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RSVP(7)


NAME

  RSVP, rsvp - Resource ReSerVation Protocol general information


DESCRIPTION

  Resource ReSerVation Protocol, also known as RSVP, is an Internet protocol
  that enables Internet applications to request enhanced quality-of-service
  (QoS). The Internet application uses the RSVP Application Programming
  Interface (RAPI) routines to make the QoS request.  The RSVP control
  program, rsvpd, uses the RSVP protocol to propagate the QoS request through
  routers along the path or paths for the data flow.  Each router accepts or
  rejects the request depending on its available resources.  If the request
  fails, rsvpd informs the application using RAPI.

  RSVP Model

  RSVP performs the signaling necessary to make a resource reservation for a
  simplex data flow sent to a unicast or multicast destination address.
  Although RSVP distinguishes senders from receivers, an application can act
  as both.

  RSVP assigns a QoS to a specific multipoint-to-multipoint data flow called
  a session.  A session is defined by a transport protocol, IP destination
  address, and a destination port.  In order to receive data packets for a
  particular multicast session, the host must join the IP multicast group by
  using the setsockopt call with the IP_ADD_MEMBERSHIP option (IPv4) or
  IPV6_JOIN_GROUP option (IPv6).

  A sender, or data source, is defined by an IP source address and a source
  port. A session can have multiple senders and, if the destination is a
  multicast address, multiple receivers.  TCP/UDP port numbers are used by
  RSVP for defining sessions and senders.

  Under RSVP, data receivers make the QoS requests.  A QoS request contains a
  flowspec and a filter spec.  The flowspec includes an Rspec, which defines
  the desired QoS and is used to control the packet scheduling mechanism in
  the router or host, and a Tspec, which defines the traffic that the
  receiver expects.  The filter spec controls packet classification to
  determine which sender's data packets receive the corresponding QoS.

  The reservation style reservation parameter controls how reservations from
  different receivers are shared in the Internet.  See RFC 2205 for
  information on reservation styles.

  RSVP API

  The RSVP API (RAPI) consists of the following routines:

  rapi_session
      An application calls this routine to define an API session for sending
      or receiving, or both, a single simplex data flow.

  rapi_sender
      An application calls this routine to register as a data sender.

  rapi_reserve
      An application calls this routine to make a QoS reservation as a data
      receiver.

  rapi_release
      An application calls this routine to close an API session and delete
      all resource reservations.

  rapi_getfd
      An application calls this routine to obtain the file descriptor
      associated with the UNIX socket connected to rsvpd.

  rapi_dispatch
      An application calls this routine when a read event is signaled on the
      file descriptor that was obtained by a successful call to rapi_getfd.

  rapi_version
      An application calls this routine to obtain the version of RAPI on the
      system.

  rapi_event_rtn_t
      The API calls this routine to invoke a procedure whose address was
      specified in a call to rapi_session.

  A single API session, defined by a single call to rapi_session, can have
  only one sender at a time.  More than one API session can be established
  for the same RSVP session.  For example, if an application sends multiple
  UDP data flows, distinguished by source port, the application calls
  rapi_session and rapi_sender separately for each of the flows.

  The rapi_session routine allows the application to specify an upcall
  (callback) routine that is invoked to signal RSVP state change and error
  events.  See rapi_event_rtn_t(3) for a description of the upcalls.

  Upcall routines are invoked indirectly and synchronously by the application
  in the following manner:

    ·  Application issues a call to the rapi_getfd() routine to learn the
       file descriptor of the UNIX socket used by the API.

    ·  The application detects read events on this file descriptor, either
       passing it directly in a select call or passing it to the notifier of
       another library.

    ·  When a read event on the file descriptor is signaled, the application
       calls rapi_dispatch.  This call makes the API execute the upcall
       routine, if defined.

  The rapi_sender and rapi_reserve calls can be repeated with different
  parameters at different times to modify the state at any time, or can be
  issued with null parameters to retract the correcponding registration.

  RAPI Objects

  Every RAPI object consists of two words: the total length of the object (in
  bytes) and the object type.  An empty object consists of a header with type
  zero and a length of 8 bytes.

  The RAPI defines the following RAPI objects and their respective formats:

    ·  Flowspec

	 -- RAPI_FLOWSTYPE_Simplified

	    A simple list of parameters needed for either Guaranteed or
	    Controlled Load service, using the service type QOS_GUARANTEED or
	    QOS_CNTR_LOAD, respectively.  The RAPI client library routines
	    map this format to and from an appropriate Integrated Services
	    data structure.

	 -- RAPI_FLOWSTYPE_Intserv

	    A fully formatted Integrated Services flowspec data structure.

       In an upcall, a flowspec is delivered in simplified format by default.
       However, if the RAPI_USE_INTSERV flag is set in the rapi_session()
       call, the IntServ format is used in upcalls.

    ·  Filter spec and sender template

	 -- RAPI_FILTERFORM_BASE

	    A socket address structure that defines the IP address and port.

	 -- RAPI_FILTERFORM_GPI

	    An address structure that defines the IP address and 32-bit
	    Gereralized Port Identifier.  This is recommended for all IP
	    Security (IPSEC) applications.

    ·  sender Tspec

	 -- RAPI_TSPECTYPE_Simplified

	    A simple list of parameters with the service type QOS_TSPEC.  The
	    RAPI client library routines map this format to and from an
	    appropriate Integrated Services data structure.

	 -- RAPI_TSPECTYPE_Intserv A fully formatted Integrated Services
	    Tspec data structure.

       In an upcall, a sender Tspec is delivered in simplified format by
       default.	 However, if the RAPI_USE_INTSERV flag is set in the
       rapi_session() call, the IntServ format is used in upcalls.

    ·  Adspec

	 -- RAPI_ADSTYPE_Simplified

	    A simple list of Adspec parameters for all possible services.
	    The RAPI client library routines map this format to and from an
	    appropriate Integrated Services data structure.

	 -- RAPI_ADSTYPE_Intserv A fully formatted Integrated Services Tspec
	    data structure.

       In an upcall, an Adspec is delivered in simplified format by default.
       However, if the RAPI_USE_INTSERV flag is set in the rapi_session()
       call, the IntServ format is used in upcalls.

  See <rapi_lib.h> and <rsvp_intserv.h> for additional information on RAPI
  object formats.  See the Resource ReSerVation Protocol API (RAPI) technical
  standard by The Open Group for information on Integrated Services data
  structures.


SEE ALSO

  Commands: iftcntl(8), rsvpd(8), rsvpstat(8)

  Routines: rapi_dispatch(3), rapi_event_rtn_t(3), rapi_getfd(3),
  rapi_release(3), rapi_reserve(3), rapi_sender(3), rapi_session(3),
  rapi_version(3)

  RFC 2205, Resource ReSerVation Protocol (RSVP) Version 1 Functional
  Specification

  RFC 2206, RSVP Management Information Base using SMIv2

  RFC 2207, RSVP Extensions for IPSEC Data Flows

  RFC 2208, Resource ReSerVation Protocol (RSVP) Version 1 Applicability
  Statement Some Guidelines on Deployment

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

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