RFC 9331 on The Explicit Congestion Notification (ECN) Protocol for Low Latency, Low Loss, and Scalable Throughput (L4S)

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        RFC 9331

        Title:      The Explicit Congestion Notification (ECN) 
                    Protocol for Low Latency, Low Loss, 
                    and Scalable Throughput (L4S) 
        Author:     K. De Schepper,
                    B. Briscoe, Ed.
        Status:     Experimental
        Stream:     IETF
        Date:       January 2023
        Mailbox:    koen.de_schepper@nokia.com,
                    ietf@bobbriscoe.net
        Pages:      52
        Updates/Obsoletes/SeeAlso:   None

        I-D Tag:    draft-ietf-tsvwg-ecn-l4s-id-29.txt

        URL:        https://www.rfc-editor.org/info/rfc9331

        DOI:        10.17487/RFC9331

This specification defines the protocol to be used for a new network
service called Low Latency, Low Loss, and Scalable throughput (L4S).
L4S uses an Explicit Congestion Notification (ECN) scheme at the IP
layer that is similar to the original (or 'Classic') ECN approach,
except as specified within. L4S uses 'Scalable' congestion control,
which induces much more frequent control signals from the network,
and it responds to them with much more fine-grained adjustments so
that very low (typically sub-millisecond on average) and consistently
low queuing delay becomes possible for L4S traffic without
compromising link utilization. Thus, even capacity-seeking (TCP-like)
traffic can have high bandwidth and very low delay at the same time,
even during periods of high traffic load.

The L4S identifier defined in this document distinguishes L4S from
'Classic' (e.g., TCP-Reno-friendly) traffic. Then, network
bottlenecks can be incrementally modified to distinguish and isolate
existing traffic that still follows the Classic behaviour, to prevent
it from degrading the low queuing delay and low loss of L4S traffic.
This Experimental specification defines the rules that L4S transports
and network elements need to follow, with the intention that L4S
flows neither harm each other's performance nor that of Classic
traffic. It also suggests open questions to be investigated during
experimentation. Examples of new Active Queue Management (AQM)
marking algorithms and new transports (whether TCP-like or real time)
are specified separately.

This document is a product of the Transport Area Working Group Working Group of the IETF.

EXPERIMENTAL: This memo defines an Experimental Protocol for the
Internet community.  It does not specify an Internet standard of any
kind. Discussion and suggestions for improvement are requested.
Distribution of this memo is unlimited.

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