draft-ietf-tcpm-converters-01.txt		draft-ietf-tcpm-converters-02.txt
	TCPM Working Group O. Bonaventure, Ed.		TCPM Working Group O. Bonaventure, Ed.
	Internet-Draft Tessares		Internet-Draft Tessares
	Intended status: Experimental M. Boucadair, Ed.		Intended status: Experimental M. Boucadair, Ed.
	Expires: September 6, 2018 Orange		Expires: January 2, 2019 Orange
	B. Peirens		S. Gundavelli
	Proximus		Cisco
	S. Seo		S. Seo
	Korea Telecom		Korea Telecom
	A. Nandugudi		July 01, 2018
	Memphis University
	March 05, 2018
	0-RTT TCP Convert Protocol		0-RTT TCP Convert Protocol
	draft-ietf-tcpm-converters-01		draft-ietf-tcpm-converters-02
	Abstract		Abstract
	This document specifies an application proxy, called Transport		This document specifies an application proxy, called Transport
	Converter, to assist the deployment of TCP extensions such as		Converter, to assist the deployment of TCP extensions such as
	Multipath TCP. This proxy is designed to avoid inducing extra delay		Multipath TCP. This proxy is designed to avoid inducing extra delay
	when involved in a network-assisted connection (that is, 0-RTT).		when involved in a network-assisted connection (that is, 0-RTT).
	This specification assumes an explicit model, where the proxy is		This specification assumes an explicit model, where the proxy is
	explicitly configured on hosts.		explicitly configured on hosts.
	skipping to change at page 2, line 4 ¶		skipping to change at page 1, line 48 ¶
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at https://datatracker.ietf.org/drafts/current/.		Drafts is at https://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on September 6, 2018.
			This Internet-Draft will expire on January 2, 2019.
	Copyright Notice		Copyright Notice
	Copyright (c) 2018 IETF Trust and the persons identified as the		Copyright (c) 2018 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(https://trustee.ietf.org/license-info) in effect on the date of		(https://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	skipping to change at page 2, line 40 ¶		skipping to change at page 2, line 39 ¶
	3.4. Sample Example of Incoming Converter-Assisted Multipath		3.4. Sample Example of Incoming Converter-Assisted Multipath
	TCP Connection . . . . . . . . . . . . . . . . . . . . . 11		TCP Connection . . . . . . . . . . . . . . . . . . . . . 11
	4. The Converter Protocol (Convert) . . . . . . . . . . . . . . 12		4. The Converter Protocol (Convert) . . . . . . . . . . . . . . 12
	4.1. The Convert Fixed Header . . . . . . . . . . . . . . . . 12		4.1. The Convert Fixed Header . . . . . . . . . . . . . . . . 12
	4.2. Convert TLVs . . . . . . . . . . . . . . . . . . . . . . 13		4.2. Convert TLVs . . . . . . . . . . . . . . . . . . . . . . 13
	4.2.1. Generic Convert TLV Format . . . . . . . . . . . . . 13		4.2.1. Generic Convert TLV Format . . . . . . . . . . . . . 13
	4.2.2. Summary of Supported Convert TLVs . . . . . . . . . . 14		4.2.2. Summary of Supported Convert TLVs . . . . . . . . . . 14
	4.2.3. The Bootstrap TLV . . . . . . . . . . . . . . . . . . 15		4.2.3. The Bootstrap TLV . . . . . . . . . . . . . . . . . . 15
	4.2.4. Supported TCP Extension Services TLV . . . . . . . . 15		4.2.4. Supported TCP Extension Services TLV . . . . . . . . 15
	4.2.5. Connect TLV . . . . . . . . . . . . . . . . . . . . . 16		4.2.5. Connect TLV . . . . . . . . . . . . . . . . . . . . . 16
	4.2.6. Extended TCP Header TLV . . . . . . . . . . . . . . . 17		4.2.6. Extended TCP Header TLV . . . . . . . . . . . . . . . 18
	4.2.7. Error TLV . . . . . . . . . . . . . . . . . . . . . . 18		4.2.7. Error TLV . . . . . . . . . . . . . . . . . . . . . . 18
	5. Compatibility of Specific TCP Options with the Conversion		5. Compatibility of Specific TCP Options with the Conversion
	Service . . . . . . . . . . . . . . . . . . . . . . . . . . . 21		Service . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
	5.1. Base TCP Options . . . . . . . . . . . . . . . . . . . . 21		5.1. Base TCP Options . . . . . . . . . . . . . . . . . . . . 21
	5.2. Window Scale (WS) . . . . . . . . . . . . . . . . . . . . 21		5.2. Window Scale (WS) . . . . . . . . . . . . . . . . . . . . 22
	5.3. Selective Acknowledgements . . . . . . . . . . . . . . . 22		5.3. Selective Acknowledgements . . . . . . . . . . . . . . . 22
	5.4. Timestamp . . . . . . . . . . . . . . . . . . . . . . . . 22		5.4. Timestamp . . . . . . . . . . . . . . . . . . . . . . . . 22
	5.5. Multipath TCP . . . . . . . . . . . . . . . . . . . . . . 23		5.5. Multipath TCP . . . . . . . . . . . . . . . . . . . . . . 23
	5.6. TCP Fast Open . . . . . . . . . . . . . . . . . . . . . . 23		5.6. TCP Fast Open . . . . . . . . . . . . . . . . . . . . . . 23
	5.7. TCP User Timeout . . . . . . . . . . . . . . . . . . . . 23		5.7. TCP User Timeout . . . . . . . . . . . . . . . . . . . . 24
	5.8. TCP-AO . . . . . . . . . . . . . . . . . . . . . . . . . 24		5.8. TCP-AO . . . . . . . . . . . . . . . . . . . . . . . . . 24
	5.9. TCP Experimental Options . . . . . . . . . . . . . . . . 24		5.9. TCP Experimental Options . . . . . . . . . . . . . . . . 24
	6. Interactions with Middleboxes . . . . . . . . . . . . . . . . 24		6. Interactions with Middleboxes . . . . . . . . . . . . . . . . 24
	7. Security Considerations . . . . . . . . . . . . . . . . . . . 25		7. Security Considerations . . . . . . . . . . . . . . . . . . . 25
	7.1. Privacy & Ingress Filtering . . . . . . . . . . . . . . . 25		7.1. Privacy & Ingress Filtering . . . . . . . . . . . . . . . 25
	7.2. Authorization . . . . . . . . . . . . . . . . . . . . . . 25		7.2. Authorization . . . . . . . . . . . . . . . . . . . . . . 25
	7.3. Denial of Service . . . . . . . . . . . . . . . . . . . . 25		7.3. Denial of Service . . . . . . . . . . . . . . . . . . . . 26
	7.4. Traffic Theft . . . . . . . . . . . . . . . . . . . . . . 26		7.4. Traffic Theft . . . . . . . . . . . . . . . . . . . . . . 26
	7.5. Multipath TCP-specific Considerations . . . . . . . . . . 26		7.5. Multipath TCP-specific Considerations . . . . . . . . . . 26
	8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27		8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27
	8.1. Convert Service Port Number . . . . . . . . . . . . . . . 27		8.1. Convert Service Port Number . . . . . . . . . . . . . . . 27
	8.2. The Converter Protocol (Convert) Parameters . . . . . . . 27		8.2. The Converter Protocol (Convert) Parameters . . . . . . . 27
	8.2.1. Convert Versions . . . . . . . . . . . . . . . . . . 27		8.2.1. Convert Versions . . . . . . . . . . . . . . . . . . 27
	8.2.2. Convert TLVs . . . . . . . . . . . . . . . . . . . . 28		8.2.2. Convert TLVs . . . . . . . . . . . . . . . . . . . . 28
	8.2.3. Convert Error Messages . . . . . . . . . . . . . . . 28		8.2.3. Convert Error Messages . . . . . . . . . . . . . . . 28
	9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 29		9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 29
	9.1. Contributors . . . . . . . . . . . . . . . . . . . . . . 30		9.1. Contributors . . . . . . . . . . . . . . . . . . . . . . 30
	10. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 30		10. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 31
	11. References . . . . . . . . . . . . . . . . . . . . . . . . . 30		11. References . . . . . . . . . . . . . . . . . . . . . . . . . 31
	11.1. Normative References . . . . . . . . . . . . . . . . . . 30		11.1. Normative References . . . . . . . . . . . . . . . . . . 31
	11.2. Informative References . . . . . . . . . . . . . . . . . 31		11.2. Informative References . . . . . . . . . . . . . . . . . 32
	Appendix A. Differences with SOCKSv5 . . . . . . . . . . . . . . 34		Appendix A. Differences with SOCKSv5 . . . . . . . . . . . . . . 35
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 36		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 37
	1. Introduction		1. Introduction
	Transport protocols like TCP evolve regularly [RFC7414]. TCP has		Transport protocols like TCP evolve regularly [RFC7414]. TCP has
	been improved in different ways. Some improvements such as changing		been improved in different ways. Some improvements such as changing
	the initial window size [RFC6928] or modifying the congestion control		the initial window size [RFC6928] or modifying the congestion control
	scheme can be applied independently on clients and servers. Other		scheme can be applied independently on clients and servers. Other
	improvements such as Selective Acknowledgements [RFC2018] or large		improvements such as Selective Acknowledgements [RFC2018] or large
	windows [RFC7323] require a new TCP option or to change the semantics		windows [RFC7323] require a new TCP option or to change the semantics
	of some fields in the TCP header. These modifications must be		of some fields in the TCP header. These modifications must be
	skipping to change at page 4, line 20 ¶		skipping to change at page 4, line 20 ¶
	for bonding purposes, faster handovers, or better resiliency.		for bonding purposes, faster handovers, or better resiliency.
	Unfortunately, deploying those extensions on both a wide range of		Unfortunately, deploying those extensions on both a wide range of
	clients and servers remains difficult.		clients and servers remains difficult.
	More recently, experimentation of 5G bonding, which has very scarce		More recently, experimentation of 5G bonding, which has very scarce
	coverage, has been conducted into global range of the incumbent 4G		coverage, has been conducted into global range of the incumbent 4G
	(LTE) connectivity in newly devised clients using Multipath TCP		(LTE) connectivity in newly devised clients using Multipath TCP
	proxy. Even if the 5G and the 4G bonding by using Multipath TCP		proxy. Even if the 5G and the 4G bonding by using Multipath TCP
	increases the bandwidth to data transfer, it is as well crucial to		increases the bandwidth to data transfer, it is as well crucial to
	minimize latency for all the way between endhosts regardless of		minimize latency for all the way between endhosts regardless of
	whether intermediate nodes are inside or ouside of the mobile core.		whether intermediate nodes are inside or outside of the mobile core.
	In order to handle uRLLC (Ultra-Reliable Low-Latency Communication)		In order to handle uRLLC (Ultra-Reliable Low-Latency Communication)
	for the next generation mobile network, Multipath TCP and its proxy		for the next generation mobile network, Multipath TCP and its proxy
	mechanism must be optimized to reduce latency.		mechanism must be optimised to reduce latency.
	This document specifies an application proxy, called Transport		This document specifies an application proxy, called Transport
	Converter. A Transport Converter is a function that is installed by		Converter. A Transport Converter is a function that is installed by
	a network operator to aid the deployment of TCP extensions and to		a network operator to aid the deployment of TCP extensions and to
	provide the benefits of such extensions to clients. A Transport		provide the benefits of such extensions to clients. A Transport
	Converter may support conversion service for one or more TCP		Converter may support conversion service for one or more TCP
	extensions. This service is provided by means of the Converter		extensions. This service is provided by means of the Converter
	Protocol (Convert), that is an application layer protocol which uses		Protocol (Convert), that is an application layer protocol which uses
	TBA TCP port number (Section 8).		TBA TCP port number (Section 8).
	skipping to change at page 5, line 7 ¶		skipping to change at page 5, line 7 ¶
	o Perform access controls according to local policies.		o Perform access controls according to local policies.
	The main advantage of network-assisted Converters is that they enable		The main advantage of network-assisted Converters is that they enable
	new TCP extensions to be used on a subset of the end-to-end path,		new TCP extensions to be used on a subset of the end-to-end path,
	which encourages the deployment of these extensions. The Transport		which encourages the deployment of these extensions. The Transport
	Converter allows the client and the server to directly negotiate TCP		Converter allows the client and the server to directly negotiate TCP
	options.		options.
	The Convert Protocol is a generic mechanism to provide 0-RTT		The Convert Protocol is a generic mechanism to provide 0-RTT
	conversion service. As a sample applicability use case, this		conversion service. As a sample applicability use case, this
	document specifies how the Convert Protocol applies for Multiptah		document specifies how the Convert Protocol applies for Multipath
	TCP. It is out of scope of this document to provide a comprehensive		TCP. It is out of scope of this document to provide a comprehensive
	list of potential all conversion services; separate documents may be		list of potential all conversion services; separate documents may be
	edited in the future for other conversion services upon need.		edited in the future for other conversion services upon need.
	This document does not assume that all the traffic is eligible to the		This document does not assume that all the traffic is eligible to the
	network-assisted conversion service. Only a subset of the traffic		network-assisted conversion service. Only a subset of the traffic
	will be forwarded to a Converter according to a set of policies.		will be forwarded to a Converter according to a set of policies.
	Furthermore, it is possible to bypass the Converter to connect to the		Furthermore, it is possible to bypass the Converter to connect to the
	servers that already support the required TCP extension.		servers that already support the required TCP extension.
	This document assumes that a client is configured with one or a list		This document assumes that a client is configured with one or a list
	of Converters. Configuration means are outside the scope of this		of Converters (e.g., [I-D.boucadair-tcpm-dhc-converter]).
	document.		Configuration means are outside the scope of this document.
	This document is organized as follows. We first provide a brief		This document is organized as follows. We first provide a brief
	explanation of the operation of Transport Converters in Section 3.		explanation of the operation of Transport Converters in Section 3.
	We describe the Converter Protocol in Section 4. We discuss in		We describe the Converter Protocol in Section 4. We discuss in
	Section 5 how Transport Converters can be used to support different		Section 5 how Transport Converters can be used to support different
	TCP options. We then discuss the interactions with middleboxes		TCP options. We then discuss the interactions with middleboxes
	(Section 6) and the security considerations (Section 7).		(Section 6) and the security considerations (Section 7).
	Appendix A provides a comparison with SOCKS proxies that are already		Appendix A provides a comparison with SOCKS proxies that are already
	used to deploy Multipath TCP in some cellular networks.		used to deploy Multipath TCP in some cellular networks.
	skipping to change at page 7, line 7 ¶		skipping to change at page 7, line 7 ¶
	Client hosts and on Transport Converters. Further, the architecture		Client hosts and on Transport Converters. Further, the architecture
	allows for making use of TCP new extensions if those are supported by		allows for making use of TCP new extensions if those are supported by
	a given server.		a given server.
	The Client is configured, through means that are outside the scope of		The Client is configured, through means that are outside the scope of
	this document, with the names and/or the addresses of one or more		this document, with the names and/or the addresses of one or more
	Transport Converters.		Transport Converters.
	The architecture does not mandate anything on the server side.		The architecture does not mandate anything on the server side.
			Similar to address sharing mechanisms, the architecture does not
			interfere with end-to-end TLS connections between the client and the
			server.
	One of the benefits of this design is that different transport		One of the benefits of this design is that different transport
	protocol extensions can be used on the upstream and the downstream		protocol extensions can be used on the upstream and the downstream
	connections. This encourages the deployment of new TCP extensions		connections. This encourages the deployment of new TCP extensions
	until they are widely supported by servers.		until they are widely supported by servers.
	3.2. Theory of Operation		3.2. Theory of Operation
	At a high level, the objective of the Transport Converter is to allow		At a high level, the objective of the Transport Converter is to allow
	the Client to use a specific extension, e.g. Multipath TCP, on a		the Client to use a specific extension, e.g. Multipath TCP, on a
	subset of the end-to-end path even if the Server does not support		subset of the end-to-end path even if the Server does not support
	skipping to change at page 13, line 46 ¶		skipping to change at page 13, line 46 ¶
	1 2 3		1 2 3
	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		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
	+---------------+---------------+-------------------------------+		+---------------+---------------+-------------------------------+
	| Type | Length | (optional) Value ... |		| Type | Length | (optional) Value ... |
	+---------------+---------------+-------------------------------+		+---------------+---------------+-------------------------------+
	| ... (optional) Value |		| ... (optional) Value |
	+---------------------------------------------------------------+		+---------------------------------------------------------------+
	Figure 10: Converter Generic TLV Format		Figure 10: Converter Generic TLV Format
	A given TLV MUST only appear once on a connection. If two or more		A given TLV LUST only appear once on a connection. If two or more
	instances of the same TLV are exchanged over a Converter connection,		copies of the same TLV are exchanged over a Converter connection, the
	the associated TCP connections MUST be closed.		associated TCP connections MUST be closed. All fields are encoded
			using the network byte order. The length field is the number of 32
			bits words.
	4.2.2. Summary of Supported Convert TLVs		4.2.2. Summary of Supported Convert TLVs
	This document specifies the following Convert TLVs:		This document specifies the following Convert TLVs:
	+------+-----+----------+------------------------------------------+		+------+-----+----------+------------------------------------------+
	| Type | Hex | Length | Description |		| Type | Hex | Length | Description |
	+------+-----+----------+------------------------------------------+		+------+-----+----------+------------------------------------------+
	| 1 | 0x1 | 1 | Bootstrap TLV |		| 1 | 0x1 | 1 | Bootstrap TLV |
	| 10 | 0xA | Variable| Connect TLV |		| 10 | 0xA | Variable| Connect TLV |
	skipping to change at page 16, line 22 ¶		skipping to change at page 16, line 22 ¶
	service, solely Kind=30 will be present in the Supported TCP		service, solely Kind=30 will be present in the Supported TCP
	Extension Services TLV returned by the Converter to a requesting		Extension Services TLV returned by the Converter to a requesting
	Client.		Client.
	4.2.5. Connect TLV		4.2.5. Connect TLV
	The Connect TLV (Figure 14) is used to request the establishment of a		The Connect TLV (Figure 14) is used to request the establishment of a
	connection via a Transport Converter.		connection via a Transport Converter.
	The 'Remote Peer Port' and 'Remote Peer IP Address' fields contain		The 'Remote Peer Port' and 'Remote Peer IP Address' fields contain
	the destination port and IP address of the target server for an		the destination port number and IP address of the target server for
	outgoing connection towards a server located on the Internet. For		an outgoing connection towards a server located on the Internet. For
	incoming connections destined to a client serviced via a Converter,		incoming connections destined to a client serviced via a Converter,
	these fields convey the source port and IP address.		these fields convey the source port and IP address.
	The Remote Peer IP Address MUST be encoded as an IPv6 address. IPv4		The Remote Peer IP Address MUST be encoded as an IPv6 address. IPv4
	addresses MUST be encoded using the IPv4-Mapped IPv6 Address format		addresses MUST be encoded using the IPv4-Mapped IPv6 Address format
	defined in [RFC4291].		defined in [RFC4291].
	The optional 'TCP Options' field is used to specify how specific TCP		The optional 'TCP Options' field is used to specify how specific TCP
	Options should be advertised by the Transport Converter to the final		Options should be advertised by the Transport Converter to the final
	destination of a connection. If this field is not supplied, the		destination of a connection. If this field is not supplied, the
	Transport Converter MUST use the default TCP options that correspond		Transport Converter MUST use the default TCP options that correspond
	to its local policy.		to its local policy.
			The Connect TLV could be designed to be generic to include the DNS
			name of the remote peer instead of its IP address as in SOCKS
			[RFC1928]. However, that design was not adopted because it induces
			both an extra load and increased delays on the Converter to handle
			and manage DNS resolution requests.
	1 2 3		1 2 3
	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		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
	+---------------+---------------+-------------------------------+		+---------------+---------------+-------------------------------+
	| Type | Length | Remote Peer Port |		| Type | Length | Remote Peer Port |
	+---------------+---------------+-------------------------------+		+---------------+---------------+-------------------------------+
	| |		| |
	| Remote Peer IP Address (128 bits) |		| Remote Peer IP Address (128 bits) |
	| |		| |
	| |		| |
	+---------------------------------------------------------------+		+---------------------------------------------------------------+
	skipping to change at page 17, line 31 ¶		skipping to change at page 17, line 47 ¶
	| TCPOpt type | TCPOpt Length | Value (opt) | .... |		| TCPOpt type | TCPOpt Length | Value (opt) | .... |
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	| .... |		| .... |
	+---------------------------------------------------------------+		+---------------------------------------------------------------+
	| ... |		| ... |
	+---------------------------------------------------------------+		+---------------------------------------------------------------+
	Figure 15: The TCP Options field		Figure 15: The TCP Options field
	If a Transport Converter receives a Connect TLV with a non-empty TCP		If a Transport Converter receives a Connect TLV with a non-empty TCP
	options field, and the Converter accets to process the request, it		options field, and the Converter acceptss to process the request, it
	SHALL present those options to the destination peer in addition to		SHALL present those options to the destination peer in addition to
	the TCP options that it would have used according to its local		the TCP options that it would have used according to its local
	policies. For the TCP options that are listed without an optional		policies. For the TCP options that are listed without an optional
	value, the Converter MUST generate its own value. For the TCP		value, the Converter MUST generate its own value. For the TCP
	options that are included in the 'TCP Options' field with an optional		options that are included in the 'TCP Options' field with an optional
	value, it SHALL copy the entire option for use in the connection with		value, it SHALL copy the entire option for use in the connection with
	the destination peer. This feature is required to support TCP Fast		the destination peer. This feature is required to support TCP Fast
	Open.		Open.
	The Converter may discard a Connect TLV request for many reasons		The Converter may discard a Connect TLV request for many reasons
	skipping to change at page 26, line 49 ¶		skipping to change at page 27, line 9 ¶
	International Mobile Subscriber Identity (IMSI) to verify that a		International Mobile Subscriber Identity (IMSI) to verify that a
	user is allowed to benefit from the aggregation service. If that		user is allowed to benefit from the aggregation service. If that
	authorization fails, the Packet Data Protocol (PDP) context/bearer		authorization fails, the Packet Data Protocol (PDP) context/bearer
	will not be mounted. This method does not require any interaction		will not be mounted. This method does not require any interaction
	with the Converter.		with the Converter.
	o The network provider may enforce a policy based upon Access		o The network provider may enforce a policy based upon Access
	Control Lists (ACLs), e.g., at a Broadband Network Gateway (BNG)		Control Lists (ACLs), e.g., at a Broadband Network Gateway (BNG)
	to control the hosts that are authorized to communicate with a		to control the hosts that are authorized to communicate with a
	Converter. These ACLs may be installed as a result of RADIUS		Converter. These ACLs may be installed as a result of RADIUS
	exchanges, e.g. [I-D.boucadair-mptcp-radius]. This method does		exchanges, e.g. [I-D.boucadair-radext-tcpm-converter]. This
	not require any interaction with the Converter.		method does not require any interaction with the Converter.
	o A device that embeds the Converter may also host a RADIUS client		o A device that embeds the Converter may also host a RADIUS client
	that will solicit an AAA server to check whether connections		that will solicit an AAA server to check whether connections
	received from a given source IP address are authorized or not		received from a given source IP address are authorized or not
	[I-D.boucadair-mptcp-radius].		[I-D.boucadair-radext-tcpm-converter].
	A first safeguard against the misuse of Converter resources by		A first safeguard against the misuse of Converter resources by
	illegitimate users (e.g., users with access networks that are not		illegitimate users (e.g., users with access networks that are not
	managed by the same provider that operates the Converter) is the		managed by the same provider that operates the Converter) is the
	Converter to reject Multipath TCP connections received on its		Converter to reject Multipath TCP connections received on its
	Internet-facing interfaces. Only Multipath PTCP connections received		Internet-facing interfaces. Only Multipath PTCP connections received
	on the customer-facing interfaces of a Converter will be accepted.		on the customer-facing interfaces of a Converter will be accepted.
	8. IANA Considerations		8. IANA Considerations
	skipping to change at page 29, line 34 ¶		skipping to change at page 29, line 38 ¶
	Figure 19: The Convert Error Codes		Figure 19: The Convert Error Codes
	9. Acknowledgements		9. Acknowledgements
	Although they could disagree with the contents of the document, we		Although they could disagree with the contents of the document, we
	would like to thank Joe Touch and Juliusz Chroboczek whose comments		would like to thank Joe Touch and Juliusz Chroboczek whose comments
	on the MPTCP mailing list have forced us to reconsider the design of		on the MPTCP mailing list have forced us to reconsider the design of
	the solution several times.		the solution several times.
	We would like to thank Raphael Bauduin, Stefano Secci, and Benjamin		We would like to thank Raphael Bauduin, Stefano Secci, Benjamin
	Hesmans for their help in preparing this document. Sri Gundavelli		Hesmans and Anandatirtha Nandugudi for their help in preparing this
	and Nandini Ganesh provided valuable feedback about the handling of		document. Nandini Ganesh provided valuable feedback about the
	TFO and the error codes. Thanks to them.		handling of TFO and the error codes. Thanks to them.
	This document builds upon earlier documents that proposed various		This document builds upon earlier documents that proposed various
	forms of Multipath TCP proxies [I-D.boucadair-mptcp-plain-mode],		forms of Multipath TCP proxies [I-D.boucadair-mptcp-plain-mode],
	[I-D.peirens-mptcp-transparent] and [HotMiddlebox13b].		[I-D.peirens-mptcp-transparent] and [HotMiddlebox13b].
	From [I-D.boucadair-mptcp-plain-mode]:		From [I-D.boucadair-mptcp-plain-mode]:
	Many thanks to Chi Dung Phung, Mingui Zhang, Rao Shoaib, Yoshifumi		Many thanks to Chi Dung Phung, Mingui Zhang, Rao Shoaib, Yoshifumi
	Nishida, and Christoph Paasch for their valuable comments.		Nishida, and Christoph Paasch for their valuable comments.
	skipping to change at page 30, line 15 ¶		skipping to change at page 30, line 19 ¶
	Special thanks to Pierrick Seite, Yannick Le Goff, Fred Klamm, and		Special thanks to Pierrick Seite, Yannick Le Goff, Fred Klamm, and
	Xavier Grall for their inputs.		Xavier Grall for their inputs.
	Thanks also to Olaf Schleusing, Martin Gysi, Thomas Zasowski, Andreas		Thanks also to Olaf Schleusing, Martin Gysi, Thomas Zasowski, Andreas
	Burkhard, Silka Simmen, Sandro Berger, Michael Melloul, Jean-Yves		Burkhard, Silka Simmen, Sandro Berger, Michael Melloul, Jean-Yves
	Flahaut, Adrien Desportes, Gregory Detal, Benjamin David, Arun		Flahaut, Adrien Desportes, Gregory Detal, Benjamin David, Arun
	Srinivasan, and Raghavendra Mallya for the discussion.		Srinivasan, and Raghavendra Mallya for the discussion.
	9.1. Contributors		9.1. Contributors
			Bart Peirens contributed to an early version of the document.
	As noted above, this document builds on two previous documents.		As noted above, this document builds on two previous documents.
	The authors of [I-D.boucadair-mptcp-plain-mode] were: - Mohamed		The authors of [I-D.boucadair-mptcp-plain-mode] were:
	Boucadair - Christian Jacquenet - Olivier Bonaventure - Denis
	Behaghel - Stefano Secci - Wim Henderickx - Robert Skog - Suresh
	Vinapamula - SungHoon Seo - Wouter Cloetens - Ullrich Meyer - Luis M.
	Contreras - Bart Peirens
	The authors of [I-D.peirens-mptcp-transparent] were: - Bart Peirens -		o Mohamed Boucadair
	Gregory Detal - Sebastien Barre - Olivier Bonaventure
			o Christian Jacquenet
			o Olivier Bonaventure
			o Denis Behaghel
			o Stefano Secci
			o Wim Henderickx
			o Robert Skog
			o Suresh Vinapamula
			o SungHoon Seo
			o Wouter Cloetens
			o Ullrich Meyer
			o Luis M. Contreras
			o Bart Peirens
			The authors of [I-D.peirens-mptcp-transparent] were:
			o Bart Peirens
			o Gregory Detal
			o Sebastien Barre
			o Olivier Bonaventure
	10. Change Log		10. Change Log
	This section to be removed before publication.		This section to be removed before publication.
	o 00 : initial version, designed to support Multipath TCP and TFO		o 00 : initial version, designed to support Multipath TCP and TFO
	only		only
	o 00 to -01 : added section Section 5 describing the support of		o 00 to -01 : added section Section 5 describing the support of
	different standard tracks TCP options by Transport Converters,		different standard tracks TCP options by Transport Converters,
	clarification of the IANA section, moved the SOCKS comparison to		clarification of the IANA section, moved the SOCKS comparison to
	the appendix and various minor modifications		the appendix and various minor modifications
			o 01 to -02 : Minor modifications
	11. References		11. References
	11.1. Normative References		11.1. Normative References
	[RFC0793] Postel, J., "Transmission Control Protocol", STD 7,		[RFC0793] Postel, J., "Transmission Control Protocol", STD 7,
	RFC 793, DOI 10.17487/RFC0793, September 1981,		RFC 793, DOI 10.17487/RFC0793, September 1981,
	<https://www.rfc-editor.org/info/rfc793>.		<https://www.rfc-editor.org/info/rfc793>.
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119,		Requirement Levels", BCP 14, RFC 2119,
	skipping to change at page 32, line 30 ¶		skipping to change at page 33, line 18 ¶
	latency-02 (work in progress), October 2017.		latency-02 (work in progress), October 2017.
	[I-D.boucadair-mptcp-plain-mode]		[I-D.boucadair-mptcp-plain-mode]
	Boucadair, M., Jacquenet, C., Bonaventure, O., Behaghel,		Boucadair, M., Jacquenet, C., Bonaventure, O., Behaghel,
	D., stefano.secci@lip6.fr, s., Henderickx, W., Skog, R.,		D., stefano.secci@lip6.fr, s., Henderickx, W., Skog, R.,
	Vinapamula, S., Seo, S., Cloetens, W., Meyer, U.,		Vinapamula, S., Seo, S., Cloetens, W., Meyer, U.,
	Contreras, L., and B. Peirens, "Extensions for Network-		Contreras, L., and B. Peirens, "Extensions for Network-
	Assisted MPTCP Deployment Models", draft-boucadair-mptcp-		Assisted MPTCP Deployment Models", draft-boucadair-mptcp-
	plain-mode-10 (work in progress), March 2017.		plain-mode-10 (work in progress), March 2017.
	[I-D.boucadair-mptcp-radius]		[I-D.boucadair-radext-tcpm-converter]
	Boucadair, M. and C. Jacquenet, "RADIUS Extensions for		Boucadair, M. and C. Jacquenet, "RADIUS Extensions for
	Network-Assisted Multipath TCP (MPTCP)", draft-boucadair-		0-RTT TCP Converters", draft-boucadair-radext-tcpm-
	mptcp-radius-05 (work in progress), October 2017.		converter-00 (work in progress), April 2018.
			[I-D.boucadair-tcpm-dhc-converter]
			Boucadair, M., Jacquenet, C., and T. Reddy, "DHCP Options
			for 0-RTT TCP Converters", draft-boucadair-tcpm-dhc-
			converter-00 (work in progress), April 2018.
	[I-D.ietf-mptcp-rfc6824bis]		[I-D.ietf-mptcp-rfc6824bis]
	Ford, A., Raiciu, C., Handley, M., Bonaventure, O., and C.		Ford, A., Raiciu, C., Handley, M., Bonaventure, O., and C.
	Paasch, "TCP Extensions for Multipath Operation with		Paasch, "TCP Extensions for Multipath Operation with
	Multiple Addresses", draft-ietf-mptcp-rfc6824bis-10 (work		Multiple Addresses", draft-ietf-mptcp-rfc6824bis-11 (work
	in progress), March 2018.		in progress), May 2018.
	[I-D.ietf-tcpinc-tcpcrypt]		[I-D.ietf-tcpinc-tcpcrypt]
	Bittau, A., Giffin, D., Handley, M., Mazieres, D., Slack,		Bittau, A., Giffin, D., Handley, M., Mazieres, D., Slack,
	Q., and E. Smith, "Cryptographic protection of TCP Streams		Q., and E. Smith, "Cryptographic protection of TCP Streams
	(tcpcrypt)", draft-ietf-tcpinc-tcpcrypt-11 (work in		(tcpcrypt)", draft-ietf-tcpinc-tcpcrypt-12 (work in
	progress), November 2017.		progress), June 2018.
	[I-D.olteanu-intarea-socks-6]		[I-D.olteanu-intarea-socks-6]
	Olteanu, V. and D. Niculescu, "SOCKS Protocol Version 6",		Olteanu, V. and D. Niculescu, "SOCKS Protocol Version 6",
	draft-olteanu-intarea-socks-6-01 (work in progress),		draft-olteanu-intarea-socks-6-02 (work in progress), March
	October 2017.		2018.
	[I-D.peirens-mptcp-transparent]		[I-D.peirens-mptcp-transparent]
	Peirens, B., Detal, G., Barre, S., and O. Bonaventure,		Peirens, B., Detal, G., Barre, S., and O. Bonaventure,
	"Link bonding with transparent Multipath TCP", draft-		"Link bonding with transparent Multipath TCP", draft-
	peirens-mptcp-transparent-00 (work in progress), July		peirens-mptcp-transparent-00 (work in progress), July
	2016.		2016.
	[IETFJ16] Bonaventure, O. and S. Seo, "Multipath TCP Deployment",		[IETFJ16] Bonaventure, O. and S. Seo, "Multipath TCP Deployment",
	IETF Journal, Fall 2016 , n.d..		IETF Journal, Fall 2016 , n.d..
	skipping to change at page 36, line 37 ¶		skipping to change at page 37, line 37 ¶
	Olivier Bonaventure (editor)		Olivier Bonaventure (editor)
	Tessares		Tessares
	Email: Olivier.Bonaventure@tessares.net		Email: Olivier.Bonaventure@tessares.net
	Mohamed Boucadair (editor)		Mohamed Boucadair (editor)
	Orange		Orange
	Email: mohamed.boucadair@orange.com		Email: mohamed.boucadair@orange.com
	Bart Peirens		Sri Gundavelli
	Proximus		Cisco
	Email: bart.peirens@proximus.com		Email: sgundave@cisco.com
	SungHoon Seo		SungHoon Seo
	Korea Telecom		Korea Telecom
	Email: sh.seo@kt.com		Email: sh.seo@kt.com
	Anandatirtha Nandugudi
	Memphis University
	Email: nndugudi@memphis.edu
End of changes. 33 change blocks.
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