Quic Timestamps For Measuring One-Way Delays
draft-huitema-quic-ts-03
Network Working Group C. Huitema
Internet-Draft Private Octopus Inc.
Intended status: Experimental August 10, 2020
Expires: February 11, 2021
Quic Timestamps For Measuring One-Way Delays
draft-huitema-quic-ts-03
Abstract
The TIME_STAMP frame can be added to Quic packets when one way delay
measurements is useful. The timestamp is set to the number of
microseconds from the beginning of the connection to the time at
which the packet is sent. The draft defines the "enable_time_stamp"
transport parameter for negotiating the use of this extension frame,
and a new frame types for the time_stamped frame.
Status of This Memo
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Internet-Draft QUIC-TS August 2020
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Table of Contents
1. Measuring One-Way Delays . . . . . . . . . . . . . . . . . . 2
1.1. Terms and Definitions . . . . . . . . . . . . . . . . . . 3
2. Specification . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Negotiation . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Sending TIME_STAMP frames . . . . . . . . . . . . . . . . 4
2.3. TIME_STAMP frame format . . . . . . . . . . . . . . . . . 4
2.4. RTT Measurements . . . . . . . . . . . . . . . . . . . . 5
2.5. One-Way Delay Measurements . . . . . . . . . . . . . . . 5
3. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1. Management of Time . . . . . . . . . . . . . . . . . . . 6
4. Security Considerations . . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Normative References . . . . . . . . . . . . . . . . . . 8
7.2. Informative References . . . . . . . . . . . . . . . . . 9
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 9
1. Measuring One-Way Delays
The QUIC Transport Protocol [I-D.ietf-quic-transport] provides a
secure, multiplexed connection for transmitting reliable streams of
application data. The algorithms for QUIC Loss Detection and
Congestion Control [I-D.ietf-quic-recovery] use measurement of Round
Trip Time (RTT) to determine when packets should be retransmitted.
RTT measurements are useful, but there are however many cases in
which more precise One-Way Delay (1WD) measurements enable more
efficient Loss Detection and Congestion Control.
An example would be the Low Extra Delay Background Transport (LEDBAT)
[RFC6817] which uses variations in transmission delay to detect
competition for transmission resource. Experience shows that while
LEDBAT may be implemented using RTT measurements, it is somewhat
inefficient because it will cause unnecessary slowdowns in case of
queues or delayed ACKs on the return path. Using 1WD solves these
issues. Similar argument can be made for most delay-based
algorithms.
We propose to enable one way delay measurements in QUIC by defining a
TIME_STAMP frame carrying the time at which a packet is sent. The
use of this extension frame is negotiated with a transport parameter,
"enable_time_stamp". When the extension is negotiated by both
Huitema Expires February 11, 2021 [Page 2]
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