





Network Working Group                                           M. Rose
Request for Comments: 1418                 Dover Beach Consulting, Inc.
Obsoletes: 1161, 1283                                        March 1993


                             SNMP over OSI

Status of this Memo

   This RFC specifies an IAB standards track protocol for the Internet
   community, and requests discussion and suggestions for improvements.
   Please refer to the current edition of the "IAB Official Protocol
   Standards" for the standardization state and status of this protocol.
   Distribution of this memo is unlimited.

Table of Contents

   1. Background .................................................    1
   2. Mapping onto the CLTS ......................................    2
   2.1 Well-known Addresses ......................................    2
   2.2 Traps .....................................................    2
   2.3 Maximum Message Size ......................................    3
   3. Acknowledgements ...........................................    3
   4. References .................................................    3
   5. Security Considerations ....................................    4
   6. Author's Address ...........................................    4

1.  Background

   The Simple Network Management Protocol (SNMP) as defined in [1] is
   now used as an integral part of the network management framework for
   TCP/IP-based internets.  Together with its companions standards,
   which define the Structure of Management Information (SMI) [2,3], and
   the Management Information Base (MIB) [4], the SNMP has received
   widespread deployment in many operational networks running the
   Internet suite of protocols.

   It should not be surprising that many of these sites might acquire
   OSI capabilities and may wish to leverage their investment in SNMP
   technology towards managing those OSI components.  This memo
   addresses these concerns by defining a framework for running the SNMP
   in an environment which supports the OSI connectionless-mode
   transport service.

   However, as noted in [5], the preferred mapping for SNMP is onto the
   UDP [6].  This specification is intended for use in environments
   where UDP transport is not available.  No aspect of this
   specification should be construed as a suggestion that, in a



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RFC 1418                     SNMP over OSI                    March 1993


   heterogeneous transport environment, a managed agent should support
   more than one mapping.

2.  Mapping onto the CLTS

   Mapping the SNMP onto the CLTS [7,8] is straight-forward.  The
   elements of procedure are identical to that of using the UDP.  Note
   that the CLTS and the service offered by the UDP both transmit
   packets of information which contain full addressing information.
   Thus, mapping the SNMP onto the CLTS, a "transport address" in the
   context of [1], is simply a transport-selector and network address.

   It should be noted that the mapping of SNMP onto a connectionless-
   mode transport service is wholly consistent with SNMP's architectural
   principles, as described in [1,5].  However, the CLTS itself can be
   realized using either a connectionless-mode or a connection-oriented
   network service.  The mapping described in this mapping allows for
   either realization.  (When both network services are available, the
   CLNS should be used as the basis of realization.)

2.1.  Well-known Addresses

   Unlike the Internet suite of protocols, OSI does not use well-known
   ports.  Rather,
    demultiplexing occurs on the basis of "selectors", opaque strings of
   octets which have local significance.  In order to foster
   interoperable implementations of the SNMP over the CLTS, it is
   necessary define four selectors for this purpose.

   When the CLTS is used to provide the transport backing for the SNMP,
   and the CLTS uses a connectionless-mode network service, then
   transport selector used shall be "snmp-l" which consists of six ASCII
   characters; and, SNMP traps are, by convention, sent to an SNMP
   manager listening on the transport selector "snmpt-l" which consists
   of seven ASCII characters.

   When the CLTS is used to provide the transport backing for the SNMP,
   and the CLTS uses a connection-oriented network service, then
   transport selector used shall be "snmp-o" which consists of six ASCII
   characters; and, SNMP traps are, by convention, sent to an SNMP
   manager listening on the transport selector "snmpt-o" which consists
   of seven ASCII characters.

2.2.  Traps

   When SNMP traps are sent over the CLTS, the agent-addr field in the
   Trap-PDU contains the IP-address "0.0.0.0" An SNMP manager may
   ascertain the source of the trap based on information provided by the



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   transport service (i.e., from the T-UNIT-DATA.INDICATION primitive).

2.3.  Maximum Message Size

   An entity implementing SNMP over OSI must be prepared to accept
   messages whose size is at least 484 octets.  Implementation of larger
   values is encouraged whenever possible.

3.  Acknowledgements

   This specification was derived from RFC 1283, based on discussions in
   the IETF's "SNMP in a Multi-Protocol Internet" working group.

4.  References

   [1] Case, J., Fedor, M., Schoffstall, M., and J. Davin, "Simple
       Network Management Protocol", STD 15, RFC 1157, SNMP Research,
       Performance Systems International, Performance Systems
       International, MIT Laboratory for Computer Science, May 1990.

   [2] Rose M., and K. McCloghrie, "Structure and Identification of
       Management Information for TCP/IP-based internets", STD 16, RFC
       1155, Performance Systems International, Hughes LAN Systems, May
       1990.

   [3] Rose, M., and K. McCloghrie, Editors, "Concise MIB Definitions",
       STD 16, RFC 1212, Performance Systems International, Hughes LAN
       Systems, March 1991.

   [4] Rose M., and K. McCloghrie, Editors, "Management Information Base
       for Network Management of TCP/IP-based Internets", STD 17, RFC
       1213, Hughes LAN Systems, Inc., Performance Systems
       International, March 1991.

   [5] Kastenholz, F., "SNMP Communications Services", RFC 1270,
       Clearpoint Research Corporation, October 1991.

   [6] Postel J., "User Datagram Protocol", STD 6, RFC 768,
       USC/Information Sciences Institute, August 1980.

   [7] Information processing systems - Open Systems Interconnection -
       Transport Service Definition - Addendum 1: Connectionless-mode
       Transmission, International Organization for Standardization.
       International Standard 8072/AD 1, June 1986.







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RFC 1418                     SNMP over OSI                    March 1993


   [8] Information processing systems - Open Systems Interconnection -
       Protocol Specification for Providing the Connectionless-mode
       Transport Service, International Organization for
       Standardization.  International Standard 8602, December 1987.

5.  Security Considerations

   Security issues are not discussed in this memo.

6. Author's Address

   Marshall T. Rose
   Dover Beach Consulting, Inc.
   420 Whisman Court
   Mountain View, CA 94043-2112

   Phone: (415) 968-1052
   EMail: mrose@dbc.mtview.ca.us

































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