Resource ReSerVation Protocol (RSVP) -- Version 1 Message Processing Rules
RFC 2209

Document Type RFC - Informational (September 1997; Errata)
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Network Working Group                                          R. Braden
Request For Comments: 2209                                           ISI
Category: Informational                                         L. Zhang
                                                          September 1997

                Resource ReSerVation Protocol (RSVP) --
                   Version 1 Message Processing Rules

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.


   This memo contains an algorithmic description of the rules used by an
   RSVP implementation for processing messages.  It is intended to
   clarify the version 1 RSVP protocol specification.

   This memo provides a generic description of the rules for the
   operation of Version 1 of RSVP [RFC 2205].  It is intended to outline
   a set of algorithms that will accomplish the needed function,
   omitting many details.


   This memo assumes the generic interface calls defined in [RFC 2005]
   and the following data structures.  An actual implementation may use
   additional or different data structures and interfaces.  The data
   structure fields that are shown are required unless they are
   explicitly labelled as optional.

   o    PSB -- Path State Block

        Each PSB holds path state for a particular (session, sender)
        pair, defined by SESSION and SENDER_TEMPLATE objects,
        respectively, received in a PATH message.

Braden & Zhang               Informational                      [Page 1]
RFC 2209                RSVP-Message Processing           September 1997

        PSB contents include the following values from a PATH message:

        -    Session

        -    Sender_Template

        -    Sender_Tspec

        -    The previous hop IP address and the Logical Interface
             Handle (LIH) from a PHOP object

        -    The remaining IP TTL

        -    POLICY_DATA and/or ADSPEC objects (optional)

        -    Non_RSVP flag

        -    E_Police flag

        -    Local_Only flag

        In addition, the PSB contains the following information provided
        by routing: OutInterface_list, which is the list of outgoing
        interfaces for this (sender, destination), and IncInterface,
        which is the expected incoming interface.  For a unicast
        destination, OutInterface_list contains one entry and
        IncInterface is undefined.

        Note that there may be more than one PSB for the same (session,
        sender) pair but different incoming interfaces.  At most one of
        these, which will have the Local_Only flag off, will be the PSB
        used for forwarding PATH messages downstream; we will refer to
        it as the "forwarding PSB" in the following.  The other PSB's
        will have the Local_Only flag on and an empty
        OutInterface_list.h The Local_Only flag is needed to correctly
        match PSB's against RSB's, by the rules of [RFC 2205].

   o    RSB -- Reservation State Block

        Each RSB holds a reservation request that arrived in a
        particular RESV message, corresponding to the triple:  (session,
        next hop, Filter_spec_list).  Here "Filter_spec_list" may be a
        list of FILTER_SPECs (for SE style), a single FILTER_SPEC (FF
        style), or empty (WF style).  We define the virtual object type
        "FILTER_SPEC*" for such a data structure.

Braden & Zhang               Informational                      [Page 2]
RFC 2209                RSVP-Message Processing           September 1997

        RSB contents include:

        -    Session specification

        -    Next hop IP address

        -    Filter_spec_list

        -    The outgoing (logical) interface OI on which the
             reservation is to be made or has been made.

        -    Style

        -    Flowspec

        -    A SCOPE object (optional, depending upon style)

        -    RESV_CONFIRM object that was received (optional)

   o    TCSB -- Traffic Control State Block

        Each TCSB holds the reservation specification that has been
        handed to traffic control for a specific outgoing interface.  In
        general, TCSB information is derived from RSB's for the same
        outgoing interface.  Each TCSB defines a single reservation for
        a particular triple: (session, OI, Filter_spec_list).   TCSB
        contents include:

        -    Session

        -    OI (Outgoing Interface)

        -    Filter_spec_list

        -    TC_Flowspec, the effective flowspec, i.e., the LUB over the
             corresponding FLOWSPEC values from matching RSB's.
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