Subtype Capability Exchange During MPTCP Handshake
draft-kang-tcpm-subtype-capability-exchange-00

Document Type Active Internet-Draft (individual)
Authors Jiao Kang  , liangqiandeng 
Last updated 2021-02-06
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TCP Maintenance and Minor Extensions                        J. Kang, Ed.
Internet-Draft                                                  Q. Liang
Intended status: Informational                                    Huawei
Expires: 10 August 2021                                  6 February 2021

           Subtype Capability Exchange During MPTCP Handshake
             draft-kang-tcpm-subtype-capability-exchange-00

Abstract

   Multipath TCP provides the ability to simultaneously use multiple
   paths between peers.  MPTCP protocol defines seven subtypes in MPTCP
   v0 [RFC6824] and ten subtypes in MPTCP v1 [RFC8684] to differentiate
   message types and implement some additional functions during a
   session.

   This draft proposes an enhancement to support Subtype Capability
   Exchange during MPTCP connection establishment in order to improve
   elastic scalability of MPTCP protocol.  It includes: 1) requirements
   for which this kind of capability exchange during handshake is
   important for a MPTCP session; 2) a typical flow for Subtype
   Capability Exchange between peers; 3) a feasible solution on protocol
   design is suggested.

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
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   Drafts is at https://datatracker.ietf.org/drafts/current/.

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

   This Internet-Draft will expire on 10 August 2021.

Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Internet-Draft            Subtype-Cap Exchange             February 2021

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   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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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   2
     1.2.  Background  . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  One Typical Flow  . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Protocol Implementation . . . . . . . . . . . . . . . . . . .   5
     3.1.  Carrying Subtype Capabilities in MP_CAPABLE Option  . . .   5
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

1.1.  Requirements Language

   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 RFC 2119 [RFC2119].

1.2.  Background

   Table 1 lists all subtypes that have been specified in current MPTCP
   versions.  Besides version negotiation, MPTCP peers can not interact
   with each other on the granularity of subtype capability.  This
   feature may cause inflexible protocol extension.  For example, if a
   new message type A is added in future extension, a higher version
   should be released to import it and a new subtype may need to be
   allocated.  Another case is that if a sender does not know the
   subtypes supported by a receiver in a MPTCP session, as a result,
   invalid data packets may been sent from the sender during data
   transmission and the receiver will discard it which causes system
   overhead on receiver side.

Kang & Liang             Expires 10 August 2021                 [Page 2]
Internet-Draft            Subtype-Cap Exchange             February 2021

    +=======+=================+===============+===========+===========+
    | Value | Symbol          | Name          | MPTCPv0   | MPTCPv1   |
    +=======+=================+===============+===========+===========+
    | 0x0   | MP_CAPABLE      | Multipath     | Supported | Supported |
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