draft-ietf-tcpm-alternativebackoff-ecn-06.txt		draft-ietf-tcpm-alternativebackoff-ecn-07.txt
	Network Working Group N. Khademi		Network Working Group N. Khademi
	Internet-Draft M. Welzl		Internet-Draft M. Welzl
	Intended status: Experimental University of Oslo		Intended status: Experimental University of Oslo
	Expires: August 18, 2018 G. Armitage		Expires: September 21, 2018 G. Armitage
	Swinburne University of Technology		Swinburne University of Technology
	G. Fairhurst		G. Fairhurst
	University of Aberdeen		University of Aberdeen
	February 14, 2018		March 20, 2018
	TCP Alternative Backoff with ECN (ABE)		TCP Alternative Backoff with ECN (ABE)
	draft-ietf-tcpm-alternativebackoff-ecn-06		draft-ietf-tcpm-alternativebackoff-ecn-07
	Abstract		Abstract
	Active Queue Management (AQM) mechanisms allow for burst tolerance		Active Queue Management (AQM) mechanisms allow for burst tolerance
	while enforcing short queues to minimise the time that packets spend		while enforcing short queues to minimise the time that packets spend
	enqueued at a bottleneck. This can cause noticeable performance		enqueued at a bottleneck. This can cause noticeable performance
	degradation for TCP connections traversing such a bottleneck,		degradation for TCP connections traversing such a bottleneck,
	especially if there are only a few flows or their bandwidth-delay-		especially if there are only a few flows or their bandwidth-delay-
	product is large. An Explicit Congestion Notification (ECN) signal		product is large. An Explicit Congestion Notification (ECN) signal
	indicates that an AQM mechanism is used at the bottleneck, and		indicates that an AQM mechanism is used at the bottleneck, and
	skipping to change at page 1, line 45 ¶		skipping to change at page 1, line 45 ¶
	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 August 18, 2018.		This Internet-Draft will expire on September 21, 2018.
	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 3, line 11 ¶		skipping to change at page 3, line 11 ¶
	The rules for ECN were originally written to be very conservative,		The rules for ECN were originally written to be very conservative,
	and required the congestion control algorithms of ECN-Capable		and required the congestion control algorithms of ECN-Capable
	transport protocols to treat ECN congestion signals exactly the same		transport protocols to treat ECN congestion signals exactly the same
	as they would treat an inferred packet loss [RFC3168].		as they would treat an inferred packet loss [RFC3168].
	Research has demonstrated the benefits of reducing network delays		Research has demonstrated the benefits of reducing network delays
	that are caused by interaction of loss-based TCP congestion control		that are caused by interaction of loss-based TCP congestion control
	and excessive buffering [BUFFERBLOAT]. This has led to the creation		and excessive buffering [BUFFERBLOAT]. This has led to the creation
	of new AQM mechanisms like PIE [RFC8033] and CoDel		of new AQM mechanisms like PIE [RFC8033] and CoDel
	[CODEL2012][I-D.CoDel], which prevent bloated queues that are common		[CODEL2012][RFC8289], which prevent bloated queues that are common
	with unmanaged and excessively large buffers deployed across the		with unmanaged and excessively large buffers deployed across the
	Internet [BUFFERBLOAT].		Internet [BUFFERBLOAT].
	The AQM mechanisms mentioned above aim to keep a sustained queue		The AQM mechanisms mentioned above aim to keep a sustained queue
	short while tolerating transient (short-term) packet bursts.		short while tolerating transient (short-term) packet bursts.
	However, currently used loss-based congestion control mechanisms		However, currently used loss-based congestion control mechanisms
	cannot always utilise a bottleneck link well where there are short		cannot always utilise a bottleneck link well where there are short
	queues. For example, a TCP sender must be able to store at least an		queues. For example, a TCP sender must be able to store at least an
	end-to-end bandwidth-delay product (BDP) worth of data at the		end-to-end bandwidth-delay product (BDP) worth of data at the
	bottleneck buffer if it is to maintain full path utilisation in the		bottleneck buffer if it is to maintain full path utilisation in the
	skipping to change at page 3, line 35 ¶		skipping to change at page 3, line 35 ¶
	network path.		network path.
	Modern AQM mechanisms can use ECN to signal the early signs of		Modern AQM mechanisms can use ECN to signal the early signs of
	impending queue buildup long before a tail-drop queue would be forced		impending queue buildup long before a tail-drop queue would be forced
	to resort to dropping packets. It is therefore appropriate for the		to resort to dropping packets. It is therefore appropriate for the
	transport protocol congestion control algorithm to have a more		transport protocol congestion control algorithm to have a more
	measured response when an early-warning signal of congestion is		measured response when an early-warning signal of congestion is
	received in the form of an ECN CE-marked packet. Recognizing these		received in the form of an ECN CE-marked packet. Recognizing these
	changes in modern AQM practices, more recent rules have relaxed the		changes in modern AQM practices, more recent rules have relaxed the
	strict requirement that ECN signals be treated identically to		strict requirement that ECN signals be treated identically to
	inferred packet loss [I-D.ECN-exp]. Following these newer, more		inferred packet loss [RFC8311]. Following these newer, more flexible
	flexible rules, this document defines a new sender-side-only		rules, this document defines a new sender-side-only congestion
	congestion control response, called "ABE" (Alternative Backoff with		control response, called "ABE" (Alternative Backoff with ECN). ABE
	ECN). ABE improves TCP's average throughput when routers use AQM		improves TCP's average throughput when routers use AQM controlled
	controlled buffers that allow for short queues only.		buffers that allow for short queues only.
	2. Definitions		2. Definitions
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in RFC 2119 [RFC2119].		document are to be interpreted as described in RFC 2119 [RFC2119].
	3. Specification		3. Specification
	This specification updates the congestion control algorithm of an		This specification updates the congestion control algorithm of an
	skipping to change at page 4, line 21 ¶		skipping to change at page 4, line 21 ¶
	congestion loss in non-ECN-Capable TCP. That is, the TCP source		congestion loss in non-ECN-Capable TCP. That is, the TCP source
	halves the congestion window "cwnd" and reduces the slow start		halves the congestion window "cwnd" and reduces the slow start
	threshold "ssthresh".		threshold "ssthresh".
	Replacing this with:		Replacing this with:
	Receipt of a packet with the ECN-Echo flag SHOULD trigger the TCP		Receipt of a packet with the ECN-Echo flag SHOULD trigger the TCP
	source to set the slow start threshold (ssthresh) to 0.8 times the		source to set the slow start threshold (ssthresh) to 0.8 times the
	FlightSize, with a lower bound of 2 * SMSS applied to the result.		FlightSize, with a lower bound of 2 * SMSS applied to the result.
	As in [RFC5681], the TCP sender also reduces the cwnd value to no		As in [RFC5681], the TCP sender also reduces the cwnd value to no
	more than the new ssthresh value.		more than the new ssthresh value. RFC 3168 section 6.1.2 provides
			guidance on setting a cwnd less than 2 * SMSS.
	4. Discussion		4. Discussion
	Much of the technical background to ABE can be found in a research		Much of the technical background to ABE can be found in a research
	paper [ABE2017]. This paper used a mix of experiments, theory and		paper [ABE2017]. This paper used a mix of experiments, theory and
	simulations with NewReno [RFC5681] and CUBIC [I-D.CUBIC] to evaluate		simulations with NewReno [RFC5681] and CUBIC [RFC8312] to evaluate
	the technique. The technique was shown to present "...significant		the technique. The technique was shown to present "...significant
	performance gains in lightly-multiplexed [few concurrent flows]		performance gains in lightly-multiplexed [few concurrent flows]
	scenarios, without losing the delay-reduction benefits of deploying		scenarios, without losing the delay-reduction benefits of deploying
	CoDel or PIE". The performance improvement is achieved when reacting		CoDel or PIE". The performance improvement is achieved when reacting
	to ECN-Echo in congestion avoidance by multiplying cwnd and ssthresh		to ECN-Echo in congestion avoidance (when ssthresh > cwnd) by
	with a value in the range [0.7,0.85].		multiplying cwnd and ssthresh with a value in the range [0.7,0.85].
			Applying ABE when cwnd <= ssthresh is not currently recommended, but
			may benefit from additional attention, experimentation and
			specification.
	4.1. Why Use ECN to Vary the Degree of Backoff?		4.1. Why Use ECN to Vary the Degree of Backoff?
	The classic rule-of-thumb dictates that a network path needs to		AQM mechanisms such as CoDel [RFC8289] and PIE [RFC8033] set a delay
	provide a BDP of bottleneck buffering if a TCP connection wishes to		target in routers and use congestion notifications to constrain the
	optimise path utilisation. A single TCP bulk transfer running		queuing delays experienced by packets, rather than in response to
	through such a bottleneck will have increased its congestion window
	(cwnd) up to 2*BDP by the time that packet loss occurs. According to
	[RFC5681], when a TCP sender detects segment loss using the
	retransmission timer and the given segment has not yet been resent by
	way of the retransmission timer, the value of ssthresh must be set to
	no more of the maximum of half of the FlightSize and 2*SMSS. The
	same equation is also used during Fast Retransmit/Fast Recovery
	[RFC5681]. As a result, the TCP congestion control only allows one
	BDP of packets in flight. This is just sufficient to maintain 100%
	utilisation of the bottleneck on the network path.
	AQM mechanisms such as CoDel [I-D.CoDel] and PIE [RFC8033] set a
	delay target in routers and use congestion notifications to constrain
	the queuing delays experienced by packets, rather than in response to
	impending or actual bottleneck buffer exhaustion. With current		impending or actual bottleneck buffer exhaustion. With current
	default delay targets, CoDel and PIE both effectively emulate a		default delay targets, CoDel and PIE both effectively emulate a
	bottleneck with a short queue (section II, [ABE2017]) while also		bottleneck with a short queue (section II, [ABE2017]) while also
	allowing short traffic bursts into the queue. This provides		allowing short traffic bursts into the queue. This provides
	acceptable performance for TCP connections over a path with a low		acceptable performance for TCP connections over a path with a low
	BDP, or in highly multiplexed scenarios (many concurrent transport		BDP, or in highly multiplexed scenarios (many concurrent transport
	flows). However, in a lightly-multiplexed case over a path with a		flows). However, in a lightly-multiplexed case over a path with a
	large BDP, conventional TCP backoff leads to gaps in packet		large BDP, conventional TCP backoff leads to gaps in packet
	transmission and under-utilisation of the path.		transmission and under-utilisation of the path.
	skipping to change at page 5, line 43 ¶		skipping to change at page 5, line 32 ¶
	increase factor [ICC2002]. The goal of this former work was to		increase factor [ICC2002]. The goal of this former work was to
	operate across AQM bottlenecks using Random Early Detection (RED)		operate across AQM bottlenecks using Random Early Detection (RED)
	that were not necessarily configured to emulate a short queue (The		that were not necessarily configured to emulate a short queue (The
	current usage of RED as an Internet AQM method is limited [RFC7567]).		current usage of RED as an Internet AQM method is limited [RFC7567]).
	4.2. Focus on ECN as Defined in RFC3168		4.2. Focus on ECN as Defined in RFC3168
	Some transport protocol mechanisms rely on ECN semantics that differ		Some transport protocol mechanisms rely on ECN semantics that differ
	from the original ECN definition [RFC3168]. For instance, Accurate		from the original ECN definition [RFC3168]. For instance, Accurate
	ECN [I-D.ietf-tcpm-accurate-ecn] permits more frequent and detailed		ECN [I-D.ietf-tcpm-accurate-ecn] permits more frequent and detailed
	feedback. Use of mechanisms (such as Accurate ECN, Datacenter TCP		feedback. Use of such mechanisms (including Accurate ECN, Datacenter
	(DCTCP) [RFC8257], or Congestion Exposure (ConEx) [RFC7713]) is out		TCP (DCTCP) [RFC8257], or Congestion Exposure (ConEx) [RFC7713]) is
	of scope for this document. This specification focuses on ECN as		out of scope for this document. This specification focuses on ECN as
	defined in [RFC3168].		defined in [RFC3168].
	4.3. Choice of ABE Multiplier		4.3. Choice of ABE Multiplier
	ABE decouples the reaction of a TCP sender to inferred packet loss		ABE decouples the reaction of a TCP sender to inferred packet loss
	and ECN-signalled congestion in the congestion avoidance phase. To		and ECN-signalled congestion in the congestion avoidance phase. To
	achieve this, ABE uses different the scaling factor in Equation 4 in		achieve this, ABE uses a different scaling factor in Equation 4 in
	Section 3.1 of [RFC5681]. The description respectively uses		Section 3.1 of [RFC5681]. The description respectively uses
	beta_{loss} and beta_{ecn} to refer to the multiplicative decrease		beta_{loss} and beta_{ecn} to refer to the multiplicative decrease
	factors applied in response to inferred packet loss, and in response		factors applied in response to inferred packet loss, and in response
	to a receiver indicating ECN-signalled congestion. For non-ECN-		to a receiver indicating ECN-signalled congestion. For non-ECN-
	enabled TCP connections, only beta_{loss} applies.		enabled TCP connections, only beta_{loss} applies.
	In other words, in response to inferred packet loss:		In other words, in response to inferred packet loss:
	ssthresh = max (FlightSize * beta_{loss}, 2 * SMSS)		ssthresh = max (FlightSize * beta_{loss}, 2 * SMSS)
	and in response to an indication of an ECN-signalled congestion:		and in response to an indication of an ECN-signalled congestion:
	ssthresh = max (FlightSize * beta_{ecn}, 2 * SMSS)		ssthresh = max (FlightSize * beta_{ecn}, 2 * SMSS)
	and		and
	cwnd = ssthresh		cwnd = ssthresh
			(If ssthresh == 2 * SMSS, RFC 3168 section 6.1.2 provides guidance
			on setting a cwnd lower than 2 * SMSS.)
	where FlightSize is the amount of outstanding data in the network,		where FlightSize is the amount of outstanding data in the network,
	upper-bounded by the smaller of the sender's cwnd and the receiver's		upper-bounded by the smaller of the sender's cwnd and the receiver's
	advertised window (rwnd) [RFC5681]. The higher the values of		advertised window (rwnd) [RFC5681]. The higher the values of
	beta_{loss} and beta_{ecn}, the less aggressive the response of any		beta_{loss} and beta_{ecn}, the less aggressive the response of any
	individual backoff event.		individual backoff event.
	The appropriate choice for beta_{loss} and beta_{ecn} values is a		The appropriate choice for beta_{loss} and beta_{ecn} values is a
	balancing act between path utilisation and draining the bottleneck		balancing act between path utilisation and draining the bottleneck
	queue. More aggressive backoff (smaller beta_*) risks underutilising		queue. More aggressive backoff (smaller beta_*) risks underutilising
	the path, while less aggressive backoff (larger beta_*) can result in		the path, while less aggressive backoff (larger beta_*) can result in
	slower draining of the bottleneck queue.		slower draining of the bottleneck queue.
	The Internet has already been running with at least two different		The Internet has already been running with at least two different
	beta_{loss} values for several years: the standard value is 0.5		beta_{loss} values for several years: the standard value is 0.5
	[RFC5681], and the Linux implementation of CUBIC [I-D.CUBIC] has used		[RFC5681], and the Linux implementation of CUBIC [RFC8312] has used a
	a multiplier of 0.7 since kernel version 2.6.25 released in 2008.		multiplier of 0.7 since kernel version 2.6.25 released in 2008. ABE
	ABE proposes no change to beta_{loss} used by current TCP		proposes no change to beta_{loss} used by current TCP
	implementations.		implementations.
	The recommendation in Section 3 in this document corresponds to a		The recommendation in Section 3 in this document corresponds to a
	value of beta_{ecn}=0.8. This recommended beta_{ecn} value is only		value of beta_{ecn}=0.8. This recommended beta_{ecn} value is only
	applicable for the standard TCP congestion control [RFC5681]. The		applicable for the standard TCP congestion control [RFC5681]. The
	selection of beta_{ecn} enables tuning the response of a TCP		selection of beta_{ecn} enables tuning the response of a TCP
	connection to shallow AQM marking thresholds. beta_{loss}		connection to shallow AQM marking thresholds. beta_{loss}
	characterizes the response of a congestion control algorithm to		characterizes the response of a congestion control algorithm to
	packet loss, i.e., exhaustion of buffers (of unknown depth).		packet loss, i.e., exhaustion of buffers (of unknown depth).
	Different values for beta_{loss} have been suggested for TCP		Different values for beta_{loss} have been suggested for TCP
	congestion control algorithms. Consequently, beta_{ecn} is likely to		congestion control algorithms. Consequently, beta_{ecn} is likely to
	be an algorithm-specific parameter rather than a constant multiple of		be an algorithm-specific parameter rather than a constant multiple of
	the algorithm's existing beta_{loss}.		the algorithm's existing beta_{loss}.
	A range of tests (section IV, [ABE2017]) with NewReno and CUBIC over		A range of tests (section IV, [ABE2017]) with NewReno and CUBIC over
	CoDel and PIE in lightly-multiplexed scenarios have explored this		CoDel and PIE in lightly-multiplexed scenarios have explored this
	choice of parameter. The results of these tests indicate that CUBIC		choice of parameter. The results of these tests indicate that CUBIC
	skipping to change at page 7, line 22 ¶		skipping to change at page 7, line 17 ¶
	5. ABE Deployment Requirements		5. ABE Deployment Requirements
	This update is a sender-side only change. Like other changes to		This update is a sender-side only change. Like other changes to
	congestion control algorithms, it does not require any change to the		congestion control algorithms, it does not require any change to the
	TCP receiver or to network devices. It does not require any ABE-		TCP receiver or to network devices. It does not require any ABE-
	specific changes in routers or the use of Accurate ECN feedback		specific changes in routers or the use of Accurate ECN feedback
	[I-D.ietf-tcpm-accurate-ecn] by a receiver.		[I-D.ietf-tcpm-accurate-ecn] by a receiver.
	RFC3168 states that the congestion control response to an ECN-		RFC3168 states that the congestion control response to an ECN-
	signalled congestion is the same as the response to a dropped packet		signalled congestion is the same as the response to a dropped packet
	[RFC3168]. [I-D.ECN-exp] updates this specification to allow systems		[RFC3168]. [RFC8311] updates this specification to allow systems to
	to provide a different behaviour when they experience ECN-signalled		provide a different behaviour when they experience ECN-signalled
	congestion rather than packet loss. The present specification		congestion rather than packet loss. The present specification
	defines such an experiment and has thus been assigned an Experimental		defines such an experiment and has thus been assigned an Experimental
	status before being proposed as a Standards-Track update.		status before being proposed as a Standards-Track update.
	The purpose of the Internet experiment is to collect experience with		The purpose of the Internet experiment is to collect experience with
	deployment of ABE, and confirm the safety in deployed networks using		deployment of ABE, and confirm the safety in deployed networks using
	this update to TCP congestion control.		this update to TCP congestion control.
	When used with bottlenecks that do not support ECN-marking the		When used with bottlenecks that do not support ECN-marking the
	specification does not modify the transport protocol.		specification does not modify the transport protocol.
	skipping to change at page 8, line 51 ¶		skipping to change at page 8, line 46 ¶
	XX RFC ED - PLEASE REMOVE THIS SECTION XXX		XX RFC ED - PLEASE REMOVE THIS SECTION XXX
	This document includes no request to IANA.		This document includes no request to IANA.
	8. Implementation Status		8. Implementation Status
	ABE is implemented as a patch for Linux and FreeBSD. It is meant for		ABE is implemented as a patch for Linux and FreeBSD. It is meant for
	research and available for download from		research and available for download from
	http://heim.ifi.uio.no/naeemk/research/ABE/. This code was used to		http://heim.ifi.uio.no/naeemk/research/ABE/. This code was used to
	produce the test results that are reported in [ABE2017]. An evolved		produce the test results that are reported in [ABE2017]. The FreeBSD
	version of the patch for FreeBSD is currently under review for		code has been committed to the mainline kernel on March 19, 2018
	potential inclusion in the mainline kernel [ABE-FreeBSD].		[ABE-FreeBSD].
	9. Security Considerations		9. Security Considerations
	The described method is a sender-side only transport change, and does		The described method is a sender-side only transport change, and does
	not change the protocol messages exchanged. The security		not change the protocol messages exchanged. The security
	considerations for ECN [RFC3168] therefore still apply.		considerations for ECN [RFC3168] therefore still apply.
	This is a change to TCP congestion control with ECN that will		This is a change to TCP congestion control with ECN that will
	typically lead to a change in the capacity achieved when flows share		typically lead to a change in the capacity achieved when flows share
	a network bottleneck. This could result in some flows receiving more		a network bottleneck. This could result in some flows receiving more
	than their fair share of capacity. Similar unfairness in the way		than their fair share of capacity. Similar unfairness in the way
	that capacity is shared is also exhibited by other congestion control		that capacity is shared is also exhibited by other congestion control
	mechanisms that have been in use in the Internet for many years		mechanisms that have been in use in the Internet for many years
	(e.g., CUBIC [I-D.CUBIC]). Unfairness may also be a result of other		(e.g., CUBIC [RFC8312]). Unfairness may also be a result of other
	factors, including the round trip time experienced by a flow. ABE		factors, including the round trip time experienced by a flow. ABE
	applies only when ECN-marked packets are received, not when packets		applies only when ECN-marked packets are received, not when packets
	are lost, hence use of ABE cannot lead to congestion collapse.		are lost, hence use of ABE cannot lead to congestion collapse.
	10. Revision Information		10. Revision Information
	XX RFC ED - PLEASE REMOVE THIS SECTION XXX		XX RFC ED - PLEASE REMOVE THIS SECTION XXX
			-07. Addressed comments following WGLC.
			o Updated Reference citations
			o Removed paragraph containing a wrong statement related to timeout
			in section 4.1.
			o Discuss what happens when cwnd <= ssthresh
			o Added text on Concern about lower bound of 2*SMSS
	-06. Addressed Michael Scharf's comments.		-06. Addressed Michael Scharf's comments.
	-05. Refined the description of the experiment based on feedback at		-05. Refined the description of the experiment based on feedback at
	IETF-100. Incorporated comments from David Black.		IETF-100. Incorporated comments from David Black.
	-04. Incorporates review comments from Lawrence Stewart and the		-04. Incorporates review comments from Lawrence Stewart and the
	remaining comments from Roland Bless. References are updated.		remaining comments from Roland Bless. References are updated.
	-03. Several review comments from Roland Bless are addressed.		-03. Several review comments from Roland Bless are addressed.
	Consistent terminology and equations. Clarification on the scope of		Consistent terminology and equations. Clarification on the scope of
	skipping to change at page 10, line 29 ¶		skipping to change at page 10, line 37 ¶
	Individual draft -00. draft-khademi-tsvwg-ecn-response-00 and draft-		Individual draft -00. draft-khademi-tsvwg-ecn-response-00 and draft-
	khademi-tcpm-alternativebackoff-ecn-00 replace draft-khademi-		khademi-tcpm-alternativebackoff-ecn-00 replace draft-khademi-
	alternativebackoff-ecn-03, following discussion in the TSVWG and TCPM		alternativebackoff-ecn-03, following discussion in the TSVWG and TCPM
	working groups.		working groups.
	11. References		11. References
	11.1. Normative References		11.1. Normative References
	[I-D.ECN-exp]
	Black, D., "Explicit Congestion Notification (ECN)
	Experimentation", Internet-draft, IETF work-in-progress
	draft-ietf-tsvwg-ecn-experimentation-08, November 2017.
	[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,
	DOI 10.17487/RFC2119, March 1997,		DOI 10.17487/RFC2119, March 1997,
	<https://www.rfc-editor.org/info/rfc2119>.		<https://www.rfc-editor.org/info/rfc2119>.
	[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",		of Explicit Congestion Notification (ECN) to IP",
	RFC 3168, DOI 10.17487/RFC3168, September 2001,		RFC 3168, DOI 10.17487/RFC3168, September 2001,
	<https://www.rfc-editor.org/info/rfc3168>.		<https://www.rfc-editor.org/info/rfc3168>.
	skipping to change at page 11, line 10 ¶		skipping to change at page 11, line 15 ¶
	[RFC7567] Baker, F., Ed. and G. Fairhurst, Ed., "IETF		[RFC7567] Baker, F., Ed. and G. Fairhurst, Ed., "IETF
	Recommendations Regarding Active Queue Management",		Recommendations Regarding Active Queue Management",
	BCP 197, RFC 7567, DOI 10.17487/RFC7567, July 2015,		BCP 197, RFC 7567, DOI 10.17487/RFC7567, July 2015,
	<https://www.rfc-editor.org/info/rfc7567>.		<https://www.rfc-editor.org/info/rfc7567>.
	[RFC8257] Bensley, S., Thaler, D., Balasubramanian, P., Eggert, L.,		[RFC8257] Bensley, S., Thaler, D., Balasubramanian, P., Eggert, L.,
	and G. Judd, "Data Center TCP (DCTCP): TCP Congestion		and G. Judd, "Data Center TCP (DCTCP): TCP Congestion
	Control for Data Centers", RFC 8257, DOI 10.17487/RFC8257,		Control for Data Centers", RFC 8257, DOI 10.17487/RFC8257,
	October 2017, <https://www.rfc-editor.org/info/rfc8257>.		October 2017, <https://www.rfc-editor.org/info/rfc8257>.
			[RFC8311] Black, D., "Relaxing Restrictions on Explicit Congestion
			Notification (ECN) Experimentation", RFC 8311,
			DOI 10.17487/RFC8311, January 2018,
			<https://www.rfc-editor.org/info/rfc8311>.
	11.2. Informative References		11.2. Informative References
	[ABE-FreeBSD]		[ABE-FreeBSD]
	"ABE patch review in FreeBSD",		"ABE patch review in FreeBSD",
	<https://reviews.freebsd.org/D11616>.		<https://svnweb.freebsd.org/
			base?view=revision&revision=331214>.
	[ABE2017] Khademi, N., Armitage, G., Welzl, M., Fairhurst, G.,		[ABE2017] Khademi, N., Armitage, G., Welzl, M., Fairhurst, G.,
	Zander, S., and D. Ros, "Alternative Backoff: Achieving		Zander, S., and D. Ros, "Alternative Backoff: Achieving
	Low Latency and High Throughput with ECN and AQM", IFIP		Low Latency and High Throughput with ECN and AQM", IFIP
	NETWORKING 2017, Stockholm, Sweden, June 2017.		NETWORKING 2017, Stockholm, Sweden, June 2017.
	[BUFFERBLOAT]		[BUFFERBLOAT]
	Gettys, J. and K. Nichols, "Bufferbloat: Dark Buffers in		Gettys, J. and K. Nichols, "Bufferbloat: Dark Buffers in
	the Internet", November 2011.		the Internet", November 2011.
	[CODEL2012]		[CODEL2012]
	Nichols, K. and V. Jacobson, "Controlling Queue Delay",		Nichols, K. and V. Jacobson, "Controlling Queue Delay",
	July 2012, <http://queue.acm.org/detail.cfm?id=2209336>.		July 2012, <http://queue.acm.org/detail.cfm?id=2209336>.
	[I-D.CoDel]
	Nichols, K., Jacobson, V., McGregor, V., and J. Iyengar,
	"Controlled Delay Active Queue Management", Internet-
	draft, IETF work-in-progress draft-ietf-aqm-codel-10,
	October 2017.
	[I-D.CUBIC]
	Rhee, I., Xu, L., Ha, S., Zimmermann, A., Eggert, L., and
	R. Scheffenegger, "CUBIC for Fast Long-Distance Networks",
	Internet-draft, IETF work-in-progress draft-ietf-tcpm-
	cubic-07, November 2017.
	[I-D.ietf-tcpm-accurate-ecn]		[I-D.ietf-tcpm-accurate-ecn]
	Briscoe, B., Kuehlewind, M., and R. Scheffenegger, "More		Briscoe, B., Kuehlewind, M., and R. Scheffenegger, "More
	Accurate ECN Feedback in TCP", draft-ietf-tcpm-accurate-		Accurate ECN Feedback in TCP", draft-ietf-tcpm-accurate-
	ecn-03 (work in progress), May 2017.		ecn-06 (work in progress), March 2018.
	[ICC2002] Kwon, M. and S. Fahmy, "TCP Increase/Decrease Behavior		[ICC2002] Kwon, M. and S. Fahmy, "TCP Increase/Decrease Behavior
	with Explicit Congestion Notification (ECN)", IEEE		with Explicit Congestion Notification (ECN)", IEEE
	ICC 2002, New York, New York, USA, May 2002,		ICC 2002, New York, New York, USA, May 2002,
	<http://dx.doi.org/10.1109/ICC.2002.997262>.		<http://dx.doi.org/10.1109/ICC.2002.997262>.
	[RFC7713] Mathis, M. and B. Briscoe, "Congestion Exposure (ConEx)		[RFC7713] Mathis, M. and B. Briscoe, "Congestion Exposure (ConEx)
	Concepts, Abstract Mechanism, and Requirements", RFC 7713,		Concepts, Abstract Mechanism, and Requirements", RFC 7713,
	DOI 10.17487/RFC7713, December 2015,		DOI 10.17487/RFC7713, December 2015,
	<https://www.rfc-editor.org/info/rfc7713>.		<https://www.rfc-editor.org/info/rfc7713>.
	skipping to change at page 12, line 21 ¶		skipping to change at page 12, line 21 ¶
	"Proportional Integral Controller Enhanced (PIE): A		"Proportional Integral Controller Enhanced (PIE): A
	Lightweight Control Scheme to Address the Bufferbloat		Lightweight Control Scheme to Address the Bufferbloat
	Problem", RFC 8033, DOI 10.17487/RFC8033, February 2017,		Problem", RFC 8033, DOI 10.17487/RFC8033, February 2017,
	<https://www.rfc-editor.org/info/rfc8033>.		<https://www.rfc-editor.org/info/rfc8033>.
	[RFC8087] Fairhurst, G. and M. Welzl, "The Benefits of Using		[RFC8087] Fairhurst, G. and M. Welzl, "The Benefits of Using
	Explicit Congestion Notification (ECN)", RFC 8087,		Explicit Congestion Notification (ECN)", RFC 8087,
	DOI 10.17487/RFC8087, March 2017,		DOI 10.17487/RFC8087, March 2017,
	<https://www.rfc-editor.org/info/rfc8087>.		<https://www.rfc-editor.org/info/rfc8087>.
			[RFC8289] Nichols, K., Jacobson, V., McGregor, A., Ed., and J.
			Iyengar, Ed., "Controlled Delay Active Queue Management",
			RFC 8289, DOI 10.17487/RFC8289, January 2018,
			<https://www.rfc-editor.org/info/rfc8289>.
			[RFC8312] Rhee, I., Xu, L., Ha, S., Zimmermann, A., Eggert, L., and
			R. Scheffenegger, "CUBIC for Fast Long-Distance Networks",
			RFC 8312, DOI 10.17487/RFC8312, February 2018,
			<https://www.rfc-editor.org/info/rfc8312>.
	Authors' Addresses		Authors' Addresses
	Naeem Khademi		Naeem Khademi
	University of Oslo		University of Oslo
	PO Box 1080 Blindern		PO Box 1080 Blindern
	Oslo N-0316		Oslo N-0316
	Norway		Norway
	Email: naeemk@ifi.uio.no		Email: naeemk@ifi.uio.no
End of changes. 25 change blocks.
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