One document matched: draft-ietf-tcpm-dctcp-01.xml
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<rfc docName="draft-ietf-tcpm-dctcp-01" ipr="trust200902" category="info">
<front>
<title abbrev='DCTCP'>Datacenter TCP (DCTCP): TCP Congestion Control for Datacenters</title>
<author initials='S.' surname='Bensley' fullname='Stephen Bensley'>
<organization>Microsoft</organization>
<address>
<postal>
<street>One Microsoft Way</street>
<city>Redmond</city>
<region>WA</region>
<code>98052</code>
<country>USA</country>
</postal>
<phone>+1 425 703 5570</phone>
<email>sbens@microsoft.com</email>
</address>
</author>
<author initials='L.' surname='Eggert' fullname='Lars Eggert'>
<organization>NetApp</organization>
<address>
<postal>
<street>Sonnenallee 1</street>
<city>Kirchheim</city>
<code>85551</code>
<country>Germany</country>
</postal>
<phone>+49 151 120 55791</phone>
<email>lars@netapp.com</email>
<uri>http://eggert.org/</uri>
</address>
</author>
<author initials='D.' surname='Thaler' fullname='Dave Thaler'>
<organization>Microsoft</organization>
<address>
<phone>+1 425 703 8835</phone>
<email>dthaler@microsoft.com</email>
</address>
</author>
<author initials='P.' surname='Balasubramanian' fullname='Praveen Balasubramanian'>
<organization>Microsoft</organization>
<address>
<phone>+1 425 538 2782</phone>
<email>pravb@microsoft.com</email>
</address>
</author>
<author initials='G.' surname='Judd' fullname='Glenn Judd'>
<organization>Morgan Stanley</organization>
<address>
<phone>+1 973 979 6481</phone>
<email>glenn.judd@morganstanley.com</email>
</address>
</author>
<date/>
<area>Transport</area>
<keyword>TCP</keyword>
<keyword>ECN</keyword>
<keyword>DCTCP</keyword>
<keyword>congestion control</keyword>
<abstract>
<t> This informational memo describes Datacenter TCP (DCTCP), an improvement to TCP congestion control for datacenter traffic.
DCTCP uses improved Explicit Congestion Notification (ECN) processing to estimate the fraction of bytes that encounter congestion,
rather than simply detecting that some congestion has occurred. DCTCP then scales the TCP congestion window based on this
estimate. This method achieves high burst tolerance, low latency, and high throughput with shallow-buffered switches. This memo also
discusses deployment issues related to the coexistence of DCTCP and conventional TCP, the lack of a negotiating mechanism between
sender and receiver, and presents some possible mitigations.
</t>
</abstract>
</front>
<middle>
<section title='Introduction'>
<t> Large datacenters necessarily need many network switches to interconnect its many servers.
Therefore, a datacenter can greatly reduce its capital expenditure by leveraging low-cost switches. However, such low-cost
switches tend to have limited queue capacities and are thus more susceptible to packet loss due to congestion.
</t>
<t> Network traffic in a datacenter is often a mix of short and long flows, where the short flows require low latencies and
the long flows require high throughputs. Datacenters also experience incast bursts, where many servers send traffic to a
single server at the same time. For example, this traffic pattern is a natural consequence of MapReduce workload: The worker nodes
complete at approximately the same time, and all reply to the master node concurrently.
</t>
<t> These factors place some conflicting demands on the queue occupancy of a switch:
<list style='symbols'>
<t> The queue must be short enough that it does not impose excessive latency on short flows.
</t>
<t> The queue must be long enough to buffer sufficient data for the long flows to saturate the path capacity.
</t>
<t> The queue must be short enough to absorb incast bursts without excessive packet loss.
</t>
</list>
</t>
<t> Standard TCP congestion control <xref target="RFC5681"/> relies on packet loss to detect congestion. This does not meet
the demands described above. First, short flows will start to experience unacceptable latencies before packet loss
occurs. Second, by the time TCP congestion control kicks in on the senders, most of the incast burst has already been dropped.
</t>
<t> <xref target="RFC3168"/> describes a mechanism for using Explicit Congestion Notification (ECN) from the switches for early
detection of congestion, rather than waiting for packet loss to occur. However, this method only detects the presence of
congestion, not its extent. In the presence of mild congestion, the TCP congestion window is reduced too aggressively and this
unnecessarily reduces the throughput of long flows.
</t>
<t> Datacenter TCP (DCTCP) improves traditional ECN processing by estimating the fraction of bytes that
encounter congestion, rather than simply detecting that some congestion has occurred. DCTCP then scales the TCP congestion
window based on this estimate. This method achieves high burst tolerance, low latency, and high throughput with
shallow-buffered switches.
</t>
<t>
It is recommended that DCTCP be deployed in a datacenter environment where the endpoints and the switching fabric are under a single
administrative domain. This protocol is not meant for uncontrolled deployment in the global Internet.
</t>
</section>
<section title="Terminology" anchor="term">
<t>
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in <xref target="RFC2119"/>.
</t>
</section>
<section title='DCTCP Algorithm'>
<t> There are three components involved in the DCTCP algorithm:
<list style='symbols'>
<t> The switches (or other intermediate devices in the network) detect congestion and set the Congestion Encountered (CE)
codepoint in the IP header.
</t>
<t> The receiver echoes the congestion information back to the sender, using the ECN-Echo (ECE) flag in the TCP header.
</t>
<t> The sender computes a congestion estimate and reacts, by reducing the TCP congestion window accordingly (cwnd).
</t>
</list>
</t>
<section title='Marking Congestion on the Switches'>
<t>The switches in a datacenter fabric indicate congestion to the end nodes by setting the CE codepoint in the IP header as specified in Section 5 of <xref target="RFC3168"/>.
For example, the switches may be configured with a congestion threshold. When a packet arrives at a switch and
its queue length is greater than the congestion threshold, the switch sets the CE codepoint in the packet.
For example, Section 3.4 of <xref target="DCTCP10"/> suggests threshold marking with a threshold K > (RTT * C)/7, where C is the sending rate in packets per second.
However, the actual algorithm for marking congestion is an implementation detail of the switch and will generally not be
known to the sender and receiver. Therefore, sender and receiver MUST NOT assume that a particular
marking algorithm is implemented by the switching fabric.
</t>
</section>
<section title='Echoing Congestion Information on the Receiver'>
<t> According to Section 6.1.3 of <xref target="RFC3168"/>, the receiver sets the ECE flag if any of the packets being acknowledged had
the CE code point set. The receiver then continues to set the ECE flag until it receives a packet with the Congestion Window Reduced (CWR)
flag set. However, the DCTCP algorithm requires more detailed congestion information. In particular, the sender must be
able to determine the number of bytes sent that encountered congestion. Thus, the scheme described in <xref target="RFC3168"/> does not
suffice.
</t>
<t> One possible solution is to ACK every packet and set the ECE flag in the ACK if and only if the CE code point was set
in the packet being acknowledged. However, this prevents the use of delayed ACKs, which are an important performance
optimization in datacenters.
</t>
<t>Instead, DCTCP introduces a new Boolean TCP state variable, "DCTCP Congestion Encountered"
(DCTCP.CE), which is initialized to false and stored in the
Transmission Control Block (TCB). When sending an ACK, the ECE flag MUST be set if and only if
DCTCP.CE is true. When receiving packets, the CE codepoint MUST be processed as follows:
<list style='numbers'>
<t> If the CE codepoint is set and DCTCP.CE is false, send an ACK for any previously unacknowledged packets and set
DCTCP.CE to true.
</t>
<t> If the CE codepoint is not set and DCTCP.CE is true, send an ACK for any previously unacknowledged packets and set
DCTCP.CE to false.
</t>
<t> Otherwise, ignore the CE codepoint.
</t>
</list>
</t>
<t> The handling of the "Congestion Window Reduced" (CWR) bit is also exactly as per <xref target="RFC3168"/>
including <xref target="RFC3168-ERRATA3639"/>. That is, on receipt of a segment with both the CE and CWR bits set, CWR is processed first and then
ECE is processed.
</t>
<figure align="center" anchor="dctcp_state_machine_graph" title="ACK generation state machine. DCTCP.CE abbreviated as CE.">
<artwork align="center"><![CDATA[
Send immediate
ACK with ECE=0
.----. .-------------. .---.
Send 1 ACK / v v | | \
for every | .------. .------. | Send 1 ACK
m packets | | CE=0 | | CE=1 | | for every
with ECE=0 | '------' '------' | m packets
\ | | ^ ^ / with ECE=1
'---' '------------' '----'
Send immediate
ACK with ECE=1
]]></artwork>
</figure>
</section>
<section title='Processing Congestion Indications on the Sender' anchor='senderprocessing'>
<t> The sender estimates the fraction of bytes sent that encountered congestion. The current estimate is stored in a new
TCP state variable, DCTCP.Alpha, which is initialized to 1 and MUST be updated as follows:
<list>
<t> DCTCP.Alpha = DCTCP.Alpha * (1 - g) + g * M </t>
</list>
</t>
<t> where
<list style='symbols'>
<t> g is the estimation gain, a real number between 0 and 1. The selection of g is left to the implementation.
See <xref target="implissues"/> for further considerations.
</t>
<t> M is the fraction of bytes sent that encountered congestion during the previous observation window, where the
observation window is chosen to be approximately the Round Trip Time (RTT). In particular, an observation window
ends when all bytes in flight at the beginning of the window have been acknowledged.
</t>
</list>
</t>
<t> In order to update DCTCP.Alpha, the TCP state variables defined in <xref target="RFC0793"/> are used, and
three additional TCP state variables are introduced:
<list style='symbols'>
<t> DCTCP.WindowEnd: The TCP sequence number threshold for beginning a new observation window; initialized to
SND.UNA.
</t>
<t> DCTCP.BytesSent: The number of bytes sent during the current observation window; initialized to zero.
</t>
<t> DCTCP.BytesMarked: The number of bytes sent during the current observation window that encountered congestion; initialized
to zero.
</t>
</list>
</t>
<t> The congestion estimator on the sender MUST process acceptable ACKs as follows:
<list style='numbers'>
<t> Compute the bytes acknowledged (TCP SACK options <xref target="RFC2018"/> are ignored):
<list style='none'>
<t> BytesAcked = SEG.ACK - SND.UNA </t>
</list>
</t>
<t> Update the bytes sent:
<list style='none'>
<t> DCTCP.BytesSent += BytesAcked </t>
</list>
</t>
<t> If the ECE flag is set, update the bytes marked:
<list style='none'>
<t> DCTCP.BytesMarked += BytesAcked </t>
</list>
</t>
<t> If the acknowledgment number is less than or equal to DCTCP.WindowEnd, stop processing. Otherwise,
the end of the observation window has been reached, so proceed to update the congestion estimate as follows:
</t>
<t> Compute the congestion level for the current observation window:
<list style='none'>
<t> M = DCTCP.BytesMarked / DCTCP.BytesSent </t>
</list>
</t>
<t> Update the congestion estimate:
<list style='none'>
<t> DCTCP.Alpha = DCTCP.Alpha * (1 - g) + g * M </t>
</list>
</t>
<t> Determine the end of the next observation window:
<list style='none'>
<t> DCTCP.WindowEnd = SND.NXT </t>
</list>
</t>
<t> Reset the byte counters:
<list style='none'>
<t> DCTCP.BytesSent = DCTCP.BytesMarked = 0 </t>
</list>
</t>
</list>
</t>
<t> Rather than always halving the congestion window as described in <xref target="RFC3168"/>, when the sender receives an
indication of congestion (ECE), the sender MUST update cwnd as follows:
<list>
<t> cwnd = cwnd * (1 - DCTCP.Alpha / 2)
</t>
</list>
</t>
<t> Thus, when no bytes sent experienced congestion, DCTCP.Alpha equals zero, and cwnd is left unchanged. When all sent
bytes experienced congestion, DCTCP.Alpha equals one, and cwnd is reduced by half. Lower levels of congestion will result
in correspondingly smaller reductions to cwnd.
</t>
<t> Just as specified in <xref target="RFC3168"/>, TCP should not react to congestion indications more than once for every
window of data. The setting of the "Congestion Window Reduced" (CWR) bit is also exactly as per <xref target="RFC3168"/>.
</t>
</section>
<section title='Handling of SYN, SYN-ACK, RST Packets'>
<t> <xref target="RFC3168"/> requires that a compliant TCP MUST NOT set ECT on SYN or SYN-ACK packets. <xref target="RFC5562"/>
proposes setting ECT on SYN-ACK packets, but maintains the restriction of no ECT on SYN packets. Both these RFCs prohibit
ECT in SYN packets due to security concerns regarding malicious SYN packets with ECT set. These RFCs, however, are intended
for general Internet use, and do not directly apply to a controlled datacenter environment. The switching fabric can drop TCP
packets that do not have the ECT set in the IP header. If SYN and SYN-ACK packets for DCTCP connections do not have ECT set, they will
be dropped with high probability. For DCTCP connections, the sender SHOULD set ECT for SYN, SYN-ACK and RST packets.
</t>
</section>
</section>
<section title='Implementation Issues' anchor="implissues">
<t> As noted in <xref target='senderprocessing' />, the implementation MUST choose a suitable estimation gain.
<xref target='DCTCP10' /> provides a theoretical basis for selecting the gain. However, it may be more practical to use
experimentation to select a suitable gain for a particular network and workload. The Microsoft implementation of DCTCP
in Windows Server 2012 uses a fixed estimation gain of 1/16.
</t>
<t> The implementation must also decide when to use DCTCP. Datacenter servers may need to communicate with endpoints outside
the datacenter, where DCTCP is unsuitable or unsupported. Thus, a global configuration setting to enable DCTCP will
generally not suffice. DCTCP provides no mechanism for negotiating its use. Thus, there is additional management and configuration overhead
required to ensure that DCTCP is not used with non-DCTCP endpoints.
</t>
<t>Potential solutions rely on either configuration or heuristics. Heuristics need to allow endpoints to individually
enable DCTCP, to ensure a DCTCP sender is always paired with a DCTCP receiver.
One approach is to enable DCTCP based on the IP address of the remote endpoint. Another approach is to
detect connections that transmit within the bounds a datacenter. For example, Microsoft Windows Server 2012 (and later versions) supports automatic
selection of DCTCP if the estimated RTT is less than 10 msec and ECN is successfully negotiated, under the assumption that if the RTT is low, then
the two endpoints are likely in the same datacenter network.
</t>
<t> It is RECOMMENDED that an implementation deal with loss episodes in the same way as conventional TCP. In case of a timeout or
fast retransmit or any change in delay (for delay based congestion control), the cwnd and other state variables like ssthresh must be
changed in the same way that a conventional TCP would have changed them. It would be useful to implement DCTCP as additional actions on
top of an existing congestion control algorithm like NewReno. The DCTCP implementation MAY also allow configuration of resetting the
value of DCTCP.Alpha as part of processing any loss episodes.
</t>
<t> To prevent incast throughput collapse, the minimum RTO (MinRTO) used by TCP should be lowered significantly. The default value of
MinRTO in Windows is 300 msec, which is much greater than the maximum latencies inside a datacenter. In Microsoft Windows Server 2012 (and later), the
MinRTO value is configurable, allowing values as low as 10 msec on a per-subnet or per-port basis (or even globally.) A lower MinRTO value
requires a correspondingly lower delayed ACK timeout on the receiver. It is RECOMMENDED that an implementation allow configuration of
lower timeouts for DCTCP connections.
</t>
<t> In the same vein, it is also RECOMMENDED that an implementation allow configuration of restarting the congestion window (cwnd) of
idle DCTCP connections as described in <xref target="RFC5681"/>, since network conditions can change rapidly in datacenters.
</t>
<t> <xref target="RFC3168"/> forbids the ECN-marking of pure ACK packets, because of the inability of TCP to mitigate ACK-path
congestion and protocol-wise preferential treatment by routers. However, dropping pure ACKs - rather than ECN marking them - has
disadvantages for typical datacenter traffic patterns. Because of the prevalence of bursty traffic patterns that feature
transient congestion, dropping of ACKs causes subsequent retransmissions. It is RECOMMENDED that an implementation provide a configuration
knob that forces ECT to be set on pure ACKs.
</t>
<t> The DCTCP.Alpha calculation as per the formula in <xref target='senderprocessing' /> involves fractions. An efficient kernel implementation
MAY scale the DCTCP.Alpha value for efficient computation using shift operations. For example, if the implementation chooses
g as 1/16, multiplications of DCTCP.Alpha by g become right-shifts by 4.
A scaling implementation SHOULD ensure that DCTCP.Alpha is able to reach zero once it falls below the smallest shifted value (16 in the above example).
At the other extreme, a scaled update MUST also ensure DCTCP.Alpha does not exceed the scaling factor, which would be equivalent to greater than
100% congestion. So, DCTCP.Alpha MUST be clamped after an update.
</t>
<t> This results in the following computations replacing steps 5 and 6 in <xref target='senderprocessing' />, where SCF is the chosen
scaling factor (65536 in the example) and SHF is the shift factor (4 in the example):
<list style='numbers'>
<t> Compute the congestion level for the current observation window:
<list style='none'>
<t> ScaledM = SCF * DCTCP.BytesMarked / DCTCP.BytesSent </t>
</list>
</t>
<t> Update the congestion estimate:
<list style='none'>
<t> if (DCTCP.Alpha >> SHF) == 0 then DCTCP.Alpha = 0 </t>
</list>
<list style='none'>
<t> DCTCP.Alpha += (ScaledM >> SHF) - (DCTCP.Alpha >> SHF) </t>
</list>
<list style='none'>
<t> if DCTCP.Alpha > SCF then DCTCP.Alpha = SCF </t>
</list>
</t>
</list>
</t>
</section>
<section title='Deployment Issues'>
<t> DCTCP and conventional TCP congestion control do not coexist well in the same network. In DCTCP, the marking threshold is set to a very low
value to reduce queueing delay, and a relatively small amount of congestion will exceed the marking threshold. During such periods
of congestion, conventional TCP will suffer packet loss and quickly and drastically reduce cwnd. DCTCP, on the other hand, will use the fraction
of marked packets to reduce cwnd more gradually. Thus, the rate reduction in DCTCP will be much slower than that of conventional TCP, and DCTCP traffic
will gain a larger share of the capacity compared to conventional TCP traffic traversing the same path. If the traffic in the datacenter is a mix of conventional TCP
and DCTCP, it is RECOMMENDED that DCTCP traffic be segregated from conventional TCP traffic. <xref target='MORGANSTANLEY' /> describes
a deployment that uses the IP DSCP bits to segregate the network such that AQM is applied to DCTCP traffic, whereas TCP traffic is managed via drop-tail queueing.
</t>
<t> Today's commodity switches allow configuration of different marking/drop profiles for non-TCP and non-IP packets. Non-TCP and non-IP
packets should be able to pass through such switches, unless they really run out of buffer space. If the datacenter traffic consists of
such traffic (including UDP), one possible mitigation would be to mark IP packets as ECT even when there is no transport that is reacting
to the marking.
</t>
<t> Since DCTCP relies on congestion marking by the switches, DCTCP can only be deployed in datacenters where the entire network
infrastructure supports ECN. The switches may also support configuration of the congestion threshold used for marking.
The proposed parameterization can be configured with switches that implement RED. <xref target='DCTCP10' /> provides a theoretical
basis for selecting the congestion threshold, but as with the estimation gain, it may be more practical to rely on experimentation or
simply to use the default configuration of the device. DCTCP will degrade to loss-based congestion control when transiting a
congested drop-tail link.
</t>
<t> DCTCP requires changes on both the sender and the receiver, so both endpoints must support DCTCP. Furthermore, DCTCP
provides no mechanism for negotiating its use, so both endpoints must be configured through some out-of-band mechanism to
use DCTCP. A variant of DCTCP that can be deployed unilaterally and only requires standard ECN behavior has been described
in <xref target="ODCTCP"/><xref target="BSDCAN"/>, but requires additional experimental evaluation.
</t>
</section>
<section title='Known Issues'>
<t> DCTCP relies on the sender's ability to reconstruct the stream of CE codepoints received by the remote endpoint. To
accomplish this, DCTCP avoids using a single ACK packet to acknowledge segments received both with and without the CE
codepoint set. However, if one or more ACK packets are dropped, it is possible that a subsequent ACK will cumulatively acknowledge
a mix of CE and non-CE segments. This will, of course, result in a less accurate congestion estimate. There are some potential considerations:
<list style="symbols">
<t> Even with an inaccurate congestion estimate, DCTCP may still perform better than <xref target="RFC3168"/>.
</t>
<t> If the estimation gain is small relative to the packet loss rate, the estimate may not be too inaccurate.
</t>
<t> If packet loss mostly occurs under heavy congestion, most drops will occur during an unbroken string of CE packets,
and the estimate will be unaffected.
</t>
</list>
However, the effect of packet drops on DCTCP under real world conditions has not been analyzed.
</t>
<t> DCTCP provides no mechanism for negotiating its use. The effect of using DCTCP with a standard ECN endpoint
has been analyzed in <xref target="ODCTCP"/><xref target="BSDCAN"/>. Furthermore, it is possible that other implementations may also modify
<xref target="RFC3168"/> behavior without negotiation, causing further interoperability issues.
</t>
<t> Much like standard TCP, DCTCP is biased against flows with longer RTTs. A method for improving the fairness of DCTCP
has been proposed in <xref target="ADCTCP"/>, but requires additional experimental evaluation.
</t>
</section>
<section title='Implementation Status'>
<t> This section documents the implementation status of the specification in this document, as recommended by <xref target="RFC6982"/>.
</t>
<t> This document describes DCTCP as implemented in Microsoft Windows Server 2012. Since publication of the first versions of this
document, the Linux <xref target="LINUX"/> and FreeBSD <xref target="FREEBSD"/> operating systems have also implemented support for DCTCP in
a way that is believed to follow this document.
</t>
</section>
<section title='Security Considerations'>
<t> DCTCP enhances ECN and thus inherits the security considerations discussed in <xref target="RFC3168"/>. The processing
changes introduced by DCTCP do not exacerbate these considerations or introduce new ones. In particular, with either
algorithm, the network infrastructure or the remote endpoint can falsely report congestion and thus cause the sender to
reduce cwnd. However, this is no worse than what can be achieved by simply dropping packets.
</t>
</section>
<section title='IANA Considerations'>
<t> This document has no actions for IANA.
</t>
</section>
<section title='Acknowledgements'>
<t> The DCTCP algorithm was originally proposed and analyzed in <xref target="DCTCP10"/> by Mohammad Alizadeh,
Albert Greenberg, Dave Maltz, Jitu Padhye, Parveen Patel, Balaji Prabhakar, Sudipta Sengupta, and
Murari Sridharan.
</t>
<t> We would like to thank Andrew Shewmaker for identifying the problem of clamping DCTCP.Alpha and proposing a solution for it.
</t>
<t>
Lars Eggert has received funding from the European Union's Horizon 2020 research and innovation program 2014-2018 under grant agreement No. 644866 ("SSICLOPS").
This document reflects only the authors' views and the European Commission is not responsible for any use that may be made of the information it contains.
</t>
</section>
</middle>
<back>
<references title='Normative References'>
&rfc0793;
&rfc2018;
&rfc2119;
&rfc3168;
</references>
<references title='Informative References'>
&rfc5681;
&rfc5562;
&rfc6982;
<reference anchor='DCTCP10' target='http://dl.acm.org/citation.cfm?doid=1851182.1851192'>
<front>
<title>Data Center TCP (DCTCP)</title>
<author initials="M." surname="Alizadeh" fullname="Mohammad Alizadeh">
<organization abbrev="Stanford"> Stanford University </organization>
<address>
<email> alizade@stanford.edu </email>
</address>
</author>
<author initials="A." surname="Greenberg" fullname="Albert Greenberg">
<organization abbrev="MSR"> Microsoft Research </organization>
<address>
<email> albert@microsoft.com </email>
</address>
</author>
<author initials="D.A." surname="Maltz" fullname="David A. Maltz">
<organization abbrev="MSR"> Microsoft Research </organization>
<address>
<email> dmaltz@microsoft.com </email>
</address>
</author>
<author initials="J." surname="Padhye" fullname="Jitendra Padhye">
<organization abbrev="MSR"> Microsoft Research </organization>
<address>
<email> padhye@microsoft.com </email>
</address>
</author>
<author initials="P." surname="Patel" fullname="Parveen Patel">
<organization abbrev="MSR"> Microsoft Research </organization>
<address>
<email> parveenp@microsoft.com </email>
</address>
</author>
<author initials="B." surname="Prabhakar" fullname="Balaji Prabhakar">
<organization abbrev="Stanford"> Stanford University </organization>
<address>
<email> balaji@stanford.edu </email>
</address>
</author>
<author initials="S." surname="Sengupta" fullname="Sudipta Sengupta">
<organization abbrev="MSR"> Microsoft Research </organization>
<address>
<email> sudipta@microsoft.com </email>
</address>
</author>
<author initials="M." surname="Sridharan" fullname="Murari Sridharan">
<organization abbrev="MSR"> Microsoft Research </organization>
<address>
<email> muraris@microsoft.com </email>
</address>
</author>
<date year="2010" month="August"/>
</front>
<seriesInfo name="DOI" value="10.1145/1851182.1851192"/>
<seriesInfo name="" value="Proc. ACM SIGCOMM 2010 Conference (SIGCOMM 10)"/>
</reference>
<reference anchor="ODCTCP" target="http://eggert.org/students/kato-thesis.pdf">
<front>
<title>Improving Transmission Performance with One-Sided Datacenter TCP</title>
<author initials="M." surname="Kato">
<organization />
</author>
<date year="2014"/>
</front>
<seriesInfo name="" value="M.S. Thesis, Keio University"/>
</reference>
<reference anchor="BSDCAN" target="https://www.bsdcan.org/2015/schedule/events/559.en.html">
<front>
<title>Extensions to FreeBSD Datacenter TCP for Incremental Deployment Support</title>
<author initials="M." surname="Kato">
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<author initials="L." surname="Eggert">
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<author initials="A." surname="Zimmermann">
<organization />
</author>
<author initials="R." surname="van Meter">
<organization />
</author>
<author initials="H." surname="Tokuda">
<organization />
</author>
<date month="June" year="2015"/>
</front>
<seriesInfo name="" value="BSDCan 2015"/>
</reference>
<reference anchor="ADCTCP" target="https://dl.acm.org/citation.cfm?id=1993753">
<front>
<title> Analysis of DCTCP: Stability, Convergence, and Fairness </title>
<author initials="M." surname="Alizadeh" fullname="Mohammad Alizadeh">
<organization abbrev="Stanford"> Stanford University </organization>
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</author>
<author initials="A." surname="Javanmard" fullname="Adel Javanmard">
<organization abbrev="Stanford"> Stanford University </organization>
<address>
<email> adelj@stanford.edu </email>
</address>
</author>
<author initials="B." surname="Prabhakar" fullname="Balaji Prabhakar">
<organization abbrev="Stanford"> Stanford University </organization>
<address>
<email> balaji@stanford.edu </email>
</address>
</author>
<date year="2011" month="June"/>
</front>
<seriesInfo name="DOI" value="10.1145/1993744.1993753"/>
<seriesInfo name="" value="Proc. ACM SIGMETRICS Joint International Conference on Measurement and Modeling of Computer Systems (SIGMETRICS 11)"/>
</reference>
<reference anchor="LINUX" target="https://git.kernel.org/cgit/linux/kernel/git/davem/net-next.git/commit/?id=e3118e8359bb7c59555aca60c725106e6d78c5ce">
<front>
<title>Linux DCTCP patch</title>
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<organization />
</author>
<author initials="F." surname="Westphal">
<organization />
</author>
<date year="2014"/>
</front>
</reference>
<reference anchor="FREEBSD" target="https://github.com/freebsd/freebsd/commit/8ad879445281027858a7fa706d13e458095b595f">
<front>
<title>DCTCP (Data Center TCP) implementation</title>
<author initials="M." surname="Kato">
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<organization />
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<date year="2015"/>
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</reference>
<reference anchor="MORGANSTANLEY" target="https://www.usenix.org/conference/nsdi15/technical-sessions/presentation/judd">
<front>
<title>Attaining the Promise and Avoiding the Pitfalls of TCP in the Datacenter</title>
<author initials="G." surname="Judd" fullname="Glenn Judd">
<organization abbrev="MS"> Morgan Stanley </organization>
<address>
<email> glenn.judd@morganstanley.com </email>
</address>
</author>
<date month="May" year="2015"/>
</front>
<seriesInfo name="" value="Proc. 12th USENIX Symposium on Networked Systems Design and Implementation (NSDI 15)"/>
</reference>
<reference anchor="RFC3168-ERRATA3639" target="http://www.rfc-editor.org/errata_search.php?rfc=3168&eid=3639">
<front>
<title>RFC3168 Errata ID 3639</title>
<author initials="R." surname="Scheffenegger">
<organization />
</author>
<date year="2013"/>
</front>
</reference>
</references>
</back>
</rfc>
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