Stream Control Transmission Protocol (SCTP) Network Address Translation Support
draft-ietf-tsvwg-natsupp-15

Document Type Active Internet-Draft (tsvwg WG)
Last updated 2019-11-17
Replaces draft-ietf-behave-sctpnat, draft-stewart-natsupp-tsvwg
Stream IETF
Intended RFC status Proposed Standard
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Stream WG state WG Document (wg milestone: Feb 2020 - Submit 'SCTP NAT Sup... )
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Network Working Group                                         R. Stewart
Internet-Draft                                             Netflix, Inc.
Intended status: Standards Track                               M. Tuexen
Expires: May 20, 2020                                       I. Ruengeler
                                        Muenster Univ. of Appl. Sciences
                                                       November 17, 2019

Stream Control Transmission Protocol (SCTP) Network Address Translation
                                Support
                      draft-ietf-tsvwg-natsupp-15

Abstract

   The Stream Control Transmission Protocol (SCTP) provides a reliable
   communications channel between two end-hosts in many ways similar to
   the Transmission Control Protocol (TCP).  With the widespread
   deployment of Network Address Translators (NAT), specialized code has
   been added to NAT for TCP that allows multiple hosts to reside behind
   a NAT and yet use only a single globally unique IPv4 address, even
   when two hosts (behind a NAT) choose the same port numbers for their
   connection.  This additional code is sometimes classified as Network
   Address and Port Translation (NAPT).

   This document describes the protocol extensions required for the SCTP
   endpoints and the mechanisms for NAT devices necessary to provide
   similar features of NAPT in the single point and multi point
   traversal scenario.

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
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   This Internet-Draft will expire on May 20, 2020.

Stewart, et al.           Expires May 20, 2020                  [Page 1]
Internet-Draft              SCTP NAT Support               November 2019

Copyright Notice

   Copyright (c) 2019 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
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Conventions . . . . . . . . . . . . . . . . . . . . . . . . .   5
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   5
   4.  Motivation  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     4.1.  SCTP NAT Traversal Scenarios  . . . . . . . . . . . . . .   6
       4.1.1.  Single Point Traversal  . . . . . . . . . . . . . . .   6
       4.1.2.  Multi Point Traversal . . . . . . . . . . . . . . . .   7
     4.2.  Limitations of Classical NAPT for SCTP  . . . . . . . . .   8
     4.3.  The SCTP-Specific Variant of NAT  . . . . . . . . . . . .   8
   5.  Data Formats  . . . . . . . . . . . . . . . . . . . . . . . .  12
     5.1.  Modified Chunks . . . . . . . . . . . . . . . . . . . . .  12
       5.1.1.  Extended ABORT Chunk  . . . . . . . . . . . . . . . .  12
       5.1.2.  Extended ERROR Chunk  . . . . . . . . . . . . . . . .  13
     5.2.  New Error Causes  . . . . . . . . . . . . . . . . . . . .  13
       5.2.1.  VTag and Port Number Collision Error Cause  . . . . .  14
       5.2.2.  Missing State Error Cause . . . . . . . . . . . . . .  14
       5.2.3.  Port Number Collision Error Cause . . . . . . . . . .  15
     5.3.  New Parameters  . . . . . . . . . . . . . . . . . . . . .  16
       5.3.1.  Disable Restart Parameter . . . . . . . . . . . . . .  16
       5.3.2.  VTags Parameter . . . . . . . . . . . . . . . . . . .  16
   6.  Procedures for SCTP Endpoints and NAT Devices . . . . . . . .  18
     6.1.  Association Setup Considerations for Endpoints  . . . . .  18
     6.2.  Handling of Internal Port Number and Verification Tag
           Collisions  . . . . . . . . . . . . . . . . . . . . . . .  19
       6.2.1.  NAT Device Considerations . . . . . . . . . . . . . .  19
       6.2.2.  Endpoint Considerations . . . . . . . . . . . . . . .  19
     6.3.  Handling of Internal Port Number Collisions . . . . . . .  20
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