Network Working Group H. Liu
Internet-Draft R. Miao
Intended status: Experimental Alibaba Group
Expires: December 19, 2020 R. Pan
JK. Lee
C. Kim
Intel Corporation
June 17, 2020
HPCC++: Enhanced High Precision Congestion Control
draft-pan-tsvwg-hpccplus-00
Abstract
Congestion control (CC) is the key to achieving ultra-low latency,
high bandwidth and network stability in high-speed networks.
However, the existing high-speed CC schemes have inherent limitations
for reaching these goals.
In this document, we describe HPCC++ (High Precision Congestion
Control), a new high-speed CC mechanism which achieves the three
goals simultaneously. HPCC++ leverages in-network telemetry (INT) to
obtain precise link load information and controls traffic precisely.
By addressing challenges such as delayed INT information during
congestion and overreaction to INT information, HPCC++ can quickly
converge to utilize free bandwidth while avoiding congestion, and can
maintain near-zero in-network queues for ultra-low latency. HPCC++
is also fair and easy to deploy in hardware, implementable with
commodity programmable NICs and switches.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents 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 December 19, 2020.
Liu, et al. Expires December 19, 2020 [Page 1]
Internet-Draft HPCC++ June 2020
Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
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
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. System Overview . . . . . . . . . . . . . . . . . . . . . . . 4
4. HPCC++ Algorithm . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Notations . . . . . . . . . . . . . . . . . . . . . . . . 5
4.2. Design Functions and Procedures . . . . . . . . . . . . . 6
5. Configuration Parameters . . . . . . . . . . . . . . . . . . 7
6. Design Enhancement and Implementation . . . . . . . . . . . . 8
6.1. HPCC++ Guidelines . . . . . . . . . . . . . . . . . . . . 8
6.2. Receiver-based HPCC . . . . . . . . . . . . . . . . . . . 9
6.3. Switch-side Optimizations . . . . . . . . . . . . . . . . 10
7. Reference Implementations . . . . . . . . . . . . . . . . . . 10
7.1. INT padding at switches . . . . . . . . . . . . . . . . . 11
7.2. Congestion control at NICs . . . . . . . . . . . . . . . 11
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
9. Security Considerations . . . . . . . . . . . . . . . . . . . 12
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13
11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 13
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
12.1. Normative References . . . . . . . . . . . . . . . . . . 13
12.2. Informative References . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
1. Introduction
The link speed in data center networks has grown from 1Gbps to
100Gbps in the past decade, and this growth is continuing. Ultralow
latency and high bandwidth, which are demanded by more and more
applications, are two critical requirements in today's and future
high-speed networks.
Liu, et al. Expires December 19, 2020 [Page 2]
Internet-Draft HPCC++ June 2020
Given that traditional software-based network stacks in hosts can no
longer sustain the critical latency and bandwidth requirements
[Zhu-SIGCOMM2015], offloading network stacks into hardware is an
inevitable direction in high-speed networks. large-scale networks
with RDMA (remote direct memory access) over Converged Ethernet
Version 2 (RoCEv2) often becomes hardware-offloading solution.
Unfortunately, the RDMA networks still face fundamental challenges to
reconcile low latency, high bandwidth utilization, and high
stability.
This document describes a new CC mechanism, HPCC++ (Enhanced High
Precision Congestion Control), for large-scale, high-speed networks.
The key idea behind HPCC++ is to leverage the precise link load
information from INT to compute accurate flow rate updates. Unlike
existing approaches that often require a large number of iterations
to find the proper flow rates, HPCC++ requires only one rate update
step in most cases. Using precise information from INT enables
HPCC++ to address the three limitations in current CC schemes.
First, HPCC++ senders can quickly ramp up flow rates for high
utilization or ramp down flow rates for congestion avoidance.
Second, HPCC++ senders can quickly adjust the flow rates to keep each
link's input rate slightly lower than the link's capacity, preventing
queues from being built-up as well as preserving high link
utilization. Finally, since sending rates are computed precisely
based on direct measurements at switches, HPCC++ requires merely
three independent parameters that are used to tune fairness and
efficiency.
The base form of HPCC++ is the original HPCC algorithm and its full
description can be found in [SIGCOMM-HPCC]. While the original
design lays the foundation for INT-based precision congestion
control, HPCC++ is an enhanced version which takes into account
system constraints and aims to reduce the design overhead and further
improves the performance. Section 6 describes these detailed
proposed design enhancements and guidelines.
2. Terminology
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 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
Liu, et al. Expires December 19, 2020 [Page 3]
Internet-Draft HPCC++ June 2020
3. System Overview
Figure 1 shows the end-to-end system that HPCC++ operates in. During
the propagation of the packet from the sender to the receiver, each
switch along the path leverages the INT feature of its switching ASIC
to insert some meta-data that reports the current load of the
packet's egress port, including timestamp (ts), queue length (qLen),
transmitted bytes (txBytes), and the link bandwidth capacity (B).
When the receiver gets the packet, it can copies all the meta-data
recorded by the switches to the ACK message it sends back to the
sender, and then the sender decides how to adjust its flow rate each
time it receives an ACK with network load information.
Alternatively, the receiver can calculate the flow rate based on the
INT information and feedback the calculated rate back to the sender.
The nofication packets would include delayed ack information as well.
Note that there also exist network nodes along the reverse
(potentially uncongested) path that the RTCP feedback reports
traverse. Those network nodes are not shown in the figure for sake
of brevity.
+---------+ pkt +-------+ pkt+int +-------+ pkt+int +----------+
| Data |------>| |-------->| |-------->| Data |
| Sender |=======|Switch1|=========|Switch2|=========| Receiver |
+---------+ +-------+ Link-1 +-------+ Link-2 +----------+
/|\ |
| |
+-------------------------------------------------------+
Notification Packets/ACKs
Figure 1: System Overview
o Data sender: responsible for controlling inflight bytes. HPCC++
is a window-based CC scheme that controls the number of inflight
bytes. The inflight bytes mean the amount of data that have been
sent, but not acknowledged at the sender yet. Controlling
inflight bytes has an important advantage compared to controlling
rates. In the absence of congestion, the inflight bytes and rate
are interchangeable with equation inflight = rate * T where T is
the base propagation RTT. The rate can be calculated locally or
obtained from the notification packet.
o Network nodes: responsible of inserting the INT information to the
data packet. The INT information reports the current load of the
packet's egress port, including timestamp (ts), queue length
(qLen), transmitted bytes (txBytes), and the link bandwidth
Liu, et al. Expires December 19, 2020 [Page 4]
Internet-Draft HPCC++ June 2020
capacity (B). Note that the INT information can be nested with
each network node adds its own information or more capable network
nodes may compare its INT information against the one in the
packet header. If its congestion is more severe, the node may
replace the packet's INT information with its own.
o Data receiver: responsible for either reflecting back the INT
information in the data packet using ACKs or calculating the
proper flow rate based on network congestion information in INT
and sending notification packets back to the sender.
4. HPCC++ Algorithm
HPCC++ is a window-based congestion control algorithm. The key
design choice of HPCC++ is to rely on network nodes to provide fine-
grained load information, such as queue size and accumulated tx/rx
traffic to compute precise flow rates. This has two major benefits:
(i) HPCC++ can quickly converge to proper flow rates to highly
utilize bandwidth while avoiding congestion; and (ii) HPCC++ can
consistently maintain a close-to-zero queue for low latency.
This section introduces the list of notations and describes the core
congestion control algorithm.
4.1. Notations
This section summarizes the list of variables and parameters used in
the HPCC++ algorithm. Figure 3 also includes the default values for
choosing the algorithm parameters either to represent a typical
setting in practical applications or based on theoretical and
simulation studies.
+--------------+-------------------------------------------------+
| Notation | Variable Name |
+--------------+-------------------------------------------------+
| W_i | Window for flow i |
| Wc_i | Reference window for flow i |
| B_j | Bandwidth for Link j |
| I_j | Estimated inflight bytes for Link j |
| U_j | Normalized inflight bytes for Link j |
| qlen | INT information: link j queue length |
| txRate | INT information: link j output rate |
| ts | INT information: timestamp |
| txBytes | INT information: link j total transmitted bytes |
| | associated with timestamp ts |
+--------------+-------------------------------------------------+
Figure 2: List of variables.
Liu, et al. Expires December 19, 2020 [Page 5]
Internet-Draft HPCC++ June 2020
+--------------+----------------------------------+----------------+
| Notation | Parameter Name | Default Value |
+--------------+----------------------------------+----------------+
| T | Known baseline RTT | 5us |
| eta | Target link utilization | 95% |
| maxStage | Maximum stages for additive | |
| | increases | 5 |
| N | Maximum number of flows | ... |
| W_ai | Additive increase amount | ... |
+--------------+----------------------------------+----------------+
Figure 3: List of algorithm parameters and their default values.
4.2. Design Functions and Procedures
The HPCC++ algorithm can be outlined as below:
1: Function MeasureInflight(ack)
2: u = 0;
3: for each link i on the path do
4: ack.L[i].txBytes-L[i].txBytes
txRate = ----------------------------- ;
ack.L[i].ts-L[i].ts
5: min(ack.L[i].qlen,L[i].qlen) txRate
u' = ----------------------------- + ---------- ;
ack.L[i].B*T ack.L[i].B
6: if u' > u then
7: u = u'; tau = ack.L[i].ts - L[i].ts;
8: tau = min(tau, T);
9: U = (1 - tau/T)*U + tau/T*u;
10: return U;
11: Function ComputeWind(U, updateWc)
12: if U >= eta or incStage >= maxStagee then
13: Wc
W = ----- + W_ai;
U/eta
14: if updateWc then
15: incStagee = 0; Wc = W ;
16: else
17: W = Wc + W_ai ;
18: if updateWc then
19: incStage++; Wc = W ;
20: return W
Liu, et al. Expires December 19, 2020 [Page 6]
Internet-Draft HPCC++ June 2020
21: Procedure NewAck(ack)
22: if ack.seq > lastUpdateSeq then
23: W = ComputeWind(MeasureInflight(ack), True);
24: lastUpdateSeq = snd_nxt;
25: else
26: W = ComputeWind(MeasureInflight(ack), False);
27: R = W/T; L = ack.L;
The above illustrates the overall process of CC at the sender side
for a single flow. Each newly received ACK message triggers the
procedure NewACK at Line 21. At Line 22, the variable lastUpdateSeq
is used to remember the first packet sent with a new W c , and the
sequence number in the incoming ACK should be larger than
lastUpdateSeq to trigger a new sync betweenW c andW (Line 14-15 and
18-19). The sender also remembers the pacing rate and current INT
information at Line 27. The sender computes a new window size W at
Line 23 or Line 26, depending on whether to update W c , with
function MeasureInflight and ComputeWind. Function MeasureInflight
estimates normalized inflight bytes with Eqn (2) at Line 5. First,
it computes txRate of each link from the current and last accumulated
transferred bytes txBytes and timestamp ts (Line 4). It also uses
the minimum of the current and last qlen to filter out noises in qlen
(Line 5). The loop from Line 3 to 7 selects maxi(Ui) in Eqn. (3).
Instead of directly using maxi(Ui), we use an EWMA (Exponentially
Weighted Moving Average) to filter the noises from timer inaccuracy
and transient queues. (Line 9). Function ComputeWind combines
multiplicative increase/ decrease (MI/MD) and additive increase (AI)
to balance the reaction speed and fairness. If a sender finds it
should increase the window size, it first tries AI for maxStage times
with the stepWAI (Line 17). If it still finds room to increase after
maxStage times of AI or the normalized inflight bytes is above, it
calls Eqn (4) once to quickly ramp up or ramp down the window size
(Line 12-13).
5. Configuration Parameters
HPCC++ has three easy-to-set parameters: eta, maxStagee, and W_ai.
eta controls a simple tradeoff between utilization and transient
queue length (due to the temporary collision of packets caused by
their random arrivals, so we set it to 95% by default, which only
loses 5% bandwidth but achieves almost zero queue. maxStage controls
a simple tradeoff between steady state stability and the speed to
reclaim free bandwidth. We find maxStage = 5 is conservatively large
for stability, while the speed of reclaiming free bandwidth is still
much faster than traditional additive increase, especially in high
bandwidth networks. W_ai controls the tradeoff between the maximum
number of concurrent flows on a link that can sustain near-zero
Liu, et al. Expires December 19, 2020 [Page 7]
Internet-Draft HPCC++ June 2020
queues and the speed of convergence to fairness. Note that none of
the three parameters are reliability-critical.
HPCC++'s design intentionally brings advantages to short-lived flows,
by allowing flows starting at line-rate and the separation of
utilization convergence and fairness convergence. HPCC++ achieves
fast utilization convergence to mitigate congestion in almost one
round-trip time, while allows flows to gradually converge to
fairness. This design choice is especially helpful for the workload
of datacenter applications, where the majority of flows are short and
latency-sensitive. Normally we set a very small W_ai to support a
large number of concurrent flows on a link, because slower fairness
is not critical. A rule of thumb is to set W_ai = W_init*(1-eta) / N
where N is the expected or receiver reported maximum number of
concurrent flows on a link. The intuition is that the total additive
increase every round (N*W_ai ) should not exceed the bandwidth
headroom, and thus no queue forms. Even if the actual number of
concurrent flows on a link exceeds N, the CC is still stable and
achieves full utilization, but just cannot maintain zero queues.
6. Design Enhancement and Implementation
The basic design of HPCC++, i.e. HPCC, as described above is to add
INT information into every date packet to response congestion as soon
as the very first packet observing the network congestion. This is
especially helpful to reduce the risk of severe congestion in incast
scenario at the first round-trip time. In addition, original HPCC's
algorithm of introducing Wc is for the purpose of solving the over-
reaction issue from using this per-packet response.
Alternatively, the INT information needs not to be added to every
data packet to reduce the overhead. Switches can generate INT less
frequently, e.g., once per RTT or upon congestion happening.
6.1. HPCC++ Guidelines
To ensure network stability, HPCC++ establishes a few guidelines for
different implementations:
o The algorithm should commit the window/rate update at most once
per round-trip time, similar to the procedure of updating Wc.
o To support different workloads and to properly set W_ai, HPCC++
allows the option to incorporate mechanisms to speed up the
fairness convergence.
o The switch should capture INT information that includes link load
(txBytes, ts, qlen) and link spec (switch ID, egress port ID, port
Liu, et al. Expires December 19, 2020 [Page 8]
Internet-Draft HPCC++ June 2020
speed) at the egress port. Note, each switch should record all
those information at the single snapshot to achieve a precise link
load estimate.
o HPCC++ can optionally use a probe packet to query the INT
information. Thereby, the probe packets should take the same
routing path and QoS queueing with the data packets.
As long the above guidelines are met, this document does not mandate
a particular INT header format or encapsulation, which are orthogonal
to the HPCC++ algorithms described in this document. The algorithm
can be implemented with a choice of in-band network telemetry
[P4-INT], [I-D.ietf-ippm-ioam-data], [I-D.ietf-kumar-ippm-ifa].
6.2. Receiver-based HPCC
Note that the window/rate calculation can be implemented at either
the data sender or the data receiver. If the ACK packets already
exist for reliability purpose, the INT information can be echoed back
to the sender via ACK self-clocking. Not all ACK packets need to
carry the INT information. To reduce the Packet Per Second (PPS)
overhead, the receiver may examine the INT information and adopt the
technique of delayed ACKs that only sends out an ACK for a few of
received packets. In order to reduce PPS even further, one may
implement the algorithm at the receiver and feedback the calculated
window in the ACK packet once every RTT.
The receiver-based algorithm, Rx-HPCC, is based on int.L, which is
the INT information in the packet header. The receiver performs the
same functions except using int.L instead of ack.L. The new function
NewINT(int.L) is to replace NewACK(int.L)
28: Procedure NewINT(int.L)
29: if now > (lastUpdateTime + T) then
30: W = ComputeWind(MeasureInflight(int), True);
31: send_ack(W)
32: lastUpdateTime = now;
33: else
34: W = ComputeWind(MeasureInflight(int), False);
Here, since the receiver does not know the starting sequence number
of a burst, it simply records the lastUpdateTime. If time T has
passed since lastUpdateTime, the algorithm would recalcuate Wc as in
Line 30 and send out the ACK packet which would include W informtion.
Otherwise, it would just update W information locally. This would
reduce the amount of traffic that needs to be feedback to the data
sender.
Liu, et al. Expires December 19, 2020 [Page 9]
Internet-Draft HPCC++ June 2020
Note that the receiver can also measure the number of outstanding
flows, N, if the last hop is the congestion point and use this
information to dynamically adjust W_ai to achieve better fairness.
The improvement would allow flows to quickly converge to fairness
without causing large swings under heavy load.
6.3. Switch-side Optimizations
Switches can potentially generate and send separate packets
containing INT information (aka INT response packets) directly back
to the data senders so that they can slow down as soon as possible.
This fast feedback and reaction can further reduce buffer size
consumption upon heavy incast. Switches can consider the level of
congestion to decide when to trigger direct INT responses. A simple
bloom-filter and timer can be used at switches to avoid sending a
burst of INT responses to the same sender. An INT response packet
must carry the sequence number of the original data packet, so that
the sender can correctly correlate the INT response with the data
packet triggered the INT response.
One may optimize the INT header overhead by implementing a simple
subscription-based INT. The data senders may simply use a different
DSCP codepoint or a flag bit in the INT instruction header to
indicate INT subscription. (We expect future INT specs to support
such a subscription service.) The senders can selectively subscribe
to INT on a per-packet basis to control the INT data overhead. While
forwarding INT-subscribed data packets, the switches can monitor the
level of congestion and conditionally generate separate INT responses
as described above. The INT responses can be directly sent back to
the senders or to the receivers depending on which version of HPCC++
algorithm (sender-based or receiver-based) is used in the network.
7. Reference Implementations
A prototype of HPCC++ in commodity NICs with FPGA programmability is
implemented to realize the CC algorithm and commodity switching ASICs
with P4 programmability to realize a standard INT feature.
Liu, et al. Expires December 19, 2020 [Page 10]
Internet-Draft HPCC++ June 2020
+----------------------------------------------+
| +-----------------------------------------+ |
| | PCIe Module |<-|-> Main Memory
| +-----------------------------------------+ |
| /|\ |
| | control, DMA |
| \|/ |
| +-----------------------------------------+ |
| | Congestion Control Module | |
| +-----------------------------------------+ |
| Update | /|\ Notify |
| \|/ | |
| +-----------------------------------------+ |
| | Flow Scheduler | |
| +-----------------------------------------+ |
| PktSend | /|\ Notify |
| \|/ | |
| +---------------+ PktRecv +---------------+ |
| | Tx Pipe |<--------| Rx Pipe | |
| +---------------+ +---------------+ |
| | /|\ |
| \|/ | |
| +-----------------------------------------+ |
| | MAC Module |<-|-> Ethernet Adapter
| +-----------------------------------------+ |
+----------------------------------------------+
Figure 4: Overview of NIC Implementation
7.1. INT padding at switches
HPCC++ only relies on packets to share information across senders,
receivers, and switches. HPCC++ is open to a variety of INT format
standards. Inside a data center, the path length is often no more
than 5 hops. The overhead of the INT padding for HPCC++ is low.
7.2. Congestion control at NICs
Figure 4 shows HPCC++ implementation on a commodity programmable NIC.
The NIC provides an FPGA chip which is connected to the main memory
with a vendor-provided PCIe module and the Ethernet adapter with a
vendor-provided MAC module. Sitting between the PCIe and MAC
modules, HPCC++ modules realize both sender and receiver roles.
The Congestion Control (CC) module implements the sender side CC
algorithm. It receives ACK events which are generated from the RX
pipeline, adjusts the sending window and rate, and stores the new
Liu, et al. Expires December 19, 2020 [Page 11]
Internet-Draft HPCC++ June 2020
sending window and rate for the flow of the current ACK in the flow
scheduler via an Update event.
The flow scheduler paces flow rates with a credit-based mechanism.
Specifically, it scans through all the flows in a round-robin manner
and assigns credit to each flow proportional to its current pacing
rate. It also maintains the current sending window size and
unacknowledged packets for active flows. If a flow has accumulated
sufficient credits to send one packet and the flow's sending window
permits, the flow scheduler invokes a PktSend event to TX pipe.
The TX pipe implements IB/UDP/IP stacks for running in RoCEv2. It
maintains the flow context for each of concurrent flows, including
5-tuples, the packet sequence number (PSN), destination QP (queue
pair), etc. Once it receives the PktSend event with QP ID from the
flow scheduler, it generates the corresponding packet and delivers to
the MAC module.
The RX pipe parses the incoming packets from the MAC module and
generates multiple events to other HPCC++ modules. (1) On receiving a
data packet, the RX pipe extracts its flow context and invokes a
PktRecv event to the TX pipe to formulate a corresponding ACK packet.
If the packet is out-of-sequence (OOS), the TX pipe sends a NAK
instead. (2) On receiving an ACK packet, the RX pipe extracts the
network status from the packet and passes it to the CC module via the
flow scheduler. (3) On receiving a NAK, the RX pipe notifies the TX
pipe to start go-back-to-N retransmission. (4) On receiving a control
packet with an RDMA operation, the RX pipe notifies the flow
scheduler to create a flow with a new QP ID, or remove an existing
flow. Currently, HPCC++ supports two operations: RDMA WRITE and RDMA
READ. We leave the full support of IB verbs as future work.
8. IANA Considerations
This document makes no request of IANA.
9. Security Considerations
The rate adaptation mechanism in HPCC++ relies on feedback from the
data receiver. As such, it is vulnerable to attacks where feedback
messages are hijacked, replaced, or intentionally injected with
misleading information resulting in denial of service, similar to
those that can affect TCP. It is therefore RECOMMENDED that the
notification feedback message is at least integrity checked. In
addition, [I-D.ietf-avtcore-cc-feedback-message] discusses the
potential risk of a receiver providing misleading congestion feedback
information and the mechanisms for mitigating such risks.
Liu, et al. Expires December 19, 2020 [Page 12]
Internet-Draft HPCC++ June 2020
10. Acknowledgments
The authors would like to thank ... for their valuable review
comments and helpful input to this specification.
11. Contributors
The following individuals have contributed to the implementation and
evaluation of the proposed scheme, and therefore have helped to
validate and substantially improve this specification: Pedro Y.
Segura, Roberto P. Cebrian, Robert Southworth and Malek Musleh.
12. References
12.1. 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>.
[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>.
12.2. Informative References
[I-D.ietf-avtcore-cc-feedback-message]
Sarker, Z., Perkins, C., Singh, V., and M. Ramalho, "RTP
Control Protocol (RTCP) Feedback for Congestion Control",
draft-ietf-avtcore-cc-feedback-message-06 (work in
progress), March 2020.
[I-D.ietf-ippm-ioam-data]
"Data Fields for In-situ OAM", March 2020,
<https://tools.ietf.org/html/draft-ietf-ippm-ioam-data-
09>.
[I-D.ietf-kumar-ippm-ifa]
"Inband Flow Analyzer", February 2019,
<https://tools.ietf.org/html/draft-kumar-ippm-ifa-01>.
[P4-INT] "In-band Network Telemetry (INT) Dataplane Specification,
v2.0", February 2020, <https://github.com/p4lang/p4-
applications/blob/master/docs/INT_v2_0.pdf>.
Liu, et al. Expires December 19, 2020 [Page 13]
Internet-Draft HPCC++ June 2020
[SIGCOMM-HPCC]
Li, Y., Miao, R., Liu, H., Zhuang, Y., Fei Feng, F., Tang,
L., Cao, Z., and M. Zhang, "HPCC: High Precision
Congestion Control", ACM SIGCOMM Beijing, China, August
2019.
[Zhu-SIGCOMM2015]
Zhu, Y., Eran, H., Firestone, D., Guo, C., Lipshteyn, M.,
Liron, Y., Padhye, J., Raindel, S., Yahia, M., and M.
Zhang, "Congestion Control for Large-Scale RDMA
Deployments", ACM SIGCOMM London, United Kingdom, August
2015.
Authors' Addresses
Hongqiang H. Liu
Alibaba Group
108th Ave NE, Suite 800
Bellevue, WA 98004
USA
Email: hongqiang.liu@alibaba-inc.com
Rui Miao
Alibaba Group
525 Almanor Ave, 4th Floor
Sunnyvale, CA 94085
USA
Email: miao.rui@alibaba-inc.com
Rong Pan
Intel, Corp.
2200 Mission College Blvd.
Santa Clara, CA 95054
USA
Email: rong.pan@intel.com
Liu, et al. Expires December 19, 2020 [Page 14]
Internet-Draft HPCC++ June 2020
Jeongkeun Lee
Intel, Corp.
4750 Patrick Henry Dr.
Santa Clara, CA 95054
USA
Email: jk.lee@intel.com
Changhoon Kim
Intel Corporation
4750 Patrick Henry Dr.
Santa Clara, CA 95054
USA
Email: chang.kim@intel.com
Liu, et al. Expires December 19, 2020 [Page 15]