RFC 3430 (rfc3430) - Page 2 of 10

Simple Network Management Protocol Over Transmission Control Protocol Transport Mapping

Alternative Format: Original Text Document
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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
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