wdiff rfc8511.original rfc8511.txt

Network Working Group
Internet Engineering Task Force (IETF) N. Khademi
Internet-Draft
Request for Comments: 8511 M. Welzl
Intended status:
Category: Experimental University of Oslo
Expires: March 18, 2019
ISSN: 2070-1721 G. Armitage
Netflix
G. Fairhurst
University of Aberdeen
September 14,
December 2018

TCP Alternative Backoff with ECN (ABE)
draft-ietf-tcpm-alternativebackoff-ecn-12

Abstract

Active Queue Management (AQM) mechanisms allow for burst tolerance
while enforcing short queues to minimise the time that packets spend
enqueued at a bottleneck. This can cause noticeable performance
degradation for TCP connections traversing such a bottleneck,
especially if there are only a few flows or their bandwidth-delay- bandwidth-delay
product (BDP) is large. The reception of a Congestion Experienced
(CE) ECN Explicit Congestion Notification (ECN) mark indicates that an
AQM mechanism is used at the bottleneck, and
therefore the bottleneck network
queue is therefore likely to be short. Feedback of this signal
allows the TCP sender-side ECN reaction in congestion avoidance to
reduce the Congestion Window (cwnd) by a smaller amount than the
congestion control algorithm's reaction to inferred packet loss. This
Therefore, this specification therefore defines an experimental change to the
TCP reaction specified in RFC3168, RFC 3168, as permitted by RFC 8311.

Status of This Memo

This Internet-Draft document is submitted in full conformance with the
provisions of BCP 78 not an Internet Standards Track specification; it is
published for examination, experimental implementation, and BCP 79.

Internet-Drafts are working documents
evaluation.

This document defines an Experimental Protocol for the Internet
community. This document is a product of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list It represents the consensus of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.

Internet-Drafts are draft the IETF
community. It has received public review and has been approved for
publication by the Internet Engineering Steering Group (IESG). Not
all documents valid approved by the IESG are candidates for a maximum any level of
Internet Standard; see Section 2 of RFC 7841.

Information about the current status of six months this document, any errata,
and how to provide feedback on it may be updated, replaced, or obsoleted by other documents obtained at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."

This Internet-Draft will expire on March 18, 2019.
https://www.rfc-editor.org/info/rfc8511.

This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
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described in the Simplified BSD License.

Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 3
2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 3 4
3. Specification . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Choice of ABE Multiplier . . . . . . . . . . . . . . . . 4
4. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.1. Why Use Rationale for Using ECN to Vary the Degree of Backoff? . . . . . Backoff . . 6
4.2. An RTT-based response RTT-Based Response to indicated congestion Indicated Congestion . . . . . . 7
5. ABE Deployment Requirements . . . . . . . . . . . . . . . . . 7
6. ABE Experiment Goals . . . . . . . . . . . . . . . . . . . . 8
7. Acknowledgements . IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
8. IANA Security Considerations . . . . . . . . . . . . . . . . . . . . . 9 8
9. Implementation Status . . . . . . . . . . . . . . References . . . . . . 9
10. Security Considerations . . . . . . . . . . . . . . . . . . . 9
11. Revision Information . .
9.1. Normative References . . . . . . . . . . . . . . . . . . 9
12.
9.2. Informative References . . . . . . . . . . . . . . . . . 9
Acknowledgements . . . . . . . . 11
12.1. Normative References . . . . . . . . . . . . . . . . . . 11
12.2. Informative References . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13 12

1. Introduction

Explicit Congestion Notification (ECN) [RFC3168] makes it possible
for an Active Queue Management (AQM) mechanism to signal the presence
of incipient congestion without necessarily incurring packet loss.
This lets the network deliver some packets to an application that
would have been dropped if the application or transport did not
support ECN. This packet loss reduction is the most obvious benefit
of ECN, but it is often relatively modest. Other benefits of
deploying ECN have been documented in RFC8087 [RFC8087].

The rules for ECN were originally written to be very conservative,
and they required the congestion control algorithms of ECN-Capable
transport
Transport (ECT) protocols to treat indications of congestion
signalled by ECN exactly the same as they would treat an inferred
packet loss [RFC3168]. Research has demonstrated the benefits of
reducing network delays that are caused by interaction of loss-based
TCP congestion control and excessive buffering [BUFFERBLOAT]. This
has led to the creation of AQM mechanisms like Proportional Integral
Controller Enhanced (PIE) [RFC8033] and Controlling Queue Delay
(CoDel) [CODEL2012][RFC8289], [RFC8289], which prevent bloated queues that are common with
unmanaged and excessively large buffers deployed across the Internet
[BUFFERBLOAT].

The AQM mechanisms mentioned above aim to keep a sustained queue
short while tolerating transient (short-term) packet bursts.
However, currently used loss-based congestion control mechanisms are
not always able to effectively utilise a bottleneck link where there
are short queues. For example, a TCP sender using the Reno
congestion control needs to be able to store at least an end-to-end
bandwidth-delay product (BDP) worth of data at the bottleneck buffer
if it is to maintain full path utilisation in the face of loss-
induced reduction of the congestion window (cwnd) [RFC5681]. This
amount of buffering effectively doubles the amount of data that can
be in flight and the maximum round-trip time (RTT) experienced by the
TCP sender.

Modern AQM mechanisms can use ECN to signal the early signs of
impending queue buildup long before a tail-drop queue would be forced
to resort to dropping packets. It is therefore appropriate for the
transport protocol congestion control algorithm to have a more
measured response when it receives an indication with an early- early
warning of congestion after the remote endpoint receives an ECN CE-
marked packet. Recognizing these changes in modern AQM practices,
the strict requirement that ECN CE signals be treated identically to
inferred packet loss has been relaxed [RFC8311]. This document
therefore defines a new sender-side-only congestion control response, response
called "ABE" (Alternative Backoff with ECN). ABE improves TCP's
average throughput when routers use AQM controlled AQM-controlled buffers that allow
only for short queues.

2. Definitions

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 RFC 2119 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.

3. Specification

This specification changes the congestion control algorithm of an
ECN-Capable TCP transport protocol by changing the TCP sender TCP-sender
response to feedback from the TCP receiver that indicates the
reception of a CE-marked packet, i.e., receipt of a packet with the
ECN-Echo flag (defined in [RFC3168]) set, following the process
defined in [RFC8311].

The TCP sender TCP-sender response is currently specified in section Section 6.1.2 of
the ECN specification [RFC3168], [RFC3168] and has been slightly updated by [RFC8311]:
Section 4.1 of [RFC8311] to read as:

The indication of congestion should be treated just as a
congestion loss in non-ECN-Capable TCP. That is, the TCP source
halves the congestion window "cwnd" and reduces the slow start
threshold "ssthresh", unless otherwise specified by an
Experimental RFC in the IETF document stream.

Following publication of

As permitted by RFC 8311, this document specifies a sender-
side sender-side
change to TCP:

Receipt TCP where 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 FlightSize, with a lower bound of 2 * SMSS applied to
the result. result (where SMSS stands for Sender Maximum Segment Size)). As
in [RFC5681], the TCP sender also reduces the cwnd value to no more
than the new ssthresh value. Section 6.1.2 of RFC 3168 section 6.1.2 provides
guidance on setting a cwnd less than 2 * SMSS.

3.1. Choice of ABE Multiplier

ABE decouples the reaction of a TCP sender to inferred packet loss
and
from the indication of ECN-signalled congestion in the congestion
avoidance phase. To achieve this, ABE uses a different scaling
factor in for Equation 4 in Section 3.1 of [RFC5681]. The description
respectively uses beta_{loss} and beta_{ecn} to refer to the
multiplicative decrease factors applied in response to inferred
packet loss, and in response to a receiver indicating ECN-signalled
congestion. For non-ECN-enabled TCP connections, only beta_{loss}
applies.

In other words, in response to inferred packet loss:

ssthresh = max (FlightSize * beta_{loss}, 2 * SMSS)

and in response to an indication of an ECN-signalled congestion:

ssthresh = max (FlightSize * beta_{ecn}, 2 * SMSS)

and

cwnd = ssthresh

(If ssthresh == 2 * SMSS, Section 6.1.2 of 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,
upper-bounded by the smaller of the sender's cwnd and the receiver's
advertised window (rwnd) [RFC5681]. The higher the values of
beta_{loss} and beta_{ecn}, the less aggressive the response of any
individual backoff event.

The appropriate choice for beta_{loss} and beta_{ecn} values is a
balancing act between path utilisation and draining the bottleneck
queue. More aggressive backoff (smaller beta_*) risks underutilising the
underutilisation of the path, while less aggressive less-aggressive backoff (larger
beta_*) can result in slower draining of the bottleneck queue.

The Internet has already been running with at least two different
beta_{loss} values for several years: the standard value is 0.5
[RFC5681], and the Linux implementation of CUBIC [RFC8312] has used a
multiplier of 0.7 since kernel version 2.6.25 released in 2008. ABE
does not change the value of beta_{loss} used by current TCP
implementations.

The recommendation in this document specifies a value of
beta_{ecn}=0.8. This recommended beta_{ecn} value is only applicable
for the standard TCP congestion control [RFC5681]. The selection of
beta_{ecn} enables tuning the response of a TCP connection to shallow
AQM marking
AQM-marking thresholds. beta_{loss} characterizes the response of a
congestion control algorithm to packet loss, i.e., exhaustion of
buffers (of unknown depth). Different values for beta_{loss} have
been suggested for TCP congestion control algorithms. Consequently,
beta_{ecn} is likely to be an algorithm-specific parameter rather
than a constant multiple of the algorithm's existing beta_{loss}.

A range of tests (section IV, (Section IV of [ABE2017]) with NewReno and CUBIC
over CoDel and PIE in lightly-multiplexed lightly multiplexed scenarios have explored
this choice of parameter. The results of these tests indicate that
CUBIC connections benefit from beta_{ecn} of 0.85 (cf. beta_{loss} =
0.7), and NewReno connections see improvements with beta_{ecn} in the
range 0.7 to 0.85 (cf. beta_{loss} = 0.5).

4. Discussion

Much of the technical background to for ABE can be found in a research
paper [ABE2017]. This paper used [ABE2017],
which uses a mix of experiments, theory theory, and simulations with NewReno
[RFC5681] and CUBIC [RFC8312] to evaluate
the technique. The technique its performance. ABE was
shown to present "...significant significant performance gains in lightly-multiplexed [few
(few concurrent flows] flows) scenarios, without losing the delay-reduction
benefits of deploying CoDel or PIE". PIE. The performance improvement is
achieved when reacting to ECN-Echo in congestion avoidance (when
ssthresh > cwnd) by multiplying cwnd and ssthresh with a value in the
range [0.7,0.85]. Applying ABE when cwnd <= is smaller than or equal to
ssthresh is not currently recommended, but its use in that scenario
may benefit from additional attention, experimentation experimentation, and
specification.

4.1. Why Use Rationale for Using ECN to Vary the Degree of Backoff? Backoff

AQM mechanisms such as CoDel [RFC8289] and PIE [RFC8033] set a delay
target in routers and use congestion notifications to constrain the
queuing delays experienced by packets, packets rather than in response to
impending or actual bottleneck buffer exhaustion. With current
default delay targets, CoDel and PIE both effectively emulate a
bottleneck with a short queue (section II, (Section II of [ABE2017]) while also
allowing short traffic bursts into the queue. This provides
acceptable performance for TCP connections over a path with a low
BDP, or in highly multiplexed scenarios (many concurrent transport
flows). However, in a lightly-multiplexed lightly multiplexed case over a path with a
large BDP, conventional TCP backoff leads to gaps in packet
transmission and under-utilisation underutilisation of the path.

Instead of discarding packets, an AQM mechanism is allowed to mark
ECN-Capable packets with an ECN CE-mark. CE mark. The reception of a CE-mark
feedback not only indicates congestion on the network path, it also
indicates that an AQM mechanism exists at the bottleneck along the
path, and hence
path. Therefore, the CE-mark CE mark likely came from a bottleneck with a
controlled short queue. Reacting differently to an ECN-signalled
congestion than to an inferred packet loss can then yield the benefit
of a reduced back-off backoff when queues are short. Using ECN can also be
advantageous for several other reasons [RFC8087].

The idea of reacting differently to inferred packet loss and
detection of an ECN-signalled congestion pre-dates predates this
specification. For example, specification,
e.g., previous research proposed using ECN CE-
marked CE-marked feedback to
modify TCP congestion control behaviour via a larger multiplicative
decrease factor in conjunction with a smaller additive increase
factor [ICC2002]. The goal of this former work was to operate across
AQM bottlenecks using (using Random Early Detection (RED) (RED)) that were not
necessarily configured to emulate a short queue queue. (The current usage
of RED as an Internet AQM method is limited [RFC7567]). [RFC7567].)

4.2. An RTT-based response RTT-Based Response to indicated congestion Indicated Congestion

This specification applies to the use of ECN feedback as defined in
[RFC3168], which specifies a response to indicated congestion that is
no more frequent that than once per path round trip round-trip time. Since ABE
responds to indicated congestion once per RTT, it therefore does not respond to
any further loss within the same RTT, RTT because an ABE sender has
already reduced the congestion window. If congestion persists after
such reduction, ABE continues to reduce the congestion window in each
consecutive RTT. This consecutive reduction can protect the network
against long-standing unfairness in the case of AQM algorithms that
do not keep a small average queue length. The mechanism does not
rely on Accurate ECN
([I-D.ietf-tcpm-accurate-ecn]). [ACC-ECN-FEEDBACK].

In contrast, transport protocol mechanisms can also be designed to
utilise more frequent and detailed ECN feedback (e.g., Accurate ECN
[I-D.ietf-tcpm-accurate-ecn]),
[ACC-ECN-FEEDBACK]), which then permit a congestion control response
that adjusts the sending rate more frequently. Datacenter Data Center TCP
(DCTCP) [RFC8257] is an example of this approach.

5. ABE Deployment Requirements

This update is a sender-side only sender-side-only change. Like other changes to
congestion control algorithms, it does not require any change to the
TCP receiver or to network devices. It does not require any ABE-
specific changes in routers or the use of Accurate ECN feedback
[I-D.ietf-tcpm-accurate-ecn]
[ACC-ECN-FEEDBACK] by a receiver.

If the method is only deployed by some senders, and not by others,
the senders that use this method using it can gain some advantage, possibly at the expense
of other flows that do not use this updated method. Because this
advantage applies only to ECN-marked packets and not to
packet loss packet-loss
indications, an ECN-Capable bottleneck will still fall back to
dropping packets if an a TCP sender using ABE is too
aggressive, and the aggressive. The
result is no different than if the TCP sender was were using traditional
loss-based congestion control.

When used with bottlenecks that do not support ECN-marking ECN marking, the
specification does not modify the transport protocol.

6. ABE Experiment Goals

[RFC3168] states that the congestion control response following an
indication of ECN-signalled congestion is the same as the response to
a dropped packet. [RFC8311] updates this specification to allow
systems to provide a different behaviour when they experience ECN-
signalled congestion rather than packet loss. The present
specification defines such an experiment and has thus been assigned is an Experimental status before being proposed RFC.
We expect to propose it as a Standards-Track
update. document in the future.

The purpose of the Internet experiment is to collect experience with
the deployment of ABE, ABE and confirm acceptable safety in deployed
networks that use this update to TCP congestion control. To evaluate
ABE, this experiment therefore requires support in AQM routers for the ECN-
marking of packets carrying the ECN-Capable Transport, ECT(0), Transport codepoint
ECT(0) [RFC3168].

The result of this Internet experiment ought to include an
investigation of the implications of experiencing an ECN-CE mark
followed by loss within the same RTT. At the end of the experiment,
this will be reported to the TCPM WG Working Group or the IESG.

7. Acknowledgements

Authors N. Khademi, M. Welzl

ABE is implemented as a patch for Linux and G. Fairhurst were part-funded by
the European Community under its Seventh Framework Programme through FreeBSD. This is meant
for research and experimentation and is available for download at
<https://heim.ifi.uio.no/michawe/research/abe/>. This code was used
to produce the Reducing Internet Transport Latency (RITE) project (ICT-317700).
The views expressed test results that are solely those of reported in [ABE2017]. The
FreeBSD code was committed to the authors.

Author G. Armitage performed most of his work mainline kernel on this March 19, 2018
[ABE-REVISION].

7. IANA Considerations

This document while
employed by Swinburne University of Technology, Melbourne, Australia. has no IANA actions.

8. Security Considerations

The authors would like to thank Stuart Cheshire for many suggestions
when revising the draft, described method is a sender-side-only transport change, and it
does not change the following people for their
contributions to [ABE2017]: Chamil Kulatunga, David Ros, Stein
Gjessing, Sebastian Zander. Thanks also to (in alphabetical order)
Roland Bless, Bob Briscoe, David Black, Markku Kojo, John Leslie,
Lawrence Stewart, Dave Taht and the TCPM Working Group for providing
valuable feedback on this document.

The authors would finally like to thank everyone who provided
feedback on the congestion control behaviour specified in this update
received from the IRTF Internet Congestion Control Research Group
(ICCRG).

8. IANA Considerations

XX RFC ED - PLEASE REMOVE THIS SECTION XXX

This document includes no request to IANA.

9. Implementation Status

ABE is implemented as a patch for Linux and FreeBSD. This is meant
for research and available for download from
http://heim.ifi.uio.no/michawe/research/abe/. This code was used to
produce the test results that are reported in [ABE2017]. The FreeBSD
code has been committed to the mainline kernel on March 19, 2018
[ABE-FreeBSD].

10. Security Considerations

The described method is a sender-side only transport change, and does
not change the protocol messages exchanged. The security
considerations protocol messages exchanged. Therefore, the
security considerations for ECN [RFC3168] therefore still apply.

This is a change to TCP congestion control with ECN that will
typically lead to a change in the capacity achieved when flows share
a network bottleneck. This could result in some flows receiving more
than their fair share of capacity. Similar unfairness in the way
that capacity is shared is also exhibited by other congestion control
mechanisms that have been in use in the Internet for many years
(e.g., CUBIC [RFC8312]). Unfairness may also be a result of other
factors, including the round trip time experienced by a flow. ABE
applies only when ECN-marked packets are received, not when packets
are lost, hence use of ABE cannot lead to congestion collapse.

11. Revision Information

XX RFC ED - PLEASE REMOVE THIS SECTION XXX

-12. Corrections from Adam Roach; Benjamin Kaduk; & Ben Campbell

-10. Incorported changes following the Gen-ART review by Russ
Housley. Correction to URL.

-09. Changed to "Following publication of RFC 8311, this document
specifies a sender-side change to TCP:"

-08. Addressed comments from AD review on the document structure,
and relationship to existing RFCs.

-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.

-05. Refined the description of the experiment based on feedback at
IETF-100. Incorporated comments from David Black.

-04. Incorporates review comments from Lawrence Stewart and the
remaining comments from Roland Bless. References are updated.

-03. Several review comments from Roland Bless are addressed.
Consistent terminology and equations. Clarification on the scope of
recommended beta_{ecn} value.

-02. Corrected the equations in Section 3.1. Updated the
affiliations. Lower bound for cwnd is defined. A recommendation for
window-based transport protocols is changed to cover all transport
protocols that implement a congestion control reduction to an ECN
congestion signal. Added text about ABE's FreeBSD mainline kernel
status including a reference to the FreeBSD code review page.
References are updated.

-01. Text improved, mainly incorporating comments from Stuart
Cheshire. The reference to a technical report has been updated to a
published version of the tests [ABE2017]. Used "AQM Mechanism"
throughout in place of other alternatives, and more consistent use of
technical language and clarification on the intended purpose of the
experiments required by EXP status. There was no change to the
technical content.

-00. draft-ietf-tcpm-alternativebackoff-ecn-00 replaces draft-
khademi-tcpm-alternativebackoff-ecn-01. Text describing the nature
of the experiment was added.

Individual draft -01. This I-D now refers to draft-black-tsvwg-ecn-
experimentation-02, which replaces draft-khademi-tsvwg-ecn-
response-00 to make a broader update to RFC 3168 for the sake of
allowing experiments. As including the round-trip time experienced by a result, some flow. ABE
applies only when ECN-marked packets are received, not when packets
are lost. Therefore, use of the motivating and
discussing text that was moved from draft-khademi-alternativebackoff-
ecn-03 ABE cannot lead to draft-khademi-tsvwg-ecn-response-00 has now been re-
inserted here.

Individual draft -00. draft-khademi-tsvwg-ecn-response-00 and draft-
khademi-tcpm-alternativebackoff-ecn-00 replace draft-khademi-
alternativebackoff-ecn-03, following discussion in the TSVWG and TCPM
working groups.

12. congestion collapse.

9. References

12.1.

9.1. Normative References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.

[RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition
of Explicit Congestion Notification (ECN) to IP",
RFC 3168, DOI 10.17487/RFC3168, September 2001,
<https://www.rfc-editor.org/info/rfc3168>.

[RFC5681] Allman, M., Paxson, V., and E. Blanton, "TCP Congestion
Control", RFC 5681, DOI 10.17487/RFC5681, September 2009,
<https://www.rfc-editor.org/info/rfc5681>.

[RFC7567] Baker, F., Ed. and G. Fairhurst, Ed., "IETF
Recommendations Regarding Active Queue Management",
BCP 197, RFC 7567, DOI 10.17487/RFC7567, July 2015,
<https://www.rfc-editor.org/info/rfc7567>.

[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.

[RFC8257] Bensley, S., Thaler, D., Balasubramanian, P., Eggert, L.,
and G. Judd, "Data Center TCP (DCTCP): TCP Congestion
Control for Data Centers", RFC 8257, DOI 10.17487/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>.

12.2.

9.2. Informative References

[ABE-FreeBSD]

[ABE-REVISION]
Stewart, L., "ABE patch review in FreeBSD",
Revision 331214, March 2018, <https://svnweb.freebsd.org/
base?view=revision&revision=331214>.

[ABE2017] Khademi, N., Armitage, G., Welzl, M., Fairhurst, G., Zander, S.,
Fairhurst, G., and D. Ros, "Alternative Backoff: backoff: Achieving
Low Latency
low latency and High Throughput high throughput with ECN and AQM", IFIP
NETWORKING 2017,
Networking Conference and Workshops Stockholm, Sweden,
DOI 10.23919/IFIPNetworking.2017.8264863, June 2017.

[ACC-ECN-FEEDBACK]
Briscoe, B., Kuehlewind, M., and R. Scheffenegger, "More
Accurate ECN Feedback in TCP", Work in Progress,
draft-ietf-tcpm-accurate-ecn-07, July 2018.

[BUFFERBLOAT]
Gettys, J. and K. Nichols, "Bufferbloat: Dark Buffers in
the Internet", ACM Queue Queue, Volume 9, Issue 11,
DOI
10.1145/2063166.2071893;
https://queue.acm.org/detail.cfm?id=2071893", 10.1145/2063166.2071893, November
2011.

[CODEL2012]
Nichols, K. and V. Jacobson, "Controlling Queue Delay",
July 2012, <http://queue.acm.org/detail.cfm?id=2209336>.

[I-D.ietf-tcpm-accurate-ecn]
Briscoe, B., Kuehlewind, M., and R. Scheffenegger, "More
Accurate ECN Feedback in TCP", draft-ietf-tcpm-accurate-
ecn-06 (work in progress), March 2018. 2011,
<https://queue.acm.org/detail.cfm?id=2071893>.

[ICC2002] Kwon, M. and S. Fahmy, "TCP Increase/Decrease Behavior increase/decrease behavior
with Explicit Congestion Notification explicit congestion notification (ECN)", 2002 IEEE
International Conference on Communications Conference
Proceedings, ICC 2002, New York, New York, USA, Cat. No.02CH37333,
DOI 10.1109/ICC.2002.997262, May 2002,
<http://dx.doi.org/10.1109/ICC.2002.997262>.

[RFC8033] Pan, R., Natarajan, P., Baker, F., and G. White,
"Proportional Integral Controller Enhanced (PIE): A
Lightweight Control Scheme to Address the Bufferbloat
Problem", RFC 8033, DOI 10.17487/RFC8033, February 2017,
<https://www.rfc-editor.org/info/rfc8033>.

[RFC8087] Fairhurst, G. and M. Welzl, "The Benefits of Using
Explicit Congestion Notification (ECN)", RFC 8087,
DOI 10.17487/RFC8087, March 2017,
<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>.

Acknowledgements

Authors N. Khademi, M. Welzl, and G. Fairhurst were partly funded by
the European Community under its Seventh Framework Programme through
the Reducing Internet Transport Latency (RITE) project (ICT-317700).
The views expressed are solely those of the authors.

Author G. Armitage performed most of his work on this document while
employed by Swinburne University of Technology, Melbourne, Australia.

The authors would like to thank Stuart Cheshire for many suggestions
when revising this document. They would also like to thank the
following people for their contributions to [ABE2017]: Chamil
Kulatunga, David Ros, Stein Gjessing, and Sebastian Zander. Thanks
also to (in alphabetical order) David Black, Roland Bless, Bob
Briscoe, Markku Kojo, John Leslie, Lawrence Stewart, and the TCPM
Working Group for providing valuable feedback on this document.

Finally, the authors would like to thank everyone who provided
feedback on the congestion control behaviour specified in this
document that was received from the IRTF Internet Congestion Control
Research Group (ICCRG).

Authors' Addresses

Naeem Khademi
University of Oslo
PO Box 1080 Blindern
Oslo N-0316
Norway

Email: naeemk@ifi.uio.no

Michael Welzl
University of Oslo
PO Box 1080 Blindern
Oslo N-0316
Norway

Email: michawe@ifi.uio.no

Grenville Armitage
Netflix Inc.

Email: garmitage@netflix.com

Godred Fairhurst
University of Aberdeen
School of Engineering, Fraser Noble Building
Aberdeen AB24 3UE
UK
United Kingdom

Email: gorry@erg.abdn.ac.uk