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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  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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  [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: [email protected]

































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