Stream Control Transmission Protocol (SCTP) Network Address Translation Support
draft-ietf-tsvwg-natsupp-20

Document Type Active Internet-Draft (tsvwg WG)
Last updated 2020-08-01 (latest revision 2020-07-28)
Replaces draft-ietf-behave-sctpnat, draft-stewart-natsupp-tsvwg
Stream IETF
Intended RFC status Proposed Standard
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- Yang catalog entry for ietf-nat-sctp@2019-11-18.yang
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Network Working Group                                      R. R. Stewart
Internet-Draft                                             Netflix, Inc.
Intended status: Standards Track                                M. Tüxen
Expires: 29 January 2021                                     I. Rüngeler
                                         Münster Univ. of Appl. Sciences
                                                            28 July 2020

Stream Control Transmission Protocol (SCTP) Network Address Translation
                                Support
                      draft-ietf-tsvwg-natsupp-20

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 functions for TCP that allows multiple hosts to
   reside behind a NAT function and yet share a single IPv4 address,
   even when two hosts (behind a NAT function) 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 functions necessary to provide
   similar features of NAPT in the single point and multi point
   traversal scenario.

   Finally, a YANG module for SCTP NAT is defined.

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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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 29 January 2021.

Stewart, et al.          Expires 29 January 2021                [Page 1]
Internet-Draft              SCTP NAT Support                   July 2020

Copyright Notice

   Copyright (c) 2020 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 (https://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
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   provided without warranty as 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  . . . . . . . . . . . . . . .   7
       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  . . . . . . . . . . . . . . . . . . . . . . . .  13
     5.1.  Modified Chunks . . . . . . . . . . . . . . . . . . . . .  13
       5.1.1.  Extended ABORT Chunk  . . . . . . . . . . . . . . . .  13
       5.1.2.  Extended ERROR Chunk  . . . . . . . . . . . . . . . .  13
     5.2.  New Error Causes  . . . . . . . . . . . . . . . . . . . .  14
       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 Functions . . . . . . .  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 Function Considerations . . . . . . . . . . . . .  19
       6.2.2.  Endpoint Considerations . . . . . . . . . . . . . . .  20
     6.3.  Handling of Internal Port Number Collisions . . . . . . .  20
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