UDP Encapsulation of SCTP Packets
draft-ietf-tsvwg-sctp-udp-encaps-02

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Network Working Group                                          M. Tuexen
Internet-Draft                          Muenster Univ. of Appl. Sciences
Intended status: Standards Track                              R. Stewart
Expires: June 10, 2012                                    Adara Networks
                                                        December 8, 2011

                   UDP Encapsulation of SCTP Packets
                draft-ietf-tsvwg-sctp-udp-encaps-02.txt

Abstract

   This document describes a simple method of encapsulating SCTP Packets
   into UDP packets and its limitations.  This allows the usage of SCTP
   in networks with legacy NAT not supporting SCTP.  It can also be used
   to implement SCTP on hosts without directly accessing the IP-layer,
   for example implementing it as part of the application without
   requiring special privileges.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   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."

   This Internet-Draft will expire on June 10, 2012.

Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of

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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Use Cases  . . . . . . . . . . . . . . . . . . . . . . . . . .  3
     3.1.  Portable SCTP Implementations  . . . . . . . . . . . . . .  3
     3.2.  Legacy NAT traversal . . . . . . . . . . . . . . . . . . .  4
   4.  SCTP over UDP  . . . . . . . . . . . . . . . . . . . . . . . .  4
     4.1.  Architectural Considerations . . . . . . . . . . . . . . .  4
     4.2.  Packet Format  . . . . . . . . . . . . . . . . . . . . . .  4
     4.3.  Encapsulation Procedure  . . . . . . . . . . . . . . . . .  6
     4.4.  Decapsulation Procedure  . . . . . . . . . . . . . . . . .  6
     4.5.  ICMP considerations  . . . . . . . . . . . . . . . . . . .  6
     4.6.  Path MTU considerations  . . . . . . . . . . . . . . . . .  7
     4.7.  Handling of Embedded IP-addresses  . . . . . . . . . . . .  7
     4.8.  ECN considerations . . . . . . . . . . . . . . . . . . . .  7
   5.  Socket API Considerations  . . . . . . . . . . . . . . . . . .  7
     5.1.  Get or Set the Remote UDP Encapsulation Port Number
           (SCTP_REMOTE_UDP_ENCAPS_PORT)  . . . . . . . . . . . . . .  7
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  8
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . .  8
   8.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . .  8
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . .  8
     9.1.  Normative References . . . . . . . . . . . . . . . . . . .  8
     9.2.  Informative References . . . . . . . . . . . . . . . . . .  9
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10

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1.  Introduction

   This document describes a simple method of encapsulating SCTP packets
   into UDP packets.  SCTP as defined in [RFC4960] runs directly over
   IPv4 or IPv6.  There are two main reasons for encapsulating SCTP
   packets:

   o  Allow SCTP traffic to pass legacy NATs, which do not provide
      native SCTP support as specified in [I-D.ietf-behave-sctpnat] and
      [I-D.ietf-tsvwg-natsupp].

   o  Allow SCTP to be implemented on hosts which do not provide direct
      access to the IP-layer.  In particular, applications can use their
      own SCTP implementation if the operating system does not provide