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Checking references for intended status: Experimental ---------------------------------------------------------------------------- ** Obsolete normative reference: RFC 6824 (Obsoleted by RFC 8684) == Outdated reference: A later version (-07) exists of draft-ietf-mptcp-experience-03 Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group M. Boucadair 3 Internet-Draft C. Jacquenet 4 Intended status: Experimental Orange 5 Expires: June 9, 2016 December 7, 2015 7 Negotiating the Maximum Number of Multipath TCP (MPTCP) Subflows 8 draft-boucadair-mptcp-max-subflow-01 10 Abstract 12 This document specifies an experimental Multipath TCP (MPTCP) option 13 that is meant to negotiate the maximum number of subflows that can be 14 established and maintained for a given MPTCP connection. The purpose 15 is to minimize any possible performance degradation that can be 16 induced by a possibly large number of establishment requests for 17 additional subflows if the remote endpoint is not appropriately 18 dimensioned to handle such requests. 20 Requirements Language 22 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 23 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 24 document are to be interpreted as described in RFC 2119 [RFC2119]. 26 Status of This Memo 28 This Internet-Draft is submitted in full conformance with the 29 provisions of BCP 78 and BCP 79. 31 Internet-Drafts are working documents of the Internet Engineering 32 Task Force (IETF). Note that other groups may also distribute 33 working documents as Internet-Drafts. The list of current Internet- 34 Drafts is at http://datatracker.ietf.org/drafts/current/. 36 Internet-Drafts are draft documents valid for a maximum of six months 37 and may be updated, replaced, or obsoleted by other documents at any 38 time. It is inappropriate to use Internet-Drafts as reference 39 material or to cite them other than as "work in progress." 41 This Internet-Draft will expire on June 9, 2016. 43 Copyright Notice 45 Copyright (c) 2015 IETF Trust and the persons identified as the 46 document authors. All rights reserved. 48 This document is subject to BCP 78 and the IETF Trust's Legal 49 Provisions Relating to IETF Documents 50 (http://trustee.ietf.org/license-info) in effect on the date of 51 publication of this document. Please review these documents 52 carefully, as they describe your rights and restrictions with respect 53 to this document. Code Components extracted from this document must 54 include Simplified BSD License text as described in Section 4.e of 55 the Trust Legal Provisions and are provided without warranty as 56 described in the Simplified BSD License. 58 Table of Contents 60 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 61 1.1. Experiment Goals . . . . . . . . . . . . . . . . . . . . 3 62 2. Maximum Subflows MPTCP Option (MP_MAXSUBFLOW) . . . . . . . . 3 63 3. Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . 3 64 4. Security Considerations . . . . . . . . . . . . . . . . . . . 4 65 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 66 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 67 6.1. Normative References . . . . . . . . . . . . . . . . . . 4 68 6.2. Informative References . . . . . . . . . . . . . . . . . 4 69 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 71 1. Introduction 73 This document specifies a Multipath TCP (MPTCP, [RFC6824]) option 74 that is meant to indicate to a remote peer the maximum number of 75 subflows that can be established within a single MPTCP connection. 76 If the remote peer honors the indication provided in this option, any 77 performance degradation induced by a possibly abusive setup of 78 additional subflows that exceed the said maximum becomes unlikely. 80 This document adheres to [I-D.bonaventure-mptcp-exp-option]. 82 This option targets mainly MPTCP deployments within a single 83 administrative domain such as those MPTCP designs meant to achieve 84 load-balancing, for example. The use of this option contributes to 85 the harmonization of node configuration within an administrative 86 domain, so that an optimal number of subflows is maintained by 87 involved nodes independently of their actual performance 88 capabilities. This option can be used for other deployment 89 scenarios. It is out of scope of this document to identify an 90 exhaustive list of such scenarios. 92 Section 3.4 of [I-D.ietf-mptcp-experience] includes a discussion on 93 the MPTCP session manager issues 95 1.1. Experiment Goals 97 Experiments based upon the MPTCP option described in this document 98 are meant to help operators refine their MPTCP design and operational 99 procedures, by tweaking some MPTCP parameters such as the number of 100 subflows to be associated with a given MPTCP connection. 101 Experimenting with this MPTCP option should also help assess whether 102 this option can be used to propagate MPTCP-related optimization 103 parameters (derived from the number of concurrent subflows associated 104 to each MPTCP connection) that can be configured in a node that is 105 responsible for aggregating MPTCP connections established with 106 upstream nodes. 108 2. Maximum Subflows MPTCP Option (MP_MAXSUBFLOW) 110 This option follows the shared experimental format defined in 111 [I-D.bonaventure-mptcp-exp-option] (see Figure 1). 113 1 2 3 114 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 115 +---------------+---------------+-------+-----------------------+ 116 | Kind | Length |Subtype| Flags | Experiment | 117 +---------------+---------------+-------+-------+---------------+ 118 | Id. (16 bits) | Maximum Sub-Flows | 119 +---------------+-----------------------------------------------+ 121 Figure 1: Option Format 123 The meaning of "Kind", "Length", "Subtype", and "Flags" (especially 124 'S' and 'U' flags) are exactly the same as defined in 125 [I-D.bonaventure-mptcp-exp-option]. 127 Experiment ID (to be assigned, see Section 5). 129 The "Maximum Sub-Flows" field indicates the number of maximum 130 concurrent subflows that can be maintained by a given MPTCP endpoint 131 for each MPTCP connection established by or with this endpoint. The 132 value of this field MUST be strictly greater than zero. 134 3. Behavior 136 The option defined in Section 2 MAY be used by a TCP endpoint to 137 indicate to its corresponding peer the maximum number of subflows 138 that it can maintain per MPTCP connection. 140 If two peers (T1 and T2) indicate the maximum number of concurrent 141 subflows per connection they can maintain, then they MUST NOT 142 maintain more than "MIN(MAX_SUBFLOW(T1), MAX_SUBFLOW(T2))" concurrent 143 subflows. 145 The absence of the MP_MAXSUBFLOW option in an MPTCP control message 146 issued by a MPTCP endpoint is an indication that this endpoint can 147 instantiate any number of subflows per MPTCP connection. 149 4. Security Considerations 151 MPTCP-related security considerations are documented in [RFC6824] and 152 [RFC7430]. 154 5. IANA Considerations 156 This document requests IANA to assign an experiment ID for 157 MP_MAXSUBFLOW as per [I-D.bonaventure-mptcp-exp-option]. 159 6. References 161 6.1. Normative References 163 [I-D.bonaventure-mptcp-exp-option] 164 Bonaventure, O., benjamin.hesmans@uclouvain.be, b., and M. 165 Boucadair, "Experimental Multipath TCP option", draft- 166 bonaventure-mptcp-exp-option-00 (work in progress), June 167 2015. 169 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 170 Requirement Levels", BCP 14, RFC 2119, 171 DOI 10.17487/RFC2119, March 1997, 172 . 174 [RFC6824] Ford, A., Raiciu, C., Handley, M., and O. Bonaventure, 175 "TCP Extensions for Multipath Operation with Multiple 176 Addresses", RFC 6824, DOI 10.17487/RFC6824, January 2013, 177 . 179 6.2. Informative References 181 [I-D.ietf-mptcp-experience] 182 Bonaventure, O., Paasch, C., and G. Detal, "Use Cases and 183 Operational Experience with Multipath TCP", draft-ietf- 184 mptcp-experience-03 (work in progress), October 2015. 186 [RFC7430] Bagnulo, M., Paasch, C., Gont, F., Bonaventure, O., and C. 187 Raiciu, "Analysis of Residual Threats and Possible Fixes 188 for Multipath TCP (MPTCP)", RFC 7430, 189 DOI 10.17487/RFC7430, July 2015, 190 . 192 Authors' Addresses 194 Mohamed Boucadair 195 Orange 196 Rennes 35000 197 France 199 Email: mohamed.boucadair@orange.com 201 Christian Jacquenet 202 Orange 203 Rennes 35000 204 France 206 Email: christian.jacquenet@orange.com