Gap Analysis of Online Data Express Service (ODES)
draft-zhao-tsvwg-odes-gap-analysis-00

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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   This Internet-Draft will expire on 2 September 2024.

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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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