TCP Maintenance and Minor Extensions (TCPM) WG I. Rhee
Internet-Draft NCSU
Intended status: Informational L. Xu
Expires: August 8, 2017 UNL
S. Ha
Colorado
A. Zimmermann
L. Eggert
NetApp
R. Scheffenegger
February 4, 2017
CUBIC for Fast Long-Distance Networks
draft-ietf-tcpm-cubic-04
Abstract
CUBIC is an extension to the current TCP standards. The protocol
differs from the current TCP standards only in the congestion window
adjustment function in the sender side. In particular, it uses a
cubic function instead of a linear window increase function of the
current TCP standards to improve scalability and stability under fast
and long distance networks. CUBIC and its predecessor algorithm have
been adopted as default by Linux and have been used for many years.
This document provides a specification of CUBIC to enable third party
implementation and to solicit the community feedback through
experimentation on the performance of CUBIC.
Status of This Memo
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This Internet-Draft will expire on August 8, 2017.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Design principle of CUBIC . . . . . . . . . . . . . . . . . . 4
4. CUBIC Congestion Control . . . . . . . . . . . . . . . . . . 5
4.1. Window growth function . . . . . . . . . . . . . . . . . 6
4.2. TCP-friendly region . . . . . . . . . . . . . . . . . . . 7
4.3. Concave region . . . . . . . . . . . . . . . . . . . . . 7
4.4. Convex region . . . . . . . . . . . . . . . . . . . . . . 7
4.5. Multiplicative decrease . . . . . . . . . . . . . . . . . 8
4.6. Fast convergence . . . . . . . . . . . . . . . . . . . . 8
4.7. Timeout . . . . . . . . . . . . . . . . . . . . . . . . . 9
5. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . 9
5.1. Fairness to standard TCP . . . . . . . . . . . . . . . . 9
5.2. Using Spare Capacity . . . . . . . . . . . . . . . . . . 11
5.3. Difficult Environments . . . . . . . . . . . . . . . . . 12
5.4. Investigating a Range of Environments . . . . . . . . . . 12
5.5. Protection against Congestion Collapse . . . . . . . . . 12
5.6. Fairness within the Alternative Congestion Control
Algorithm. . . . . . . . . . . . . . . . . . . . . . . . 12
5.7. Performance with Misbehaving Nodes and Outside Attackers 12
5.8. Behavior for Application-Limited Flows . . . . . . . . . 12
5.9. Responses to Sudden or Transient Events . . . . . . . . . 13
5.10. Incremental Deployment . . . . . . . . . . . . . . . . . 13
6. Security Considerations . . . . . . . . . . . . . . . . . . . 13
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
9.1. Normative References . . . . . . . . . . . . . . . . . . 13
9.2. Informative References . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
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1. Introduction
The low utilization problem of TCP in fast long-distance networks is
well documented in [K03][RFC3649]. This problem arises from a slow
increase of congestion window following a congestion event in a
network with a large bandwidth delay product (BDP). Our experience
[HKLRX06] indicates that this problem is frequently observed even in
the range of congestion window sizes over several hundreds of packets
(each packet is sized around 1000 bytes) especially under a network
path with over 100ms round-trip times (RTTs). This problem is
equally applicable to all Reno style TCP standards and their
variants, including TCP-RENO [RFC5681], TCP-NewReno [RFC6582], TCP-
SACK [RFC2018], SCTP [RFC4960], TFRC [RFC5348] that use the same
linear increase function for window growth, which we refer to
collectively as Standard TCP below.
CUBIC [HRX08] is a modification to the congestion control mechanism
of Standard TCP, in particular, to the window increase function of
Standard TCP senders, to remedy this problem. Specifically, it uses
a cubic function instead of a linear window increase function of the
Standrad TCP to improve scalability and stability under fast and long
distance networks.
BIC-TCP, a predecessor of CUBIC, has been selected as default TCP
congestion control algorithm by Linux in the year 2005 and been used
for several years by the Internet community at large. CUBIC uses a
similar window growth function as BIC-TCP and is designed to be less
aggressive and fairer to TCP in bandwidth usage than BIC-TCP while
maintaining the strengths of BIC-TCP such as stability, window
scalability and RTT fairness. CUBIC has already been deployed
globally by Linux. Through extensive testing in various Internet
scenarios, we believe that CUBIC is safe for testing and deployment
in the global Internet.
In the ensuing sections, we first brefly explain the design principle
of CUBIC, then provide the exact specification of CUBIC, and finally
discuss the safety features of CUBIC following the guidelines
specified in [RFC5033].
2. Conventions
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 [RFC2119].
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3. Design principle of CUBIC
CUBIC [HRX08] uses a cubic window increase function in terms of the
elapsed time from the last congestion event. While most alternative
algorithms to Standard TCP uses a convex increase function where
during congestion avoidance the window increment is always
increasing, CUBIC uses both the concave and convex profiles of a
cubic function for window increase. After a window reduction
following a loss event detected by duplicate ACKs, it registers the
window size where it got the loss event as W_max and performs a
multiplicative decrease of congestion window and the regular fast
recovery and retransmit of Standard TCP. After it enters into
congestion avoidance from fast recovery, it starts to increase the
window using the concave profile of the cubic function. The cubic
function is set to have its plateau at W_max so the concave growth
continues until the window size becomes W_max. After that, the cubic
function turns into a convex profile and the convex window growth
begins. This style of window adjustment (concave and then convex)
improves protocol and network stability while maintaining high
network utilization [CEHRX07]. This is because the window size
remains almost constant, forming a plateau around W_max where network
utilization is deemed highest and under steady state, most window
size samples of CUBIC are close to W_max, thus promoting high network
utilization and protocol stability. Note that protocols with convex
increase functions have the maximum increments around W_max and
introduces a large number of packet bursts around the saturation
point of the network, likely causing frequent global loss
synchronizations.
Another notable feature of CUBIC is that its window increase rate is
mostly independent of RTT, and follows a (cubic) function of the
elapsed time from the beginning of congestion avoidance. This
feature promotes per-flow fairness to Standard TCP as well as RTT-
fairness. Note that Standard TCP performs well under short RTT and
small bandwidth (or small BDP) networks. Only in a large long RTT
and large bandwidth (or large BDP) networks, it has the scalability
problem. An alternative protocol to Standard TCP designed to be
friendly to Standard TCP at a per-flow basis must operate to increase
its window much less aggressively in small BDP networks than in large
BDP networks. In CUBIC, its window growth rate is slowest around the
inflection point of the cubic function and this function does not
depend on RTT. In a smaller BDP network where Standard TCP flows are
working well, the absolute amount of the window decrease at a loss
event is always smaller because of the multiplicative decrease.
Therefore, in CUBIC, the starting window size after a loss event from
which the window starts to increase, is smaller in a smaller BDP
network, thus falling nearer to the plateau of the cubic function
where the growth rate is slowest. By setting appropriate values of
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the cubic function parameters, CUBIC sets its growth rate always no
faster than Standard TCP around its inflection point. When the cubic
function grows slower than the window of Standard TCP, CUBIC simply
follows the window size of Standard TCP to ensure fairness to
Standard TCP in a small BDP network. We call this region where CUBIC
behaves like Standard TCP, the TCP-friendly region.
CUBIC maintains the same window growth rate independent of RTTs
outside of the TCP-friendly region, and flows with different RTTs
have the similar window sizes under steady state when they operate
outside the TCP-friendly region. This ensures CUBIC flows with
different RTTs to have their bandwidth shares (approximately, window/
RTT) linearly proportional to the inverse of their RTT ratio (the
longer RTT, the smaller the share). This behavior is the same as
that of Standard TCP under high statistical multiplexing environments
where packet losses are independent of individual flow rates.
However, under low statistical multiplexing environments, the
bandwidth share ratio of Standard TCP flows with different RTTs is
squarely proportional to the inverse of their RTT ratio [XHR04].
CUBIC always ensures the linear ratio independent of the levels of
statistical multiplexing. This is an improvement over Standard TCP.
While there is no consensus on a particular bandwidth share ratios of
different RTT flows, we believe that under wired Internet, use of the
linear share notion seems more reasonable than equal share or a
higher order shares. HTCP [LS08] currently uses the equal share.
CUBIC sets the multiplicative window decrease factor to 0.7 while
Standard TCP uses 0.5. While this improves the scalability of the
protocol, a side effect of this decision is slower convergence
especially under low statistical multiplexing environments. This
design choice is following the observation that the author of HSTCP
[RFC3649] has made along with other researchers (e.g., [GV02]): the
current Internet becomes more asynchronous with less frequent loss
synchronizations with high statistical multiplexing. Under this
environment, even strict Multiplicative-Increase Multiplicative-
Decrease (MIMD) can converge. CUBIC flows with the same RTT always
converge to the same share of bandwidth independent of statistical
multiplexing, thus achieving intra-protocol fairness. We also find
that under the environments with sufficient statistical multiplexing,
the convergence speed of CUBIC flows is reasonable.
4. CUBIC Congestion Control
The unit of all window sizes in this document is segments of the
maximum segment size (MSS), and the unit of all times is seconds.
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4.1. Window growth function
CUBIC maintains the acknowledgment (ACK) clocking of Standard TCP by
increasing congestion window only at the reception of ACK. The
protocol does not make any change to the fast recovery and retransmit
of TCP, such as TCP-NewReno [RFC6582] and TCP-SACK [RFC2018]. During
congestion avoidance after fast recovery, CUBIC changes the window
update algorithm of Standard TCP. Suppose that W_max is the window
size before the window is reduced in the last fast retransmit and
recovery.
The window growth function of CUBIC uses the following function:
W_cubic(t) = C*(t-K)^3 + W_max (Eq. 1)
where C is a constant fixed to determine the aggressiveness of window
growth in high BDP networks, t is the elapsed time from the last
window reduction that is measured right after the fast recovery in
response to duplicate ACKs or after the congestion window reduction
in response to ECN-Echo ACKs, and K is the time period that the above
function takes to increase the current window size to W_max if there
is no further loss event and is calculated by using the following
equation:
K = cubic_root(W_max*(1-beta_cubic)/C) (Eq. 2)
where beta_cubic is the CUBIC multiplication decrease factor, that
is, when a packet loss detected by duplicate ACKs or a network
congestion detected by ECN-Echo ACKs occurs, CUBIC reduces its
current window cwnd to W_cubic(0)=W_max*beta_cubic. We discuss how
we set C in the next Section in more details.
Upon receiving an ACK during congestion avoidance, CUBIC computes the
window growth rate during the next RTT period using Eq. 1. It sets
W_cubic(t+RTT) as the candidate target value of congestion window,
where RTT is the weithed average RTT calculated by the standard TCP.
Depending on the value of the current window size cwnd, CUBIC runs in
three different modes. First, if cwnd is less than the window size
that Standard TCP would reach at time t after the last loss event,
then CUBIC is in the TCP friendly region (we describe below how to
determine this window size of Standard TCP in term of time t).
Otherwise, if cwnd is less than W_max, then CUBIC is the concave
region, and if cwnd is larger than W_max, CUBIC is in the convex
region. Below, we describe the exact actions taken by CUBIC in each
region.
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4.2. TCP-friendly region
Standard TCP performs well in certain types of networks, for example,
under short RTT and small bandwidth (or small BDP) networks. In
these networks, we use the TCP-friendly region to ensure that CUBIC
achieves at least the same throughput as the standard TCP.
When receiving an ACK in congestion avoidance, we first check whether
the protocol is in the TCP region or not. This is done by estimating
the average rate of the Standard TCP using a simple analysis
described in [FHP00]. It considers the Standard TCP as a special
case of an Additive Increase and Multiplicative Decrease algorithm
(AIMD), which has an additive factor alpha_aimd and a multiplicative
factor beta_aimd with the following function:
AVG_W_aimd = [ alpha_aimd * (1+beta_aimd) /
(2*(1-beta_aimd)*p) ]^0.5 (Eq. 3)
By the same analysis, the average window size of Standard TCP is
(1.5/p)^0.5, as the Standard TCP is a special case of AIMD with
alpha_aimd=1 and beta_aimd=0.5. Thus, for Eq. 3 to be the same as
that of Standard TCP, alpha_aimd must be equal to
3*(1-beta_aimd)/(1+beta_aimd). As AIMD increases its window by
alpha_aimd per RTT, we can get the window size of AIMD in terms of
the elapsed time t as follows:
W_aimd(t) = W_max*beta_aimd +
[3*(1-beta_aimd)/(1+beta_aimd)] * (t/RTT) (Eq. 4)
If W_cubic(t) is less than W_aimd(t), then the protocol is in the TCP
friendly region and cwnd SHOULD be set to W_aimd(t) at each reception
of ACK.
4.3. Concave region
When receiving an ACK in congestion avoidance, if the protocol is not
in the TCP-friendly region and cwnd is less than W_max, then the
protocol is in the concave region. In this region, cwnd MUST be
incremented by (W_cubic(t+RTT) - cwnd)/cwnd for each received ACK,
where W_cubic(t+RTT) is calculated using Eq. 1.
4.4. Convex region
When the current window size of CUBIC is larger than W_max, it passes
the plateau of the cubic function after which CUBIC follows the
convex profile of the cubic function. Since cwnd is larger than the
previous saturation point W_max, this indicates that the network
conditions might have been perturbed since the last loss event,
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possibly implying more available bandwidth after some flow
departures. Since the Internet is highly asynchronous, some amount
of perturbation is always possible without causing a major change in
available bandwidth. In this phase, CUBIC is being very careful by
very slowly increasing its window size. The convex profile ensures
that the window increases very slowly at the beginning and gradually
increases its growth rate. We also call this phase as the maximum
probing phase since CUBIC is searching for a new W_max. In this
region, cwnd MUST be incremented by (W_cubic(t+RTT) - cwnd)/cwnd for
each received ACK, where W_cubic(t+RTT) is calculated using Eq. 1.
4.5. Multiplicative decrease
When a packet loss detected by duplicate ACKs or a network congestion
detected by ECN-Echo ACKs occurs, CUBIC updates its W_max, cwnd, and
ssthresh (slow start threshold) as follows. Parameter beta_cubic
SHOULD be set to 0.7.
W_max = cwnd; // save window size before reduction
ssthresh = cwnd * beta_cubic; // new slow start threshold
cwnd = cwnd * beta_cubic; // window reduction
A side effect of setting beta_cubic to a bigger value than 0.5 is
slower convergence. We believe that while a more adaptive setting of
beta_cubic could result in faster convergence, it will make the
analysis of the protocol much harder. This adaptive adjustment of
beta_cubic is an item for the next version of CUBIC.
4.6. Fast convergence
To improve the convergence speed of CUBIC, we add a heuristic in the
protocol. When a new flow joins the network, existing flows in the
network need to give up their bandwidth shares to allow the flow some
room for growth if the existing flows have been using all the
bandwidth of the network. To increase this release of bandwidth by
existing flows, the following mechanism called fast convergence
SHOULD be implemented.
With fast convergence, when a loss event occurs, before a window
reduction of congestion window, a flow remembers the last value of
W_max before it updates W_max for the current loss event. Let us
call the last value of W_max to be W_last_max.
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if (W_max < W_last_max){ // check downward trend
W_last_max = W_max; // remember the last W_max
W_max = W_max*(1+beta_cubic)/2; // further reduce W_max
} else { // check upward trend
W_last_max = W_max // remember the last W_max
}
This allows W_max to be slightly less than the original W_max. Since
flows spend most of time around their W_max, flows with larger
bandwidth shares tend to spend more time around the plateau allowing
more time for flows with smaller shares to increase their windows.
4.7. Timeout
In case of timeout, CUBIC follows the standard TCP to reduce cwnd,
but sets ssthresh using beta_cubic (same as in Section 4.5).
5. Discussion
In this section, we further discuss the safety features of CUBIC
following the guidelines specified in [RFC5033].
With a deterministic loss model where the number of packets between
two successive lost events is always 1/p, CUBIC always operates with
the concave window profile which greatly simplifies the performance
analysis of CUBIC. The average window size of CUBIC can be obtained
by the following function:
AVG_W_cubic = [C*(3+beta_cubic)/(4*(1-beta_cubic))]^0.25 *
(RTT^0.75) / (p^0.75) (Eq. 5)
With beta_cubic set to 0.7, the above formula is reduced to:
AVG_W_cubic = (C*3.7/1.2)^0.25 * (RTT^0.75) / (p^0.75) (Eq. 6)
We will determine the value of C in the following subsection using
Eq. 6.
5.1. Fairness to standard TCP
In environments where standard TCP is able to make reasonable use of
the available bandwidth, CUBIC does not significantly change this
state.
Standard TCP performs well in the following two types of networks:
1. networks with a small bandwidth-delay product (BDP)
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2. networks with a short RTT, but not necessarily a small BDP
CUBIC is designed to behave very similarly to standard TCP in the
above two types of networks. The following two tables show the
average window size of standard TCP, HSTCP, and CUBIC. The average
window size of standard TCP and HSTCP is from [RFC3649]. The average
window size of CUBIC is calculated by using Eq. 6 and CUBIC TCP
friendly mode for three different values of C.
+----------+-------+--------+-------------+-------------+-----------+
| Loss | TCP | HSTCP | CUBIC | CUBIC | CUBIC |
| Rate P | | | (C=0.04) | (C=0.4) | (C=4) |
+----------+-------+--------+-------------+-------------+-----------+
| 10^-2 | 12 | 12 | 12 | 12 | 12 |
| 10^-3 | 38 | 38 | 38 | 38 | 59 |
| 10^-4 | 120 | 263 | 120 | 187 | 333 |
| 10^-5 | 379 | 1795 | 593 | 1054 | 1874 |
| 10^-6 | 1200 | 12279 | 3332 | 5926 | 10538 |
| 10^-7 | 3795 | 83981 | 18740 | 33325 | 59261 |
| 10^-8 | 12000 | 574356 | 105383 | 187400 | 333250 |
+----------+-------+--------+-------------+-------------+-----------+
Response function of standard TCP, HSTCP, and CUBIC in networks with
RTT = 0.1 seconds. The average window size is in MSS-sized segments.
Table 1
+--------+-----------+-----------+------------+-----------+---------+
| Loss | Average | Average | CUBIC | CUBIC | CUBIC |
| Rate P | TCP W | HSTCP W | (C=0.04) | (C=0.4) | (C=4) |
+--------+-----------+-----------+------------+-----------+---------+
| 10^-2 | 12 | 12 | 12 | 12 | 12 |
| 10^-3 | 38 | 38 | 38 | 38 | 38 |
| 10^-4 | 120 | 263 | 120 | 120 | 120 |
| 10^-5 | 379 | 1795 | 379 | 379 | 379 |
| 10^-6 | 1200 | 12279 | 1200 | 1200 | 1874 |
| 10^-7 | 3795 | 83981 | 3795 | 5926 | 10538 |
| 10^-8 | 12000 | 574356 | 18740 | 33325 | 59261 |
+--------+-----------+-----------+------------+-----------+---------+
Response function of standard TCP, HSTCP, and CUBIC in networks with
RTT = 0.01 seconds. The average window size is in MSS-sized
segments.
Table 2
Both tables show that CUBIC with any of these three C values is more
friendly to TCP than HSTCP, especially in networks with a short RTT
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where TCP performs reasonably well. For example, in a network with
RTT = 0.01 seconds and p=10^-6, TCP has an average window of 1200
packets. If the packet size is 1500 bytes, then TCP can achieve an
average rate of 1.44 Gbps. In this case, CUBIC with C=0.04 or C=0.4
achieves exactly the same rate as Standard TCP, whereas HSTCP is
about ten times more aggressive than Standard TCP.
We can see that C determines the aggressiveness of CUBIC in competing
with other protocols for the bandwidth. CUBIC is more friendly to
the Standard TCP, if the value of C is lower. However, we do not
recommend to set C to a very low value like 0.04, since CUBIC with a
low C cannot efficiently use the bandwidth in long RTT and high
bandwidth networks. Based on these observations, we find C=0.4 gives
a good balance between TCP-friendliness and aggressiveness of window
growth. Therefore, C SHOULD be set to 0.4. With C set to 0.4, Eq. 6
is reduced to:
AVG_W_cubic = 1.054 * (RTT^0.75) / (p^0.75) (Eq. 7)
Eq. 7 is then used in the next subsection to show the scalability of
CUBIC.
5.2. Using Spare Capacity
CUBIC uses a more aggressive window growth function than Standard TCP
under long RTT and high bandwidth networks.
The following table shows that to achieve 10Gbps rate, standard TCP
requires a packet loss rate of 2.0e-10, while CUBIC requires a packet
loss rate of 2.9e-8.
+------------------+-----------+---------+---------+---------+
| Throughput(Mbps) | Average W | TCP P | HSTCP P | CUBIC P |
+------------------+-----------+---------+---------+---------+
| 1 | 8.3 | 2.0e-2 | 2.0e-2 | 2.0e-2 |
| 10 | 83.3 | 2.0e-4 | 3.9e-4 | 2.9e-4 |
| 100 | 833.3 | 2.0e-6 | 2.5e-5 | 1.4e-5 |
| 1000 | 8333.3 | 2.0e-8 | 1.5e-6 | 6.3e-7 |
| 10000 | 83333.3 | 2.0e-10 | 1.0e-7 | 2.9e-8 |
+------------------+-----------+---------+---------+---------+
Required packet loss rate for Standard TCP, HSTCP, and CUBIC to
achieve a certain throughput. We use 1500-byte packets and an RTT of
0.1 seconds.
Table 3
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Our test results in [HKLRX06] indicate that CUBIC uses the spare
bandwidth left unused by existing Standard TCP flows in the same
bottleneck link without taking away much bandwidth from the existing
flows.
5.3. Difficult Environments
CUBIC is designed to remedy the poor performance of TCP in fast long-
distance networks.
5.4. Investigating a Range of Environments
CUBIC has been extensively studied by using both NS-2 simulation and
test-bed experiments covering a wide range of network environments.
More information can be found in [HKLRX06].
Same as Standard TCP, CUBIC is a loss-based congestion control
algorithm. Therefore, CUBIC, which is designed to be more aggressive
than Standard TCP in fast and long distance networks, can fill large
drop-tail buffers more quickly than Standard TCP. In this case,
proper queue sizing and management [RFC7567] could be used to reduce
the packet queueing delay.
5.5. Protection against Congestion Collapse
With regard to the potential of causing congestion collapse, CUBIC
behaves like standard TCP since CUBIC modifies only the window
adjustment algorithm of TCP. Thus, it does not modify the ACK
clocking and Timeout behaviors of Standard TCP.
5.6. Fairness within the Alternative Congestion Control Algorithm.
CUBIC ensures convergence of competing CUBIC flows with the same RTT
in the same bottleneck links to an equal bandwidth share. When
competing flows have different RTTs, their bandwidth shares are
linearly proportional to the inverse of their RTT ratios. This is
true independent of the level of statistical multiplexing in the
link.
5.7. Performance with Misbehaving Nodes and Outside Attackers
This is not considered in the current CUBIC.
5.8. Behavior for Application-Limited Flows
CUBIC does not raise its congestion window size if the flow is
currently limited by the application instead of the congestion
window. In cases of idle periods, t in Eq. 1 MUST NOT include the
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idle time; otherwise, W_cubic(t) might be very high after restarting
from a long idle time.
5.9. Responses to Sudden or Transient Events
In case that there is a sudden congestion, a routing change, or a
mobility event, CUBIC behaves the same as Standard TCP.
5.10. Incremental Deployment
CUBIC requires only the change of TCP senders, and does not require
any assistant of routers.
6. Security Considerations
This proposal makes no changes to the underlying security of TCP.
7. IANA Considerations
There are no IANA considerations regarding this document.
8. Acknowledgements
Alexander Zimmermann and Lars Eggert have 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.
9. References
9.1. Normative References
[RFC2018] Mathis, M., Mahdavi, J., Floyd, S., and A. Romanow, "TCP
Selective Acknowledgment Options", RFC 2018,
DOI 10.17487/RFC2018, October 1996,
<http://www.rfc-editor.org/info/rfc2018>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC3649] Floyd, S., "HighSpeed TCP for Large Congestion Windows",
RFC 3649, DOI 10.17487/RFC3649, December 2003,
<http://www.rfc-editor.org/info/rfc3649>.
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[RFC4960] Stewart, R., Ed., "Stream Control Transmission Protocol",
RFC 4960, DOI 10.17487/RFC4960, September 2007,
<http://www.rfc-editor.org/info/rfc4960>.
[RFC5033] Floyd, S. and M. Allman, "Specifying New Congestion
Control Algorithms", BCP 133, RFC 5033,
DOI 10.17487/RFC5033, August 2007,
<http://www.rfc-editor.org/info/rfc5033>.
[RFC5348] Floyd, S., Handley, M., Padhye, J., and J. Widmer, "TCP
Friendly Rate Control (TFRC): Protocol Specification",
RFC 5348, DOI 10.17487/RFC5348, September 2008,
<http://www.rfc-editor.org/info/rfc5348>.
[RFC5681] Allman, M., Paxson, V., and E. Blanton, "TCP Congestion
Control", RFC 5681, DOI 10.17487/RFC5681, September 2009,
<http://www.rfc-editor.org/info/rfc5681>.
[RFC6582] Henderson, T., Floyd, S., Gurtov, A., and Y. Nishida, "The
NewReno Modification to TCP's Fast Recovery Algorithm",
RFC 6582, DOI 10.17487/RFC6582, April 2012,
<http://www.rfc-editor.org/info/rfc6582>.
[RFC7567] Baker, F., Ed. and G. Fairhurst, Ed., "IETF
Recommendations Regarding Active Queue Management",
BCP 197, RFC 7567, DOI 10.17487/RFC7567, July 2015,
<http://www.rfc-editor.org/info/rfc7567>.
9.2. Informative References
[CEHRX07] Cai, H., Eun, D., Ha, S., Rhee, I., and L. Xu, "Stochastic
Ordering for Internet Congestion Control and its
Applications", In Proceedings of IEEE INFOCOM , May 2007.
[FHP00] Floyd, S., Handley, M., and J. Padhye, "A Comparison of
Equation-Based and AIMD Congestion Control", May 2000.
[GV02] Gorinsky, S. and H. Vin, "Extended Analysis of Binary
Adjustment Algorithms", Technical Report TR2002-29,
Department of Computer Sciences , The University of Texas
at Austin , August 2002.
[HKLRX06] Ha, S., Kim, Y., Le, L., Rhee, I., and L. Xu, "A Step
toward Realistic Performance Evaluation of High-Speed TCP
Variants", International Workshop on Protocols for Fast
Long-Distance Networks , February 2006.
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[HRX08] Ha, S., Rhee, I., and L. Xu, "CUBIC: A New TCP-Friendly
High-Speed TCP Variant", ACM SIGOPS Operating System
Review , 2008.
[K03] Kelly, T., "Scalable TCP: Improving Performance in
HighSpeed Wide Area Networks", ACM SIGCOMM Computer
Communication Review , April 2003.
[LS08] Leith, D. and R. Shorten, "H-TCP: TCP Congestion Control
for High Bandwidth-Delay Product Paths", Internet-draft
draft-leith-tcp-htcp-06 , April 2008.
[XHR04] Xu, L., Harfoush, K., and I. Rhee, "Binary Increase
Congestion Control for Fast, Long Distance Networks", In
Proceedings of IEEE INFOCOM , March 2004.
Authors' Addresses
Injong Rhee
North Carolina State University
Department of Computer Science
Raleigh, NC 27695-7534
US
Email: rhee@ncsu.edu
Lisong Xu
University of Nebraska-Lincoln
Department of Computer Science and Engineering
Lincoln, NE 68588-0115
US
Email: xu@unl.edu
Sangtae Ha
University of Colorado at Boulder
Department of Computer Science
Boulder, CO 80309-0430
US
Email: sangtae.ha@colorado.edu
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Alexander Zimmermann
Phone: +49 175 5766838
Email: alexander.zimmermann@rwth-aachen.de
Lars Eggert
NetApp
Sonnenallee 1
Kirchheim 85551
Germany
Phone: +49 151 12055791
Email: lars@netapp.com
Richard Scheffenegger
Email: rscheff@gmx.at
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