RE: Packet Loss Signaling for Encrypted Protocols - draft-ferrieuxhamchaoui-tsvwg-lossbits

["Lubashev, Igor" <[e-mail]>]

From: Mikkel Fahnøe Jørgensen <[e-mail]>


The Q Period needs to be chosen carefully, since the observation could become too unreliable in case of packet reordering and loss if Q Period is too small. However, when Q Period is too large, short connections may not yield a useful upstream loss measurement.

Wrt. short connections, do you mean low-latency, small RTT, or short-lived?

By “short” I mean too few packets sent (fewer than half Q Period).  I will clarify this in the text. Thank you.

While this looks interesting, can you explain how the objectives compete or differ from the spin bit, and quality and information provided?

Latency Spin Bit (aka “spin bit”) measures connection rtt.  The proposed mechanism measures packet loss.  So the two are complementary measurement signals.

  *   Igor



On 9 July 2019 at 06.45.42, Lubashev, Igor ([e-mail]<mailto:[e-mail]>) wrote:
Alexandre, Isabelle, and I have posted a draft on a method for endpoints to signal packet loss to the path, while maintaining end user privacy and resisting ossification. The method is protocol-independent, but of course you get the most benefit by applying the method to encrypted transports, and QUIC is what people usually think of first in such context.

The draft is not targeted at the QUIC WG specifically, since it is describing a general method of such loss reporting. But we do mention QUIC, so the WG may find it interesting. We would welcome feedback from the QUIC WG.

Lars, Mark, I am sure the meeting agenda for Montreal is pretty tight, but if the WG is interested, we are happy to have a quick QUIC-specific presentation on this.

Thank you!

- Igor

P.S. We've implemented this proposal in some Akamai servers and have been using it to serve actual end-user QUIC traffic for a subset of Orange customers. Orange implemented a passive observer that used this signal to detect and identify loss. We can share the high-level of the results and will share the detailed analysis of the data and measurement techniques in maprg.

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https://datatracker.ietf.org/doc/draft-ferrieuxhamchaoui-tsvwg-lossbits/<https://urldefense.proofpoint.com/v2/url?u=https-3A__datatracker.ietf.org_doc_draft-2Dferrieuxhamchaoui-2Dtsvwg-2Dlossbits_&d=DwMFaQ&c=96ZbZZcaMF4w0F4jpN6LZg&r=Djn3bQ5uNJDPM_2skfL3rW1tzcIxyjUZdn_m55KPmlo&m=8tqj3OKmcGwAeTvifbhpZNwiGgQQrld_04cGqddUgas&s=GDUFlTwCpg_Ewg6sZuR0uKLJ5gLiW8qRPrb88Eoscr0&e=>

Abstract:
This document describes a protocol-independent method that employs
two bits to allow endpoints to signal packet loss in a way that can
be used by network devices to measure and locate the source of the
loss. The signaling method applies to all protocols with a protocol-
specific way to identify packet loss. The method is especially
valuable when applied to protocols that encrypt transport header and
do not allow an alternative method for loss detection.