RFC 2353 (rfc2353) - Page 3 of 49

APPN/HPR in IP Networks APPN Implementers' Workshop Closed Pages Document

RFC 2353                APPN/HPR in IP Networks                 May 1998


1.1  Requirements

   The following are the requirements for the architecture specified in
   this memo:

   1.  Facilitate APPN product interoperation in IP networks by
       documenting agreements such as the choice of the logical link
       control (LLC).

   2.  Reduce system definition (e.g., by extending the connection
       network model to IP networks) -- Connection network support is an
       optional function.

   3.  Use class of service (COS) to retain existing path selection and
       transmission priority services in IP networks; extend
       transmission priority function to include IP networks.

   4.  Allow customers the flexibility to design their networks for low
       cost and high performance.

   5.  Use HPR functions to improve both availability and scalability
       over existing integration techniques such as Data Link Switching
       (DLSw) which is specified in RFC 1795 [4] and RFC 2166 [5].

2.0  IP as a Data Link Control (DLC) for HPR

   This memo specifies the use of IP and UDP as a new DLC that can be
   supported by APPN nodes with the three HPR option sets:  HPR (option
   set 1400), Rapid Transport Protocol (RTP) (option set 1401), and
   Control Flows over RTP (option set 1402).  Logical Data Link Control
   (LDLC) Support (option set 2006) is also a prerequisite.

   RTP is a connection-oriented, full-duplex protocol designed to
   transport data in high-speed networks.  HPR uses RTP connections to
   transport SNA session traffic.  RTP provides reliability (i.e., error
   recovery via selective retransmission), in-order delivery (i.e., a
   first-in-first-out [FIFO] service provided by resequencing data that
   arrives out of order), and adaptive rate-based (ARB) flow/congestion
   control. Because RTP provides these functions on an end-to-end basis,
   it eliminates the need for these functions on the link level along
   the path of the connection.  The result is improved overall
   performance for HPR.  For a more complete description of RTP, see
   Appendix F of [2].

   This new DLC (referred to as the native IP DLC) allows customers to
   take advantage of APPN/HPR functions such as class of service (COS)
   and ARB flow/congestion control in the IP environment.  HPR links
   established over the native IP DLC are referred to as HPR/IP links.



Dudley                       Informational