RSVP so that data flows containing
   IPSEC protocols can be controlled at a granularity similar to what is
   already specified for UDP and TCP.  The proposed extensions can be
   used with both IPv4 and IPv6.  Section 2 of this memo will provide an
   overview of extensions.  Section 3 contains a description of extended
   protocol mechanisms.  Section 4 presents extended protocol processing
   rules.  Section 5 defines the additional RSVP data objects.

2   Overview of Extensions

   The basic notion is to extend RSVP to use the IPSEC Security
   Parameter Index, or SPI, in place of the UDP/TCP-like ports.  This
   will require a new FILTER_SPEC object, which will contain the IPSEC
   SPI, and a new SESSION object.

   While SPIs are allocated based on destination address, they will
   typically be associated with a particular sender.  As a result, two
   senders to the same unicast destination will usually have different
   SPIs.  In order to support the control of multiple independent flows
   between source and destination IP addresses, the SPI will be included
   as part of the FILTER_SPEC.  When using WF, however, all flows to the
   same IP destination address using the same IP protocol ID will share
   the same reservation.  (This limitation exists because the IPSEC
   transport headers do not contain a destination demultiplexing value
   like the UDP/TCP destination port.)

   Although the RESV message format will not change, RESV processing
   will require modification.  Processing of the new IPSEC FILTER_SPEC
   will depend on the use of the new SESSION object and on the protocol
   ID contained in the session definition.  When the new FILTER_SPEC
   object is used, the complete four bytes of the SPI will need to be
   extracted from the FILTER_SPEC for use by the packet classifier.  The
   location of the SPI in the transport header of the IPSEC packets is
   dependent on the protocol ID field.

   The extension will also require a change to PATH processing,
   specifically in the usage of the port field in a session definition.
   An RSVP session is defined by the triple: (DestAddress, protocol ID,
   DstPort).  [RFC 2205] includes the definition of one type of SESSION
   object, it contains UDP/TCP destination ports, specifically "a 16-bit
   quantity carried at the octet offset +2 in the transport header" or
   zero for protocols that lack such a field.  The IPSEC protocols do









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   not contain such a field, but there remains a requirement for
   demultiplexing sessions beyond the IP destination address.  In order
   to satisfy this requirement, a virtual destination port, or vDstPort,
   is introduced.  The vDstPort value will be carried in the new SESSION
   object but not in the IPSEC transport header.  The vDstPort allows
   for the differentiation of multiple IPSEC sessions destined to the
   same IP address.  See Section 5 for a discussion of vDstPort ranges.

   In PATH messages, the SENDER_TEMPLATE for IPSEC flows will have the
   same format as the modified FILTER_SPEC.  But, a new SESSION object
   will be used to unambiguously distinguish the use of a virtual
   destination port.

   Traffic will be mapped (classified) to reservations based on SPIs in
   FILTER_SPECs.  This, of course, means that when WF is used all flows
   to the same IP destination address and with the same IP protocol ID
   will share the same reservation.

   The advantages to the described approach are that no changes to
   RFC1826 and 1827 are required and that there is no additional per
   data packet overhead.  Appendix A contains a discussion of the
   advantages of this approach compared to several other alternatives.
   This approach does not take advantage of the IPv6 Flow Label field,
   so greater efficiency may be possible for IPv6 flows.  The details of
   IPv6 Flow Label usage is left for the future.

3   Object Definition

   The FILTER_SPEC and SENDER_TEMPLATE used with IPSEC protocols will
   contain a four byte field that will be used to carry the SPI.  Rather
   than label the modified field with an IPSEC specific label, SPI, the
   label "Generalized Port Identifier", or GPI, will be so that these
   object may be reused for non-IPSEC uses in the future.  The name for
   these objects are the IPv4/GPI FILTER_SPEC, IPv6/GPI FILTER_SPEC,
   IPv4/GPI SENDER_TEMPLATE, and IPv6/GPI SENDER_TEMPLATE.  Similarly,
   the new SESSION objects will be the IPv4/GPI SESSION and the IPv6/GPI
   SESSION.  When referring to the new objects, IP version will not be
   included unless a specific distinction between IPv4 and IPv6 is being
   made.












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3.1  SESSION Class


        SESSION Class = 1.

        o    IPv4/GPI SESSION object: Class = 1, C-Type = 3

        +-------------+-------------+-------------+-------------+
        |               IPv4 DestAddress (4 bytes)              |
        +-------------+-------------+-------------+-------------+
        | Protocol ID |     Flags   |         vDstPort          |
        +-------------+-------------+-------------+-------------+


        o    IPv6/GPI SESSION object:  Class = 1, C-Type = 4

        +-------------+-------------+-------------+-------------+
        |                                                       |
        +                                                       +
        |                                                       |
        +               IPv6 DestAddress (16 bytes)             +
        |                                                       |
        +                                                       +
        |                                                       |
        +-------------+-------------+-------------+-------------+
        | Protocol ID |     Flags   |         vDstPort          |
        +-------------+-------------+-------------+-------------+

3.2  FILTER_SPEC Class

        FILTER_SPEC class = 10.

        o    IPv4/GPI FILTER_SPEC object: Class = 10, C-Type = 4

        +-------------+-------------+-------------+-------------+
        |               IPv4 SrcAddress (4 bytes)               |
        +-------------+-------------+-------------+-------------+
        |            Generalized Port Identifier (GPI)          |
        +-------------+-------------+-------------+-------------+












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        o    IPv6/GPI FILTER_SPEC object: Class = 10, C-Type = 5

        +-------------+-------------+-------------+-------------+
        |                                                       |
        +                                                       +
        |                                                       |
        +               IPv6 SrcAddress (16 bytes)              +
        |                                                       |
        +                                                       +
        |                                                       |
        +-------------+-------------+-------------+-------------+
        |            Generalized Port Identifier (GPI)          |
        +-------------+-------------+-------------+-------------+

3.3  SENDER_TEMPLATE Class

        SENDER_TEMPLATE class = 11.

        o    IPv4/GPI SENDER_TEMPLATE object: Class = 11, C-Type = 4

                 Definition same as IPv4/GPI FILTER_SPEC object.

        o    IPv6/GPI SENDER_TEMPLATE object: Class = 11, C-Type = 5

                 Definition same as IPv6/GPI FILTER_SPEC object.

4   Processing Rules

   This section presents additions to the Processing Rules presented in
   [RFC 2209].  These additions are required in order to properly
   process the GPI SESSION and FILTER_SPEC objects.  Values for
   referenced error codes can be found in [RFC 2205].  As in with the
   other RSVP documents, values for internally reported (API) errors are
   not defined.

4.1  Required Changes

   Both RESV and PATH processing will need to be changed to support the
   new objects.  The changes ensure consistency and extend port
   processing.

   The following PATH message processing changes are required:

     o  When a session is defined using the GPI SESSION object, only
        the GPI SENDER_TEMPLATE may be used.  When this condition is
        violated, end-stations should report a "Conflicting C-Type" API
        error to the application.




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     o  For PATH messages that contain the GPI SESSION object,
        end-stations must verify that the protocol ID corresponds to a
        protocol known to use the GPI SESSION object.  Values 51 (AH)
        or 50 (ESP) must be supported by implementations supporting
        the described IPSEC extensions.  If an unknown protocol ID is
        used, then the API should report an "API Error" to the
        application.

     o  For such messages, the vDstPort value should be recorded.
        The vDstPort value forms part of the recorded state and is used
        to match Resv messages, but it is not passed to traffic control.
        Non-zero values of vDstPort are required.  This requirement
        ensures that a non-GPI SESSION object will never merge with a
        GPI SESSION object.  Violation of this condition causes an
        "Invalid Destination Port" API error.

     The changes to RESV message processing are:

     o  When a RESV message contains a GPI FILTER_SPEC, the session
        must be defined using the GPI SESSION object. Otherwise, this is
        a message formatting error.

     o  The GPI contained in the FILTER_SPEC must match the GPI
        contained in the SENDER_TEMPLATE.  Otherwise, a "No sender
        information for this Resv message" error  is generated.

     o  When the GPI FILTER_SPEC is used, each node must create
        a data classifier for the flow described by the quadruple:
        (DestAddress, protocol ID, SrcAddress, GPI). The data classifier
        will need to look for the four byte GPI at transport header
        offset +4 for AH, and at transport header offset +0 for ESP.

4.2  Merging Flowspecs

   When using this extension for IPSEC data flows, RSVP sessions are
   defined by the triple: (DestAddress, protocol Id, vDstPort).
   Similarly, a sender is defined by the tuple: (SrcAddress, GPI), where
   the GPI field will be a four byte representation of a generalized
   source port.  These extensions have some ramifications depending upon
   the reservation style.

4.2.1  FF and SE Styles

   In the FF and SE Styles, the FILTER_SPEC object contains the
   (SrcAddress, GPI) pair.  This allows the receiver to uniquely
   identify senders based on both elements of the pair.  When merging
   explicit sender descriptors, the senders may only be considered
   identical when both elements are identical.



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