Internet DRAFT - draft-zhao-tsvwg-odes-gap-analysis
draft-zhao-tsvwg-odes-gap-analysis
tsvwg G. Zhao
Internet-Draft H. Yang
Intended status: Informational Z. Du
Expires: 2 September 2024 China Mobile
1 March 2024
Gap Analysis of Online Data Express Service (ODES)
draft-zhao-tsvwg-odes-gap-analysis-00
Abstract
This document is a gap analysis of online data express delivery
services, which is helpful to the design and development of online
data express delivery services.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Use Cases of ODES . . . . . . . . . . . . . . . . . . . . . . 2
3. Gap Analysis of ODES . . . . . . . . . . . . . . . . . . . . 3
3.1. TCP-based data transmission . . . . . . . . . . . . . . . 3
3.2. UDP-based data transmission . . . . . . . . . . . . . . . 3
3.3. RDMA-based data transmission . . . . . . . . . . . . . . 4
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
7.1. Normative References . . . . . . . . . . . . . . . . . . 5
7.2. Informative References . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
With the rapid development of diverse computing capabilities such as
general, intelligent, and super computing, the volume and complexity
of data processing have exploded, particularly in scenarios like
cloud disaster recovery, astronomical calculations, gene sequencing,
autonomous driving, and film and television production. Current
cloud service providers like AWS, Azure, and Alibaba Cloud have
introduced data migration solutions like Snowball, Data Box, and
Datatransport, respectively. However, most of these large-scale data
transfers still rely on offline hard drive delivery, which is
cumbersome, time-consuming, and has high security risks.
Assuming an end-to-end long-distance 100Gbps network link that can
ensure high bandwidth utilization, it can transmit about 1PB of data
in one day, which can meet most of the online transmission needs for
massive amounts of data. Compared to offline data migration, it has
advantages such as efficiency and security. Online data delivery can
change the way of offline transportation for data migration,
accelerate data circulation, liberate the geographical restrictions
of computing, empower various industries, and drive the development
of the digital economy and society.
2. Use Cases of ODES
Please refer to the document of Use Cases and Problem Statement of
Data Express Service.
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3. Gap Analysis of ODES
The speed of data transmission depends on both the transmission
bandwidth on the network side and the performance of the protocol
stack on the end side. Currently, the bandwidth of the core network
can generally reach more than 10Gbps, and some networks can support
bandwidths of more than 100Gbps. However, the end-to-end single-
stream data transmission bandwidth on the wide area network is
generally less than 1Gbps (most mainstream transmission protocols use
TCP, and the performance is generally within 50Mbps). Existing
technologies such as multi-stream concurrency and network offloading
also struggle to achieve high-throughput (100Gbps or higher) data
transmission."
3.1. TCP-based data transmission
Traditional TCP network congestion control and packet loss
retransmission techniques are difficult to meet the performance
requirements of high-throughput network transmission in wide area
networks. In recent years, many new high-throughput versions of TCP
protocols and TCP acceleration devices have emerged. These improved
TCP protocols mainly focus on dynamically adjusting the congestion
window size and increasing congestion detection signals. However,
they do not fundamentally address the limitations of the AIMD
mechanism in terms of high throughput. In wide area networks, packet
loss due to physical media errors or sudden traffic spikes is
unavoidable and cannot be ignored. As packet loss and delay
increase, the end-to-end throughput of these improved TCP protocols
decreases significantly. In a network environment with 0.1% packet
loss and an RTT of 10ms, the single-stream throughput rate is below
50Mbps [FASP].
3.2. UDP-based data transmission
TCP's reliable mechanism can reduce network throughput and increase
average latency. Due to the complexity of modifying TCP itself, in
recent years, both academic and industry circles have designed new
transmission schemes based on the UDP protocol, using UDP as an
alternative to TCP to achieve reliability at the application layer,
such as UDT, QUIC, and other schemes.
Most of these data transmission schemes based on UDP retransmit lost
packets through some method, but they do not consider the risks of
available bandwidth and network collapse, and there is also a
phenomenon of seizing TCP traffic. UDT uses UDP to reliably move
data, with a more aggressive data transmission mechanism and a
dynamic AIMD congestion avoidance algorithm, and implements packet
loss retransmission through the NACK mechanism. This method
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outperforms TCP in certain scenarios with optimized parameters, but
in typical wide area networks, UDT's transmission performance is
lower than TCP. UDT's aggressive data transmission mechanism can
also easily lead to rate oscillation and packet loss, which not only
destroys its own throughput but also affects other traffic in the
network.
QUIC, based on UDP, has designed a new protocol stack optimized for
the interactive application characteristics of http3.0, with
improvements in connection establishment, connection migration,
multi-stream multiplexing, congestion control, and forward error
correction. However, in long-fat pipeline and complex network
environments, QUIC cannot compete with TCP in terms of sustained
throughput performance [QUIC(k)].
Aspera FASP is also a new transmission protocol designed based on
UDP. It completely separates reliability and rate control from data
transmission, quickly adjusts the sending rate by periodically
probing the queuing delay in the network, and designs an application-
layer packet loss retransmission mechanism to ensure reliability and
high bandwidth utilization. However, FASP cannot be used in
applications where byte streams are transmitted in order, and network
throughput is also limited by disk IO, file systems, CPU scheduling,
etc.
3.3. RDMA-based data transmission
RDMA utilizes technologies such as zero-copy memory, kernel bypass,
and CPU offloading to offload the entire TCP/IP protocol stack to the
network card, allowing user-space applications to directly read and
write to remote host memory. This avoids data copying and context
switching, achieving high throughput, low latency, and low CPU power
consumption. There are three technical paths for RDMA technology:
Infinite Bandwidth Technology InfiniBand, RDMA over Converged
Ethernet (RoCE) based on converged Ethernet, and Internet Wide Area
RDMA Protocol (iWARP). Among them, RoCE technology has two versions:
RoCEv1 and RoCEv2. RoCEv2 is widely used in data center networks due
to its compatibility with traditional TCP/IP and ease of deployment
and management, mainly in high-performance storage, high-performance
computing, and other scenarios.
Although RDMA has very high transmission performance, with some
manufacturers achieving speeds of 400Gbps, current RDMA technology
generally requires operation on lossless networks and cannot be used
in general wide-area networks. When the packet loss rate exceeds
0.01%, the throughput of RDMA will drop significantly, which is the
root cause of why existing RDMA cannot operate in wide-area networks.
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4. IANA Considerations
TBD.
5. Security Considerations
TBD.
6. Acknowledgements
TBD.
7. References
7.1. 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>.
7.2. Informative References
[FASP] "IBM Aspera FASP High-Speed transport", IBM-Cloud White
paper.
[QUICk] Konig, M., Waldhorst, O., and M. Zitterbart, "QUIC(k)
Enough in the Long Run? Sustained Throughput Performance
of QUIC Implementations", IEEE 48th Conference on Local
Computer Networks (LCN) 979-8-3503-0073-4 23, DOI 10.1109
LCN58197.2023.10223395, October 2023,
<https://doi.org/10.1109 LCN58197.2023.10223395>.
Authors' Addresses
Guangyu Zhao
China Mobile
No.32 XuanWuMen West Street
Beijing
100053
China
Email: zhaoguangyu@chinamobile.com
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Hongwei Yang
China Mobile
No.32 XuanWuMen West Street
Beijing
100053
China
Email: yanghongwei@chinamobile.com
Zongpeng Du
China Mobile
No.32 XuanWuMen West Street
Beijing
100053
China
Email: duzongpeng@foxmail.com
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