Simple Network Management Protocol Over Transmission Control Protocol Transport Mapping
RFC 3430

Document Type RFC - Experimental (December 2002; No errata)
Was draft-irtf-nmrg-snmp-tcp (individual in ops area)
Last updated 2015-10-14
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IESG note Published as RFC 3430
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Network Working Group                                   J. Schoenwaelder
Request for Comments: 3430                               TU Braunschweig
Category: Experimental                                     December 2002

             Simple Network Management Protocol (SNMP) over
         Transmission Control Protocol (TCP) Transport Mapping

Status of this Memo

   This memo defines an Experimental Protocol for the Internet
   community.  It does not specify an Internet standard of any kind.
   Discussion and suggestions for improvement are requested.
   Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2002).  All Rights Reserved.

Abstract

   This memo defines a transport mapping for using the Simple Network
   Management Protocol (SNMP) over TCP.  The transport mapping can be
   used with any version of SNMP.  This document extends the transport
   mappings defined in STD 62, RFC 3417.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.  SNMP over TCP  . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.1 Serialization  . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.2 Well-Known Values  . . . . . . . . . . . . . . . . . . . . . .  3
   2.3 Connection Management  . . . . . . . . . . . . . . . . . . . .  3
   2.4 Reliable Transport versus Confirmed Operations . . . . . . . .  4
   3.  Security Considerations  . . . . . . . . . . . . . . . . . . .  5
   4.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . .  6
       References . . . . . . . . . . . . . . . . . . . . . . . . . .  6
   A.  Connection Establishment Alternatives  . . . . . . . . . . . .  8
       Author's Address . . . . . . . . . . . . . . . . . . . . . . .  9
       Full Copyright Statement . . . . . . . . . . . . . . . . . . . 10

Schoenwaelder                 Experimental                      [Page 1]
RFC 3430            SNMP over TCP Transport Mapping        December 2002

1. Introduction

   This memo defines a transport mapping for using the Simple Network
   Management Protocol (SNMP) [1] over TCP [2].  The transport mapping
   can be used with any version of SNMP.  This document extends the
   transport mappings defined in STD 62, RFC 3417 [3].

   The SNMP over TCP transport mapping is an optional transport mapping.
   SNMP protocol engines that implement the SNMP over TCP transport
   mapping MUST also implement the SNMP over UDP transport mapping as
   defined in STD 62, RFC 3417 [3].

   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 BCP 14, RFC 2119 [4].

2. SNMP over TCP

   SNMP over TCP is an optional transport mapping.  It is primarily
   defined to support more efficient bulk transfer mechanisms within the
   SNMP framework [5].

   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, since TCP has a larger footprint on resource usage than UDP,
   engines 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).

   When selecting the transport, it is useful to consider how SNMP
   interacts with TCP acknowledgments and timers.  In particular,
   infrequent SNMP interactions over TCP may lead to additional IP
   packets carrying acknowledgments for SNMP responses if there is no
   chance to piggyback them.  Furthermore, it is recommended to
   configure SNMP retransmission timers to fire later when using SNMP
   over TCP to avoid application specific timeouts before the TCP timers
   have expired.

2.1 Serialization

   Each instance of a message is serialized into a single BER-encoded
   message, using the algorithm specified in Section 8 of STD 62, RFC
   3417 [3].  The BER-encoded message is then sent over a TCP

Schoenwaelder                 Experimental                      [Page 2]
RFC 3430            SNMP over TCP Transport Mapping        December 2002

   connection.  An SNMP engine MUST NOT interleave SNMP messages within
   the TCP byte stream.

   All the bytes of one SNMP message must be sent before any bytes of a
   different SNMP message.

   It is possible to exchange multiple SNMP request/response pairs over
   a single (persistent) TCP connection.  TCP connections are by default
   full-duplex and data can travel in both directions at different
   speeds.  It is therefore possible to send multiple SNMP messages to a
   remote SNMP engine before receiving responses from the same SNMP
   engine.  Note that an SNMP engine is not required to return responses
   in the same order as it received the requests.
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