RFC 2771 (rfc2771) - Page 2 of 11

An Abstract API for Multicast Address Allocation

RFC 2771     Abstract API for Multicast Address Allocation February 2000


   might be co-located (along with one or more applications) on an end
   node, in which case some other, internal, mechanism might be used to
   access the server.  In either case, however, the abstract service
   interface (and, presumably, any specific APIs) would remain the same.

   The remainder of this document describes the abstract interface.

   Note that this interface is intended only for the allocation of
   dynamic multicast addresses, as used by the traditional multicast
   service model [2].  Future multicast service models might allocate or
   assign multicast addresses in other ways, but this is outside the
   scope of this document.

2. Abstract Data Types

   The interface described below uses the following abstract data types:

   -  AddressFamily: e.g., IPv4 or IPv6

   -  MulticastAddress: An actual multicast address (i.e., that could
      subsequently be used as the destination of a datagram)

   -  MulticastAddressSet: A set of "MulticastAddress"es

   -  LanguageTag: The code for a (human) language, as defined in [4]

   -  Scope: An "administrative scope" [3] from which multicast
             addresses are to be allocated.  Each scope is a
             "MulticastAddressSet", with an associated set of
             (character-string) names - indexed by "LanguageTag".  (Each
             language tag has at most one corresponding name, per
             scope.)  For each scope, a (language tag, name) pair may be
             defined to be the 'default' name for this scope. (See the
             section "Querying the name of a scope" below.)

             (An implementation of this abstract data type might also
             include other information, such as a default TTL for the
             scope.)

   -  Time: An (absolute) event time.  This is used for specifying the
            "lifetime" of multicast addresses: the period of time during
            which allocated multicast addresses are guaranteed to be
            available.  (It is also used to specify the desired start
            time for an "advance allocation".)







Finlayson                    Informational