RFC 2383 (rfc2383) - Page 2 of 50

ST2+ over ATM Protocol Specification - UNI 3

RFC 2383                     ST2+ over ATM                   August 1998


   Therefore, in this document, ATM is only a subnet technology for the
   ST2+ stream.  This specification is designed to enable resource-
   reservation communications across ATM and non-ATM networks.

1.2 Features of ST2+ over ATM Protocol

   o Enables resource-reservation communications across ATM and non-ATM
     networks.

     ATM native API supports resource-reservation communications only
     within an ATM network; it cannot support interworking with non-ATM
     networks. This is because

     - ATM native API cannot connect terminals without an ATM interface.

     - ATM native API does not support IP addressing and SAP (port)
       addressing systems.

   o Extends UNI 3.1/4.0 signaling functions.

     ST2+ SCMP supports MTU-size negotiation at all hops in an ST2+
     tree-structure stream. UNI 3.1/4.0 supports only max CPCS_SDU
     (i.e., MTU) negotiation with the called party of a point-to-point
     call or with the first leaf of a point-to-multipoint call.

   o Reduces UNI 4.0 LIJ signaling limitations.

     The ST2+ over ATM protocol supports UNI 4.0 LIJ Call Identifier
     notification from the root to the leaf by using an ST2+ SCMP
     extension.  LIJ Call Identifier discovery at the leaf is one of the
     major unsolved problems of UNI 4.0, and the ST2+ over ATM protocol
     provides a solution.

     Note: The UNI 3.1 version of the ST2+ over ATM protocol does not
     support the above feature. It will be supported by the UNI 3.1/4.0
     version.

1.3 Goals and Non-goals of ST2+ over ATM Protocol

   The ST2+ over ATM protocol is designed to achieve the following
   goals.

   o Specify protocol interaction between ST2+ [4] and ATM on the ATM
     Forum Private UNI 3.1/4.0 (Sb point) [10, 11].

     Note: The UNI 3.1 version of the ST2+ over ATM protocol does not
     support UNI 4.0. It will be supported by the UNI 3.1/4.0 version.




Suzuki                       Informational