draft-ietf-taps-transports-01.txt		draft-ietf-taps-transports-02.txt
	Network Working Group G. Fairhurst, Ed.		Network Working Group G. Fairhurst, Ed.
	Internet-Draft University of Aberdeen		Internet-Draft University of Aberdeen
	Intended status: Informational B. Trammell, Ed.		Intended status: Informational B. Trammell, Ed.
	Expires: June 22, 2015 M. Kuehlewind, Ed.		Expires: August 10, 2015 M. Kuehlewind, Ed.
	ETH Zurich		ETH Zurich
	December 19, 2014		February 06, 2015
	Services provided by IETF transport protocols and congestion control		Services provided by IETF transport protocols and congestion control
	mechanisms		mechanisms
	draft-ietf-taps-transports-01		draft-ietf-taps-transports-02
	Abstract		Abstract
	This document describes services provided by existing IETF protocols		This document describes services provided by existing IETF protocols
	and congestion control mechanisms. It is designed to help		and congestion control mechanisms. It is designed to help
	application and network stack programmers and to inform the work of		application and network stack programmers and to inform the work of
	the IETF TAPS Working Group.		the IETF TAPS Working Group.
	Status of This Memo		Status of This Memo
	skipping to change at page 1, line 36		skipping to change at page 1, line 36
	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 http://datatracker.ietf.org/drafts/current/.		Drafts is at http://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 June 22, 2015.		This Internet-Draft will expire on August 10, 2015.
	Copyright Notice		Copyright Notice
	Copyright (c) 2014 IETF Trust and the persons identified as the		Copyright (c) 2015 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
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://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
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	skipping to change at page 2, line 46		skipping to change at page 2, line 46
	multiple stream, because it can accept blocks of data out of order,		multiple stream, because it can accept blocks of data out of order,
	UDP-Lite provides partial integrity protection, and LEDBAT can		UDP-Lite provides partial integrity protection, and LEDBAT can
	provide low-priority "scavenger" communication.		provide low-priority "scavenger" communication.
	2. Terminology		2. Terminology
	The following terms are defined throughout this document, and in		The following terms are defined throughout this document, and in
	subsequent documents produced by TAPS describing the composition and		subsequent documents produced by TAPS describing the composition and
	decomposition of transport services.		decomposition of transport services.
	[Editor Note: The terminology below was presented at the TAPS WG		[NOTE: The terminology below was presented at the TAPS WG meeting in
	meeting in Honolulu. While the factoring of the terminology seems		Honolulu. While the factoring of the terminology seems
	uncontroversial, there may be some entities which still require names		uncontroversial, there may be some entities which still require names
	(e.g. information about the interface between the transport and lower		(e.g. information about the interface between the transport and lower
	layers which could lead to the availablity or unavailibility of		layers which could lead to the availablity or unavailibility of
	certain transport protocol features). Comments are welcome via the		certain transport protocol features). Comments are welcome via the
	TAPS mailing list.]		TAPS mailing list.]
	Transport Service Feature: a specific end-to-end feature that a		Transport Service Feature: a specific end-to-end feature that a
	transport service provides to its clients. Examples include		transport service provides to its clients. Examples include
	confidentiality, reliable delivery, ordered delivery, message-		confidentiality, reliable delivery, ordered delivery, message-
	versus-stream orientation, etc.		versus-stream orientation, etc.
	skipping to change at page 3, line 37		skipping to change at page 3, line 37
	Application: an entity that uses the transport layer for end-to-end		Application: an entity that uses the transport layer for end-to-end
	delivery data across the network (this may also be an upper layer		delivery data across the network (this may also be an upper layer
	protocol or tunnel encpasulation).		protocol or tunnel encpasulation).
	3. Existing Transport Protocols		3. Existing Transport Protocols
	This section provides a list of known IETF transport protocol and		This section provides a list of known IETF transport protocol and
	transport protocol frameworks.		transport protocol frameworks.
	[Editor Note: Contributions to the sections in the list below are		[EDITOR'S NOTE: Contributions to the subsections below are welcome]
	welcome]
	3.1. Transport Control Protocol (TCP)		3.1. Transport Control Protocol (TCP)
	TCP is an IETF standards track transport protocol. [RFC0793]		TCP is an IETF standards track transport protocol. [RFC0793]
	introduces TCP as follows: "The Transmission Control Protocol (TCP)		introduces TCP as follows: "The Transmission Control Protocol (TCP)
	is intended for use as a highly reliable host-to-host protocol		is intended for use as a highly reliable host-to-host protocol
	between hosts in packet-switched computer communication networks, and		between hosts in packet-switched computer communication networks, and
	in interconnected systems of such networks." Since its introduction,		in interconnected systems of such networks." Since its introduction,
	TCP has become the default connection-oriented, stream-based		TCP has become the default connection-oriented, stream-based
	transport protocol in the Internet. It is widely implemented by		transport protocol in the Internet. It is widely implemented by
	skipping to change at page 4, line 15		skipping to change at page 4, line 15
	3.1.1. Protocol Description		3.1.1. Protocol Description
	TCP is a connection-oriented protocol, providing a three way		TCP is a connection-oriented protocol, providing a three way
	handshake to allow a client and server to set up a connection, and		handshake to allow a client and server to set up a connection, and
	mechanisms for orderly completion and immediate teardown of a		mechanisms for orderly completion and immediate teardown of a
	connection. TCP is defined by a family of RFCs [RFC4614].		connection. TCP is defined by a family of RFCs [RFC4614].
	TCP provides multiplexing to multiple sockets on each host using port		TCP provides multiplexing to multiple sockets on each host using port
	numbers. An active TCP session is identified by its four-tuple of		numbers. An active TCP session is identified by its four-tuple of
	local and remote IP addresses and local port and remote port numbers.		local and remote IP addresses and local port and remote port numbers.
			The destination port during connection setup has a different role as
			it is often used to indicate the requested service.
	TCP partitions a continuous stream of bytes into segments, sized to		TCP partitions a continuous stream of bytes into segments, sized to
	fit in IP packets, constrained by the maximum size of lower layer		fit in IP packets. ICMP-based PathMTU discovery [RFC1191][RFC1981]
	frame. PathMTU discovery is supported. Each byte in the stream is		as well as Packetization Layer Path MTU Discovery (PMTUD) [RFC4821]
	identified by a sequence number. The sequence number is used to		are supported.
	order segments on receipt, to identify segments in acknowledgments,
	and to detect unacknowledged segments for retransmission. This is		Each byte in the stream is identified by a sequence number. The
	the basis of TCP's reliable, ordered delivery of data in a stream.		sequence number is used to order segments on receipt, to identify
	TCP Selective Acknowledgment [RFC2018] extends this mechanism by		segments in acknowledgments, and to detect unacknowledged segments
	making it possible to identify missing segments more precisely,		for retransmission. This is the basis of TCP's reliable, ordered
	reducing spurious retransmission.		delivery of data in a stream. TCP Selective Acknowledgment [RFC2018]
			extends this mechanism by making it possible to identify missing
			segments more precisely, reducing spurious retransmission.
	Receiver flow control is provided by a sliding window: limiting the		Receiver flow control is provided by a sliding window: limiting the
	amount of unacknowledged data that can be outstanding at a given		amount of unacknowledged data that can be outstanding at a given
	time. The window scale option [RFC7323] allows a receiver to use		time. The window scale option [RFC7323] allows a receiver to use
	windows greater than 64KB.		windows greater than 64KB.
	All TCP senders provide Congestion Control: This uses a separate		All TCP senders provide Congestion Control: This uses a separate
	window, where each time congestion is detected, this congestion		window, where each time congestion is detected, this congestion
	window is reduced. A receiver detects congestion using one of three		window is reduced. A receiver detects congestion using one of three
	mechanisms: A retransmission timer, loss (interpreted as a congestion		mechanisms: A retransmission timer, detection of loss (interpreted as
	signal), and Explicit Congestion Notification (ECN) [RFC3168] to		a congestion signal), or Explicit Congestion Notification (ECN)
	provide early signaling (see [I-D.ietf-aqm-ecn-benefits])		[RFC3168] to provide early signaling (see
			[I-D.ietf-aqm-ecn-benefits])
	A TCP protocol instance can be extended [RFC4614] and tuned. Some		A TCP protocol instance can be extended [RFC4614] and tuned. Some
	features are sender-side only, requiring no negotiation with the		features are sender-side only, requiring no negotiation with the
	receiver; some are receiver-side only, some are explicitly negotiated		receiver; some are receiver-side only, some are explicitly negotiated
	during connection setup.		during connection setup.
	By default, TCP segment partitioning uses Nagle's algorithm [RFC0896]		By default, TCP segment partitioning uses Nagle's algorithm [RFC0896]
	to buffer data at the sender into large segments, potentially		to buffer data at the sender into large segments, potentially
	incurring sender-side buffering delay; this algorithm can be disabled		incurring sender-side buffering delay; this algorithm can be disabled
	by the sender to transmit more immediately, e.g. to enable smoother		by the sender to transmit more immediately, e.g. to enable smoother
	interactive sessions.		interactive sessions.
			[EDITOR'S NOTE: add URGENT and PUSH flag (note [RFC6093] says SHOULD
			NOT use due to the range of TCP implementations that process TCP
			urgent indications differently.) ]
			A checksum provides an Integrity Check and is mandatory across the
			entire packet. The TCP checksum does not support partial corruption
			protection as in DCCP/UDP-Lite). This check protects from
			misdelivery of data corrupted data, but is relatively weak, and
			applications that require end to end integrity of data are
			recommended to include a stronger integrity check of their payload
			data.
	A TCP service is unicast.		A TCP service is unicast.
	3.1.2. Interface description		3.1.2. Interface description
	A TCP API is defined in [REF], but there is currently no API		A User/TCP Interface is defined in [RFC0793] providing six user
	specified in the RFC series.		commands: Open, Send, Receive, Close, Status. This interface does
			not describe configuration of TCP options or parameters beside use of
			the PUSH and URGENT flags.
	In API implementations derived from the BSD Sockets API, TCP sockets		In API implementations derived from the BSD Sockets API, TCP sockets
	are created using the "SOCK_STREAM" socket type.		are created using the "SOCK_STREAM" socket type.
	The features used by a protocol instance may be set and tuned via		The features used by a protocol instance may be set and tuned via
	this API.		this API.
	(more on the API goes here)		(more on the API goes here)
	3.1.3. Transport Protocol Components		3.1.3. Transport Protocol Components
	The transport protocol components provided by TCP are:		The transport protocol components provided by TCP are:
	o unicast		o unicast
	o connection-oriented setup with feature negotiation		o connection setup with feature negotiation and application-to-port
			mapping
	o port multiplexing		o port multiplexing
	o reliable delivery		o reliable delivery
	o ordered delivery		o ordered delivery for each byte stream
	o segmented, stream-oriented delivery in a single stream		o error detection (checksum)
			o segmentation
			o stream-oriented delivery in a single stream
			o data bundling (Nagle's algorithm)
			o flow control
	o congestion control		o congestion control
	(discussion of how to map this to features and TAPS: what does the		[EDITOR'S NOTE: discussion of how to map this to features and TAPS:
	higher layer need to decide? what can the transport layer decide		what does the higher layer need to decide? what can the transport
	based on global settings? what must the transport layer decide based		layer decide based on global settings? what must the transport layer
	on network characteristics?)		decide based on network characteristics?]
	3.2. Multipath TCP (MP-TCP)		3.2. Multipath TCP (MP-TCP)
	[Editor Note: a few sentences describing Multipath TCP [RFC6824] go		[EDITOR'S NOTE: a few sentences describing Multipath TCP [RFC6824] go
	here. Note that this adds transport-layer multihoming to the		here. Note that this adds transport-layer multihoming to the
	components TCP provides]		components TCP provides]
	3.3. Stream Control Transmission Protocol (SCTP)		3.3. Stream Control Transmission Protocol (SCTP)
	SCTP [RFC4960] is an IETF standards track transport protocol that		SCTP [RFC4960] is an IETF standards track transport protocol that
	provides a bidirectional s set of logical unicast meessage streams		provides a bidirectional set of logical unicast meessage streams over
	over a connection-oriented protocol. The protocol and API use		a connection-oriented protocol.
	messages, rather than a byte-stream. Each stream of messages is		Compared to TCP, this protocol and API use messages, rather than a
	independently managed, therefore retransmission does not hold back		byte-stream. Each stream of messages is independently managed,
	data sent using other logical streams.		therefore retransmission does not hold back data sent using other
			logical streams.
			An SCTP Integrity Check is mandatory across the entire packet (it
			does not support partial corruption protection as in DCCP/UD-Lite).
	The SCTP Partial Reliability Extension (SCTP-PR) is defined in		The SCTP Partial Reliability Extension (SCTP-PR) is defined in
	[RFC3758].		[RFC3758].
			SCTP supports PLPMTU discovery using padding chunks to construct path
			probes.
	[EDITOR'S NOTE: Michael Tuexen and Karen Nielsen signed up as		[EDITOR'S NOTE: Michael Tuexen and Karen Nielsen signed up as
	contributors for these sections.]		contributors for these sections.]
	3.3.1. Protocol Description		3.3.1. Protocol Description
	An SCTP service is unicast.		An SCTP service is unicast.
			PLPMTUD is required for SCTP.
	3.3.2. Interface Description		3.3.2. Interface Description
	The SCTP API is described in the specifications published in the RFC		The SCTP API is described in the specifications published in the RFC
	series.		series.
	3.3.3. Transport Protocol Components		3.3.3. Transport Protocol Components
	The transport protocol components provided by SCTP are:		The transport protocol components provided by SCTP are:
	o unicast		o unicast
	o connection-oriented setup with feature negotiation		o connection setup with feature negotiation and application-to-port
			mapping
	o port multiplexing		o port multiplexing
	o reliable or partially reliable delivery		o reliable or partially reliable delivery
	o ordered delivery within a stream		o ordered delivery within a stream
	o support for multiple prioritised streams		o support for multiple prioritised streams
			o flow control (slow receiver function)
	o message-oriented delivery		o message-oriented delivery
	o congestion control		o congestion control
	[EDITOR'S NOTE: Please update list.]		o application PDU bundling
			o integrity check
			[EDITOR'S NOTE: update this list.]
	3.4. User Datagram Protocol (UDP)		3.4. User Datagram Protocol (UDP)
	The User Datagram Protocol (UDP) [RFC0768] [RFC2460] is an IETF		The User Datagram Protocol (UDP) [RFC0768] [RFC2460] is an IETF
	standards track transport protocol. It provides a uni-directional		standards track transport protocol. It provides a uni-directional
	minimal message-passing transport that has no inherent congestion		minimal message-passing transport that has no inherent congestion
	control mechanisms or other transport functions. IETF guidance on		control mechanisms or other transport functions. IETF guidance on
	the use of UDP is provided in [RFC5405]. UDP is widely implemented		the use of UDP is provided in [RFC5405]. UDP is widely implemented
	by endpoints and widely used by common applications.		by endpoints and widely used by common applications.
	skipping to change at page 7, line 20		skipping to change at page 8, line 17
	UDP is a connection-less datagram protocol, with no connection setup		UDP is a connection-less datagram protocol, with no connection setup
	or feature negotiation. The protocol and API use messages, rather		or feature negotiation. The protocol and API use messages, rather
	than a byte-stream. Each stream of messages is independently		than a byte-stream. Each stream of messages is independently
	managed, therefore retransmission does not hold back data sent using		managed, therefore retransmission does not hold back data sent using
	other logical streams.		other logical streams.
	It provides multiplexing to multiple sockets on each host using port		It provides multiplexing to multiple sockets on each host using port
	numbers. An active UDP session is identified by its four-tuple of		numbers. An active UDP session is identified by its four-tuple of
	local and remote IP addresses and local port and remote port numbers.		local and remote IP addresses and local port and remote port numbers.
	UDP fragments packets into IP packets, constrained by the maximum		UDP maps each data segement into an IP packet, or a sequence of IP
	size of lower layer frame.		fragemnts.
	Mechanisms for receiver flow control, congestion control, PathMTU		UDP is connectionless. However, applications send a sequence of
	discovery, support for ECN, etc need to be provided by upper layer		messages that constitute a UDP flow. Therefore mechanisms for
	protocols [RFC5405].		receiver flow control, congestion control, PathMTU discovery/PLPMTUD,
			support for ECN, etc need to be provided by upper layer protocols
			[RFC5405].
			PMTU discovery and PLPMTU discovery may be used by upper layer
			protocols built on top of UDP [RFC5405].
	For IPv4 the UDP checksum is optional, but recommended for use in the		For IPv4 the UDP checksum is optional, but recommended for use in the
	general Internet [RFC5405]. [RFC2460] requires the use of this		general Internet [RFC5405]. [RFC2460] requires the use of this
	checksum for IPv6, but [RFC6935] permits this to be relaxed for		checksum for IPv6, but [RFC6935] permits this to be relaxed for
	specific types of application. The checksum support considerations		specific types of application. The checksum support considerations
	for omitting the checksum are defined in [RFC6936].		for omitting the checksum are defined in [RFC6936].
			This check protects from misdelivery of data corrupted data, but is
			relatively weak, and applications that require end to end integrity
			of data are recommended to include a stronger integrity check of
			their payload data.
	A UDP service may support IPv4 broadcast, multicast, anycast and		A UDP service may support IPv4 broadcast, multicast, anycast and
	unicast.		unicast, determined by the IP destination address.
	3.4.2. Interface Description		3.4.2. Interface Description
	There is no current API specified in the RFC Series, but guidance on		[RFC0768] describes basic requirements for an API for UDP. Guidance
	use of common APIs is provided in [RFC5405].		on use of common APIs is provided in [RFC5405].
			Many operating systems also allow a UDP socket to be connected, i.e.,
			to bind a UDP socket to a specific pair of addresses and ports. This
			is similar to the corresponding TCP sockets API functionality.
			However, for UDP, this is only a local operation that serves to
			simplify the local send/receive functions and to filter the traffic
			for the specified addresses and ports [RFC5405].
	3.4.3. Transport Protocol Components		3.4.3. Transport Protocol Components
	The transport protocol components provided by UDP are:		The transport protocol components provided by UDP are:
	o unicast		o unicast
			o port multiplexing
	o IPv4 broadcast, multicast and anycast		o IPv4 broadcast, multicast and anycast
	o non-reliable, non-ordered delivery		o non-reliable delivery
			o flow control (slow receiver function)
			o non-ordered delivery
	o message-oriented delivery		o message-oriented delivery
	o optional checksum protection.		o optional checksum protection.
	3.5. Lightweight User Datagram Protocol (UDP-Lite)		3.5. Lightweight User Datagram Protocol (UDP-Lite)
	The Lightweight User Datagram Protocol (UDP-Lite) [RFC3828] is an		The Lightweight User Datagram Protocol (UDP-Lite) [RFC3828] is an
	IETF standards track transport protocol. UDP-Lite provides a		IETF standards track transport protocol. UDP-Lite provides a
	bidirectional set of logical unicast or multicast message streams		bidirectional set of logical unicast or multicast message streams
	over a datagram protocol. IETF guidance on the use of UDP-Lite is		over a datagram protocol. IETF guidance on the use of UDP-Lite is
	provided in [RFC5405].		provided in [RFC5405].
	skipping to change at page 8, line 20		skipping to change at page 9, line 41
	bidirectional set of logical unicast or multicast message streams		bidirectional set of logical unicast or multicast message streams
	over a datagram protocol. IETF guidance on the use of UDP-Lite is		over a datagram protocol. IETF guidance on the use of UDP-Lite is
	provided in [RFC5405].		provided in [RFC5405].
	[EDITOR'S NOTE: Gorry Fairhurst signed up as a contributor for this		[EDITOR'S NOTE: Gorry Fairhurst signed up as a contributor for this
	section.]		section.]
	3.5.1. Protocol Description		3.5.1. Protocol Description
	UDP-Lite is a connection-less datagram protocol, with no connection		UDP-Lite is a connection-less datagram protocol, with no connection
	setup or feature negotiation. The protocol and API use messages,		setup or feature negotiation. The protocol use messages, rather than
	rather than a byte-stream. Each stream of messages is independently		a byte-stream. Each stream of messages is independently managed,
	managed, therefore retransmission does not hold back data sent using		therefore retransmission does not hold back data sent using other
	other logical streams.		logical streams.
	It provides multiplexing to multiple sockets on each host using port		It provides multiplexing to multiple sockets on each host using port
	numbers. An active UDP-Lite session is identified by its four-tuple		numbers. An active UDP-Lite session is identified by its four-tuple
	of local and remote IP addresses and local port and remote port		of local and remote IP addresses and local port and remote port
	numbers.		numbers.
	UDP-Lite fragments packets into IP packets, constrained by the		UDP-Lite fragments packets into IP packets, constrained by the
	maximum size of lower layer frame.		maximum size of IP packet.
	UDP-Lite changes the semantics of the UDP "payload length" field to		UDP-Lite changes the semantics of the UDP "payload length" field to
	that of a "checksum coverage length" field. Otherwise, UDP-Lite is		that of a "checksum coverage length" field. Otherwise, UDP-Lite is
	semantically identical to UDP. Applications using UDP-Lite therefore		semantically identical to UDP. Applications using UDP-Lite therefore
	can not make assumptions regarding the correctness of the data		can not make assumptions regarding the correctness of the data
	received in the insensitive part of the UDP-Lite payload.		received in the insensitive part of the UDP-Lite payload.
	As for UDP, mechanisms for receiver flow control, congestion control,		As for UDP, mechanisms for receiver flow control, congestion control,
	PathMTU discovery, support for ECN, etc need to be provided by upper		PMTU or PLPMTU discovery, support for ECN, etc need to be provided by
	layer protocols [RFC5405].		upper layer protocols [RFC5405].
	Examples of use include a class of applications that can derive		Examples of use include a class of applications that can derive
	benefit from having partially-damaged payloads delivered, rather than		benefit from having partially-damaged payloads delivered, rather than
	discarded. One use is to support are tolerate payload corruption and		discarded. One use is to support error tolerate payload corruption
	over paths that include error-prone links, another application is		when used over paths that include error-prone links, another
	when header integrity checks are required but payload integrity is		application is when header integrity checks are required, but payload
	provided by some other mechanism (e.g. [RFC6936].		integrity is provided by some other mechanism (e.g. [RFC6936].
	A UDP-Lite service may support IPv4 broadcast, multicast, anycast and		A UDP-Lite service may support IPv4 broadcast, multicast, anycast and
	unicast.		unicast.
	3.5.2. Interface Description		3.5.2. Interface Description
	There is no current API specified in the RFC Series, but guidance on		There is no current API specified in the RFC Series, but guidance on
	use of common APIs is provided in [RFC5405].		use of common APIs is provided in [RFC5405].
	The interface of UDP-Lite differs from that of UDP by the addition of		The interface of UDP-Lite differs from that of UDP by the addition of
	skipping to change at page 9, line 25		skipping to change at page 10, line 48
	the application via the UDP-Lite MIB module [RFC5097].		the application via the UDP-Lite MIB module [RFC5097].
	3.5.3. Transport Protocol Components		3.5.3. Transport Protocol Components
	The transport protocol components provided by UDP-Lite are:		The transport protocol components provided by UDP-Lite are:
	o unicast		o unicast
	o IPv4 broadcast, multicast and anycast		o IPv4 broadcast, multicast and anycast
			o port multiplexing
	o non-reliable, non-ordered delivery		o non-reliable, non-ordered delivery
	o message-oriented delivery		o message-oriented delivery
	o partial integrity protection		o partial integrity protection
	3.6. Datagram Congestion Control Protocol (DCCP)		3.6. Datagram Congestion Control Protocol (DCCP)
	Datagram Congestion Control Protocol (DCCP) [RFC4340] is an IETF		Datagram Congestion Control Protocol (DCCP) [RFC4340] is an IETF
	standards track bidirectional transport protocol that provides		standards track bidirectional transport protocol that provides
	unicast connections of congestion-controlled unreliable messages.		unicast connections of congestion-controlled unreliable messages.
	DCCP is suitable for applications that transfer fairly large amounts
	of data and that can benefit from control over the trade off between
	timeliness and reliability [RFC4336].
	[EDITOR'S NOTE: Gorry Fairhurst signed up as a contributor for this		[EDITOR'S NOTE: Gorry Fairhurst signed up as a contributor for this
	section.]		section.]
			The DCCP Problem Statement describes the goals that DCCP sought to
			address [RFC4336]. It is suitable for applications that transfer
			fairly large amounts of data and that can benefit from control over
			the trade off between timeliness and reliability [RFC4336].
			It offers low overhead, and many characteristics common to UDP, but
			can avoid "Re-inventing the wheel" each time a new multimedia
			application emerges. Specifically it includes core functions
			(feature negotiation, path state management, RTT calculation, PMTUD,
			etc): This allows applications to use a compatible method defining
			how they send packets and where suitable to choose common algorithms
			to manage their functions. Examples of suitable applications include
			interactive applications, streaming media or on-line games [RFC4336].
	3.6.1. Protocol Description		3.6.1. Protocol Description
	DCCP is a connection-oriented datagram protocol, providing a three		DCCP is a connection-oriented datagram protocol, providing a three
	way handshake to allow a client and server to set up a connection,		way handshake to allow a client and server to set up a connection,
	and mechanisms for orderly completion and immediate teardown of a		and mechanisms for orderly completion and immediate teardown of a
	connection. The protocol is defined by a family of RFCs.		connection. The protocol is defined by a family of RFCs.
	It provides multiplexing to multiple sockets on each host using port		It provides multiplexing to multiple sockets on each host using port
	numbers. An active DCCP session is identified by its four-tuple of		numbers. An active DCCP session is identified by its four-tuple of
	local and remote IP addresses and local port and remote port numbers.		local and remote IP addresses and local port and remote port numbers.
	skipping to change at page 10, line 4		skipping to change at page 11, line 39
	3.6.1. Protocol Description		3.6.1. Protocol Description
	DCCP is a connection-oriented datagram protocol, providing a three		DCCP is a connection-oriented datagram protocol, providing a three
	way handshake to allow a client and server to set up a connection,		way handshake to allow a client and server to set up a connection,
	and mechanisms for orderly completion and immediate teardown of a		and mechanisms for orderly completion and immediate teardown of a
	connection. The protocol is defined by a family of RFCs.		connection. The protocol is defined by a family of RFCs.
	It provides multiplexing to multiple sockets on each host using port		It provides multiplexing to multiple sockets on each host using port
	numbers. An active DCCP session is identified by its four-tuple of		numbers. An active DCCP session is identified by its four-tuple of
	local and remote IP addresses and local port and remote port numbers.		local and remote IP addresses and local port and remote port numbers.
	At connection setup, DCCP also exchanges the the service code		At connection setup, DCCP also exchanges the the service code
	[RFC5595] mechanism to allow transport instantiations to indicate the		[RFC5595] mechanism to allow transport instantiations to indicate the
	service treatment that is expected from the network.		service treatment that is expected from the network.
	The protocol segments data into messages, sized to fit in IP packets,		The protocol segments data into messages, typically sized to fit in
	constrained by the maximum size of lower layer frame. Each message		IP packets, but which may be fragemented providing they are less than
	is identified by a sequence number. The sequence number is used to		the A DCCP interface MAY allow applications to request fragmentation
	identify segments in acknowledgments, to detect unacknowledged		for packets larger than PMTU, but not larger than the maximum packet
	segments, to measure RTT, etc. The protocol may support ordered or		size allowed by the current congestion control mechanism (CCMPS)
	unordered delivery of data, and does not itself provide		[RFC4340].
	retransmission.
			Each message is identified by a sequence number. The sequence number
			is used to identify segments in acknowledgments, to detect
			unacknowledged segments, to measure RTT, etc. The protocol may
			support ordered or unordered delivery of data, and does not itself
			provide retransmission. There is a Data Checksum option, which
			contains a strong CRC, lets endpoints detect application data
			corruption. It also supports reduced checksum coverage, a partial
			integrity mechanisms similar to UDP-lIte.
	Receiver flow control is supported: limiting the amount of		Receiver flow control is supported: limiting the amount of
	unacknowledged data that can be outstanding at a given time.		unacknowledged data that can be outstanding at a given time.
	A DCCP protocol instance can be extended [RFC4340] and tuned. Some		A DCCP protocol instance can be extended [RFC4340] and tuned. Some
	features are sender-side only, requiring no negotiation with the		features are sender-side only, requiring no negotiation with the
	receiver; some are receiver-side only, some are explicitly negotiated		receiver; some are receiver-side only, some are explicitly negotiated
	during connection setup.		during connection setup.
	DCCP supports negotiation of the congestion control profile, examples		DCCP supports negotiation of the congestion control profile, to
	of specified profiles include [RFC4341] [RFC4342] [RFC5662]. All		provide Plug and Play congestion control mechanisms. examples of
	IETF-defined methods provide Congestion Control.		specified profiles include [RFC4341] [RFC4342] [RFC5662]. All IETF-
			defined methods provide Congestion Control.
	Examples of suitable applications include interactive applications,		DCCP use a Connect packet to start a session, and permits half-
	streaming media or on-line games [RFC4336].		connections that allow each client to choose features it wishes to
			support. Simultaneous open [RFC5596], as in TCP, can enable
			interoperability in the presence of middleboxes. The Connect packet
			includes a Service Code field [RFC5595] designed to allow middle
			boxes and endpoints to identify the characteristics required by a
			session. A lightweight UDP-based encapsulation (DCCP-UDP) has been
			defined [RFC6773] that permits DCCP to be used over paths where it is
			not natively supported. Support in NAPT/NATs is defined in [RFC4340]
			and [RFC5595].
			Upper layer protocols specified on top of DCCP include: DTLS
			[RFC5595], RTP [RFC5672], ICE/SDP [RFC6773].
	A DCCP service is unicast.		A DCCP service is unicast.
			A common packet format has allowed tools to evolve that can read and
			interpret DCCP packets (e.g. Wireshark).
	3.6.2. Interface Description		3.6.2. Interface Description
			API charactersitics include: - Datagram transmission. - Notification
			of the current maximum packet size. - Send and reception of zero-
			length payloads. - Set the Slow Receiver flow control at areceiver.
			- Detct a Slow receiver at the sender.
	There is no current API specified in the RFC Series.		There is no current API specified in the RFC Series.
	3.6.3. Transport Protocol Components		3.6.3. Transport Protocol Components
	The transport protocol components provided by DCCP are:		The transport protocol components provided by DCCP are:
	o unicast		o unicast
	o connection-oriented setup		o connection setup with feature negotiation and application-to-port
			mapping
	o feature negotiation		o Service Codes
			o port multiplexing
	o non-reliable, ordered delivery		o non-reliable, ordered delivery
			o flow control (slow receiver function)
			o drop notification
			o timestamps
	o message-oriented delivery		o message-oriented delivery
	o partial integrity protection		o partial integrity protection
	3.7. Realtime Transport Protocol (RTP)		3.7. Realtime Transport Protocol (RTP)
	RTP provides an end-to-end network transport service, suitable for		RTP provides an end-to-end network transport service, suitable for
	applications transmitting real-time data, such as audio, video or		applications transmitting real-time data, such as audio, video or
	data, over multicast or unicast network services, including TCP, UDP,		data, over multicast or unicast network services, including TCP, UDP,
	UDP-Lite, DCCP.		UDP-Lite, DCCP.
	[EDITOR'S NOTE: Varun Singh signed up as contributor for this		[EDITOR'S NOTE: Varun Singh signed up as contributor for this
	section.]		section.]
	3.8. Transport Layer Security (TLS) and Datagram TLS (DTLS) as a		3.8. Transport Layer Security (TLS) and Datagram TLS (DTLS) as a
	pseudotransport		pseudo transport
	(A few words on TLS [RFC5246] and DTLS [RFC6347] here, and how they		[NOTE: A few words on TLS [RFC5246] and DTLS [RFC6347] here, and how
	get used by other protocols to meet security goals as an add-on		they get used by other protocols to meet security goals as an add-on
	interlayer above transport.)		interlayer above transport.]
	3.8.1. Protocol Description		3.8.1. Protocol Description
	3.8.2. Interface Description		3.8.2. Interface Description
	3.8.3. Transport Protocol Components		3.8.3. Transport Protocol Components
	3.9. Hypertext Transport Protocol (HTTP) as a pseudotransport		3.9. Hypertext Transport Protocol (HTTP) as a pseudotransport
	[RFC3205]		[RFC3205]
			[EDITOR'S NOTE: No identified contributor for this section yet.]
	3.9.1. Protocol Description		3.9.1. Protocol Description
	3.9.2. Interface Description		3.9.2. Interface Description
	3.9.3. Transport Protocol Components		3.9.3. Transport Protocol Components
	3.10. WebSockets		3.10. WebSockets
	[RFC6455]		[RFC6455]
			[EDITOR'S NOTE: No identified contributor for this section yet.]
	3.10.1. Protocol Description		3.10.1. Protocol Description
	3.10.2. Interface Description		3.10.2. Interface Description
	3.10.3. Transport Protocol Components		3.10.3. Transport Protocol Components
	4. Transport Service Features		4. Transport Service Features
	(drawn from the candidate features provided by protocol components in		[EDITOR'S NOTE: this section will drawn from the candidate features
	the previous section - please discussion on list)		provided by protocol components in the previous section - please
			discuss on taps@ietf.org list]
	4.1. Complete Protocol Feature Matrix		4.1. Complete Protocol Feature Matrix
	(a comprehensive matrix table goes here; Volunteer: Dave Thaler)		[EDITOR'S NOTE: Dave Thaler has signed up as a contributor for this
			section. Michael Welzl also has a beginning of a matrix which could
			be useful here.]
			[EDITOR'S NOTE: The below is a strawman proposal below by Gorry
			Fairhurst for initial discussion]
			The table below summarises protocol mechanisms that have been
			standardised. It does not make an assessment on whether specific
			implementations are fully compliant to these specifications.
			+-----------------+---------+---------+---------+---------+---------+
			| Mechanism | UDP | UDP-L | DCCP | SCTP | TCP |
			+-----------------+---------+---------+---------+---------+---------+
			| Unicast | Yes | Yes | Yes | Yes | Yes |
			| | | | | | |
			| Mcast/IPv4Bcast | Yes(2) | Yes | No | No | No |
			| | | | | | |
			| Port Mux | Yes | Yes | Yes | Yes | Yes |
			| | | | | | |
			| Mode | Dgram | Dgram | Dgram | Stream | Stream |
			| | | | | | |
			| Connected | No | No | Yes | Yes | Yes |
			| | | | | | |
			| Data bundling | No | No | No | No | Yes |
			| | | | | | |
			| Feature Nego | No | No | Yes | Yes | Yes |
			| | | | | | |
			| Options | No | No | Support | Support | Support |
			| | | | | | |
			| Data priority | * | * | * | Yes | No |
			| | | | | | |
			| Data bundling | No | No | No | No | Yes |
			| | | | | | |
			| Reliability | None | None | None | Select | Full |
			| | | | | | |
			| Ordered deliv | No | No | No | Stream | Yes |
			| | | | | | |
			| Corruption Tol. | No | Support | Support | No | No |
			| | | | | | |
			| Flow Control | No | No | Support | Yes | Yes |
			| | | | | | |
			| PMTU/PLPMTU | (1) | (1) | Yes | Yes | Yes |
			| | | | | | |
			| Cong Control | (1) | (1) | Yes | Yes | Yes |
			| | | | | | |
			| ECN Support | (1) | (1) | Yes | No | Yes |
			| | | | | | |
			| NAT support | Limited | Limited | Support | TBD | Support |
			| | | | | | |
			| Security | DTLS | DTLS | DTLS | DTLS | TLS, AO |
			| | | | | | |
			| UDP encaps | N/A | None | Yes | Yes | None |
			| | | | | | |
			| RTP support | Support | Support | Support | ? | Support |
			+-----------------+---------+---------+---------+---------+---------+
			Note (1): this feature requires support in an upper layer protocol.
			Note (2): this feature requires support in an upper layer protocol
			when used with IPv6.
	5. IANA Considerations		5. IANA Considerations
	This document has no considerations for IANA.		This document has no considerations for IANA.
	6. Security Considerations		6. Security Considerations
	This document surveys existing transport protocols and protocols		This document surveys existing transport protocols and protocols
	providing transport-like services. Confidentiality, integrity, and		providing transport-like services. Confidentiality, integrity, and
	authenticity are among the features provided by those services. This		authenticity are among the features provided by those services. This
	document does not specify any new components or mechanisms for		document does not specify any new components or mechanisms for
	providing these features. Each RFC listed in this document discusses		providing these features. Each RFC listed in this document discusses
	the security considerations of the specification it contains.		the security considerations of the specification it contains.
	7. Contributors		7. Contributors
	Non-editor contributors of text will be listed here, as in the		[EDITOR'S NOTE: Non-editor contributors of text will be listed here,
	authors section.		as noted in the authors section.]
	8. Acknowledgments		8. Acknowledgments
	This work is partially supported by the European Commission under		This work is partially supported by the European Commission under
	grant agreement FP7-ICT-318627 mPlane; support does not imply		grant agreement FP7-ICT-318627 mPlane; support does not imply
	endorsement.		endorsement.
	9. References		9. References
	9.1. Normative References		9.1. Normative References
	skipping to change at page 13, line 11		skipping to change at page 17, line 5
	[RFC0793] Postel, J., "Transmission Control Protocol", STD 7, RFC		[RFC0793] Postel, J., "Transmission Control Protocol", STD 7, RFC
	793, September 1981.		793, September 1981.
	[RFC0896] Nagle, J., "Congestion control in IP/TCP internetworks",		[RFC0896] Nagle, J., "Congestion control in IP/TCP internetworks",
	RFC 896, January 1984.		RFC 896, January 1984.
	[RFC1122] Braden, R., "Requirements for Internet Hosts -		[RFC1122] Braden, R., "Requirements for Internet Hosts -
	Communication Layers", STD 3, RFC 1122, October 1989.		Communication Layers", STD 3, RFC 1122, October 1989.
			[RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191,
			November 1990.
			[RFC1981] McCann, J., Deering, S., and J. Mogul, "Path MTU Discovery
			for IP version 6", RFC 1981, August 1996.
	[RFC2018] Mathis, M., Mahdavi, J., Floyd, S., and A. Romanow, "TCP		[RFC2018] Mathis, M., Mahdavi, J., Floyd, S., and A. Romanow, "TCP
	Selective Acknowledgment Options", RFC 2018, October 1996.		Selective Acknowledgment Options", RFC 2018, October 1996.
	[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6		[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
	(IPv6) Specification", RFC 2460, December 1998.		(IPv6) Specification", RFC 2460, December 1998.
	[RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition		[RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition
	of Explicit Congestion Notification (ECN) to IP", RFC		of Explicit Congestion Notification (ECN) to IP", RFC
	3168, September 2001.		3168, September 2001.
	skipping to change at page 14, line 9		skipping to change at page 18, line 9
	[RFC4342] Floyd, S., Kohler, E., and J. Padhye, "Profile for		[RFC4342] Floyd, S., Kohler, E., and J. Padhye, "Profile for
	Datagram Congestion Control Protocol (DCCP) Congestion		Datagram Congestion Control Protocol (DCCP) Congestion
	Control ID 3: TCP-Friendly Rate Control (TFRC)", RFC 4342,		Control ID 3: TCP-Friendly Rate Control (TFRC)", RFC 4342,
	March 2006.		March 2006.
	[RFC4614] Duke, M., Braden, R., Eddy, W., and E. Blanton, "A Roadmap		[RFC4614] Duke, M., Braden, R., Eddy, W., and E. Blanton, "A Roadmap
	for Transmission Control Protocol (TCP) Specification		for Transmission Control Protocol (TCP) Specification
	Documents", RFC 4614, September 2006.		Documents", RFC 4614, September 2006.
			[RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU
			Discovery", RFC 4821, March 2007.
	[RFC4960] Stewart, R., "Stream Control Transmission Protocol", RFC		[RFC4960] Stewart, R., "Stream Control Transmission Protocol", RFC
	4960, September 2007.		4960, September 2007.
	[RFC5097] Renker, G. and G. Fairhurst, "MIB for the UDP-Lite		[RFC5097] Renker, G. and G. Fairhurst, "MIB for the UDP-Lite
	protocol", RFC 5097, January 2008.		protocol", RFC 5097, January 2008.
	[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security		[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
	(TLS) Protocol Version 1.2", RFC 5246, August 2008.		(TLS) Protocol Version 1.2", RFC 5246, August 2008.
	[RFC5348] Floyd, S., Handley, M., Padhye, J., and J. Widmer, "TCP		[RFC5348] Floyd, S., Handley, M., Padhye, J., and J. Widmer, "TCP
	Friendly Rate Control (TFRC): Protocol Specification", RFC		Friendly Rate Control (TFRC): Protocol Specification", RFC
	5348, September 2008.		5348, September 2008.
	[RFC5405] Eggert, L. and G. Fairhurst, "Unicast UDP Usage Guidelines		[RFC5405] Eggert, L. and G. Fairhurst, "Unicast UDP Usage Guidelines
	for Application Designers", BCP 145, RFC 5405, November		for Application Designers", BCP 145, RFC 5405, November
	2008.		2008.
	[RFC5595] Fairhurst, G., "The Datagram Congestion Control Protocol		[RFC5595] Fairhurst, G., "The Datagram Congestion Control Protocol
	(DCCP) Service Codes", RFC 5595, September 2009.		(DCCP) Service Codes", RFC 5595, September 2009.
			[RFC5596] Fairhurst, G., "Datagram Congestion Control Protocol
			(DCCP) Simultaneous-Open Technique to Facilitate NAT/
			Middlebox Traversal", RFC 5596, September 2009.
	[RFC5662] Shepler, S., Eisler, M., and D. Noveck, "Network File		[RFC5662] Shepler, S., Eisler, M., and D. Noveck, "Network File
	System (NFS) Version 4 Minor Version 1 External Data		System (NFS) Version 4 Minor Version 1 External Data
	Representation Standard (XDR) Description", RFC 5662,		Representation Standard (XDR) Description", RFC 5662,
	January 2010.		January 2010.
			[RFC5672] Crocker, D., "RFC 4871 DomainKeys Identified Mail (DKIM)
			Signatures -- Update", RFC 5672, August 2009.
			[RFC6773] Phelan, T., Fairhurst, G., and C. Perkins, "DCCP-UDP: A
			Datagram Congestion Control Protocol UDP Encapsulation for
			NAT Traversal", RFC 6773, November 2012.
	[RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP		[RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP
	Authentication Option", RFC 5925, June 2010.		Authentication Option", RFC 5925, June 2010.
	[RFC5681] Allman, M., Paxson, V., and E. Blanton, "TCP Congestion		[RFC5681] Allman, M., Paxson, V., and E. Blanton, "TCP Congestion
	Control", RFC 5681, September 2009.		Control", RFC 5681, September 2009.
	[RFC6093] Gont, F. and A. Yourtchenko, "On the Implementation of the		[RFC6093] Gont, F. and A. Yourtchenko, "On the Implementation of the
	TCP Urgent Mechanism", RFC 6093, January 2011.		TCP Urgent Mechanism", RFC 6093, January 2011.
	[RFC6298] Paxson, V., Allman, M., Chu, J., and M. Sargent,		[RFC6298] Paxson, V., Allman, M., Chu, J., and M. Sargent,
End of changes. 61 change blocks.
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