Stream Control Transmission Protocol Applicability Statement
RFC 3257

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Network Working Group                                           L. Coene
Request for Comments: 3257                                       Siemens
Category: Informational                                       April 2002

      Stream Control Transmission Protocol Applicability Statement

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

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

Abstract

   This document describes the applicability of the Stream Control
   Transmission Protocol (SCTP).  It also contrasts SCTP with the two
   dominant transport protocols, User Datagram Protocol (UDP) &
   Transmission Control Protocol (TCP), and gives some guidelines for
   when best to use SCTP and when not best to use SCTP.

Table of contents

   1. Introduction ..................................................  2
   1.1 Terminology ..................................................  2
   2 Transport protocols ............................................  2
   2.1 TCP service model ............................................  2
   2.2 SCTP service model ...........................................  3
   2.3 UDP service model ............................................  4
   3 SCTP Multihoming issues ........................................  4
   4 SCTP Network Address Translators (NAT) issues [RFC2663] ........  5
   5 Security Considerations ........................................  6
   5.1 Security issues with TCP .....................................  6
   5.2 Security issues with SCTP ....................................  7
   5.3 Security issues with both TCP and SCTP .......................  8
   6 References and related work ....................................  9
   7 Acknowledgments ................................................ 10
   Appendix A: Major functions provided by SCTP ..................... 11
   Editor's Address ................................................. 12
   Full Copyright Statement ......................................... 13

Coene                        Informational                      [Page 1]
RFC 3257              SCTP Applicability Statement            April 2002

1 Introduction

   SCTP is a reliable transport protocol [RFC2960], which along with TCP
   [RFC793], RTP [RFC1889], and UDP [RFC768], provides transport-layer
   services for upper layer protocols and services.  UDP, RTP, TCP, and
   SCTP are currently the IETF standards-track transport-layer
   protocols.  Each protocol has a domain of applicability and services
   it provides, albeit with some overlaps.

   By clarifying the situations where the functionality of these
   protocols are applicable, this document can guide implementers and
   protocol designers in selecting which protocol to use.

   Special attention is given to services SCTP provides which would make
   a decision to use SCTP the right one.

   Major functions provided by SCTP can be found in Appendix A.

1.1 Terminology

   The following terms are commonly identified in this work:

   Association: SCTP connection between two endpoints.

   Transport address: A combination of IP address and SCTP port number.

   Upper layer: The user of the SCTP protocol, which may be an
   adaptation layer, a session layer protocol, or the user application
   directly.

   Multihoming: Assigning more than one IP network interface to a single
   endpoint.

2 Transport protocols

2.1 TCP service model

   TCP is a connection-oriented (a.k.a., session-oriented) transport
   protocol.  This means that it requires both the establishment of a
   connection prior to the exchange of application data and a connection
   tear-down to release system resources after the completion of data
   transfer.

   TCP is currently the most widely used connection-oriented transport
   protocol for the Internet.

Coene                        Informational                      [Page 2]
RFC 3257              SCTP Applicability Statement            April 2002

   TCP provides the upper layer with the following transport services:

   - data reliability;

   - data sequence preservation; and

   - flow and congestion control.

2.2 SCTP service model

   SCTP is also connection-oriented and provides all the transport
   services that TCP provides.  Many Internet applications therefore
   should find that either TCP or SCTP will meet their transport
   requirements.  Note, for applications conscious about processing
   cost, there might be a difference in processing cost associated with
   running SCTP with only a single ordered stream and one address pair
   in comparison to running TCP.

   However, SCTP has some additional capabilities that TCP lacks and
   This can make SCTP a better choice for some applications and
   environments:

   - multi-streams support:

   SCTP supports the delivery of multiple independent user message