Network Working Group                           J. Schoenwaelder, Editor
Internet-Draft                                           TU Braunschweig
Expires December 1999                                       10 June 1999

                    SNMP-over-TCP Transport Mapping

                   <draft-irtf-nmrg-snmp-tcp-01.txt>

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC 2026.  Internet-Drafts are
   working documents of the Internet Engineering Task Force (IETF), its
   areas, and its working groups. Note that other groups may also
   distribute working documents as Internet-Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time. It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html

   Distribution of this document is unlimited. Please send comments to
   the Network Management Research Group, <nmrg@ibr.cs.tu-bs.de>.

Copyright Notice

   Copyright (C) The Internet Society (1999). All Rights Reserved.

Abstract

   This memo defines a transport mapping for using the Simple Network
   Management Protocol (SNMP) over TCP. The transport mapping defined in
   this memo can be used with any version of SNMP.

J. Schoenwaelder                                                [Page 1]


Internet-Draft      SNMP-over-TCP Transport Mapping            June 1999

   Table of Contents

   1 Introduction .................................................    3
   2 Definitions ..................................................    3
   3 SNMP over TCP ................................................    4
   3.1 Serialization ..............................................    4
   3.2 Well-Known Values ..........................................    4
   3.3 Connection Management ......................................    5
   4 Acknowledgments ..............................................    5
   5 References ...................................................    6
   6 Editor's Address .............................................    6
   7 Full Copyright Statement .....................................    7

J. Schoenwaelder                                                [Page 2]


Internet-Draft      SNMP-over-TCP Transport Mapping            June 1999

1.  Introduction

   This memo defines a transport mapping for using the Simple Network
   Management Protocol (SNMP) over TCP. The transport mapping defined in
   this memo can be used with any version of SNMP. This document extends
   the transport mappings defined in RFC 1906 [1].

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [2].

2.  Definitions

   IRTF-NMRG-SNMP-TM DEFINITIONS ::= BEGIN

   IMPORTS
       MODULE-IDENTITY, OBJECT-IDENTITY, experimental
           FROM SNMPv2-SMI
       TEXTUAL-CONVENTION
           FROM SNMPv2-TC;

   nmrgSnmpDomains MODULE-IDENTITY
       LAST-UPDATED "9906101100Z"
       ORGANIZATION "IRTF Network Management Research Group"
       CONTACT-INFO
           "Juergen Schoenwaelder
            TU Braunschweig
            Bueltenweg 74/75
            38106 Braunschweig
            Germany

            Phone: +49 531 391-3283
            Email: schoenw@ibr.cs.tu-bs.de"
       DESCRIPTION
           "This MIB module defines the SNMP-over-TCP transport mapping."
       ::= { experimental nmrg(91) 1 }

   -- SNMP over TCP over IPv4

   snmpTCPDomain   OBJECT-IDENTITY
       STATUS      current
       DESCRIPTION
           "The SNMP-over-TCP-over-IPv4 transport domain. The
            corresponding transport address is of type SnmpTCPAddress."
       ::= { nmrgSnmpDomains 6 }   -- matches first unused value
                                   -- below snmpDomains

   SnmpTCPAddress ::= TEXTUAL-CONVENTION
       DISPLAY-HINT "1d.1d.1d.1d/2d"

J. Schoenwaelder                                                [Page 3]


Internet-Draft      SNMP-over-TCP Transport Mapping            June 1999

       STATUS       current
       DESCRIPTION
               "Represents a TCP/IPv4 address:

                  octets   contents        encoding
                   1-4     IP-address      network-byte order
                   5-6     TCP-port        network-byte order
               "
       SYNTAX      OCTET STRING (SIZE (6))

   END

3.  SNMP over TCP

   SNMP over TCP is an optional transport mapping. Implementors are
   encouraged to support SNMP over TCP whenever possible because this
   enables applications to make more efficient bulk transfers of MIB
   data [3].

   The originator of a request/response transaction chooses the
   transport protocol for the entire transaction. The transport protocol
   MUST NOT change during a transaction.

   In general, originators of request/response transactions are free to
   use the transport they assume is the best in a given situation.
   However, as TCP has a larger footprint on resource usage than UDP,
   applications using SNMP over TCP may choose to switch back to UDP by
   refusing new TCP connections whenever necessary (e.g. too many open
   TCP connections).

3.1.  Serialization

   Each instance of a message is serialized into a single BER-encoded
   message, using the algorithm specified in Section 8 of RFC 1906 [1].
   The BER-encoded message is then sent over a TCP connection.

   It is possible to exchange multiple SNMP request/response pairs over
   a single (persistent) TCP connection. The length field in the BER-
   encoded SNMP message is used to separate multiple requests sent over
   a single TCP connection.

3.2.  Well-Known Values

   It is RECOMMENDED that administrators configure their SNMP entities
   containing command generators to listen on TCP port 161 for incoming
   connections. It is also RECOMMENDED that SNMP entities containing
   notification receivers be configured to listen on TCP port 162 for

J. Schoenwaelder                                                [Page 4]


Internet-Draft      SNMP-over-TCP Transport Mapping            June 1999

   connection requests.

   When an SNMP entity uses the TCP transport mapping, it MUST be
   capable of accepting messages that are at least 8192 octets in size.
   Implementation of larger values is encouraged whenever possible.

3.3.  Connection Management

   The use of TCP connections introduces costs. Connection establishment
   and teardown cause additional network traffic. Furthermore,
   maintaining open connections binds resources in the network layer of
   the underlying operating system.

   TCP connections are intended to be used when the size of the
   transferred data is large. If a connectionless transport were used
   instead, its small packet-size constraint would cause latency to
   increase excessively.

   Another advantage of using TCP connections, regardless of the message
   size, is that you do not need to implement retransmissions at the
   application level. This may result in simpler management
   applications.

   All SNMP entities (whether in an agent role or manager role) can
   close TCP connections at any point in time. This ensures that SNMP
   entities can control their resource usage and shut down TCP
   connections that are not used. SNMP engines SHOULD NOT process any
   outstanding requests if the underlying TCP connection has been
   closed. A `noResponse' error condition SHOULD be signalled for
   outstanding requests for command generator applications if the TCP
   connection is closed before a response has been received.

4.  Acknowledgments

   The definitions in this memo are inspired by definitions found in RFC
   1906 [1]. This document is the result of discussions of the Network
   Management Research Group (NMRG). Special thanks go to the following
   participants for their comments and contributions:

   Luca Deri, Jean-Philippe Martin-Flatin, Aiko Pras, Ron Sprenkels,
   Bert Wijnen.

J. Schoenwaelder                                                [Page 5]


Internet-Draft      SNMP-over-TCP Transport Mapping            June 1999

5.  References

   [1]  Case, J., McCloghrie, K., Rose, M., and S. Waldbusser,
        "Transport Mappings for Version 2 of the Simple Network
        Management Protocol (SNMPv2)", RFC 1906, January 1996.

   [2]  Bradner, S., "Key words for use in RFCs to Indicate Requirement
        Levels", BCP 14, RFC 2119, March 1997.

   [3]  Sprenkels, R., and J.P. Martin-Flatin, "Bulk Transfers of MIB
        Data", The Simple Times, Vol. 7, No. 1, pp. 1-7, March 1999.

6.  Editor's Address

   Juergen Schoenwaelder
   TU Braunschweig
   Bueltenweg 74/75
   38106 Braunschweig
   Germany

   Phone: +49 531 391-3283
   EMail: schoenw@ibr.cs.tu-bs.de

J. Schoenwaelder                                                [Page 6]


Internet-Draft      SNMP-over-TCP Transport Mapping            June 1999

7.  Full Copyright Statement

   Copyright (C) The Internet Society (1999). All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works. However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.

   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

J. Schoenwaelder                                                [Page 7]