rfc9331_term_short.txt   rfc9332_term_reordered.txt 
Classic Congestion Control: A congestion control behaviour that can Classic Congestion Control: A congestion control behaviour that can
coexist with standard Reno [RFC5681] without causing significantly coexist with standard Reno [RFC5681] without causing significantly
negative impact on its flow rate [RFC5033]. With Classic negative impact on its flow rate [RFC5033]. With Classic
congestion controls, such as Reno or CUBIC, because the flow rate congestion controls, such as Reno or CUBIC, because the flow rate
has scaled since TCP congestion control was first designed in has scaled since TCP congestion control was first designed in
1988, it now takes hundreds of round trips (and growing) to 1988, it now takes hundreds of round trips (and growing) to
recover after a congestion signal (whether a loss or an ECN mark) recover after a congestion signal (whether a loss or an ECN mark)
as shown in the examples in Section 5.1 of the L4S architecture as shown in the examples in Section 5.1 of the L4S architecture
[RFC9330] and in [RFC3649]. Therefore, control of queuing and [RFC9330] and in [RFC3649]. Therefore, control of queuing and
utilization becomes very slack, and the slightest disturbances utilization becomes very slack, and the slightest disturbances
(e.g., from new flows starting) prevent a high rate from being (e.g., from new flows starting) prevent a high rate from being
attained. attained.
Scalable Congestion Control: A congestion control where the average Scalable Congestion Control: A congestion control where the average
time from one congestion signal to the next (the recovery time) time from one congestion signal to the next (the recovery time)
remains invariant as the flow rate scales, all other factors being remains invariant as the flow rate scales, all other factors being
equal. This maintains the same degree of control over queuing and equal. This maintains the same degree of control over queuing and
utilization whatever the flow rate, as well as ensuring that high utilization whatever the flow rate, as well as ensuring that high
throughput is robust to disturbances. For instance, DCTCP throughput is robust to disturbances. For instance, DCTCP
averages 2 congestion signals per round trip, whatever the flow averages 2 congestion signals per round trip, whatever the flow
rate, as do other recently developed Scalable congestion controls, rate, as do other recently developed Scalable congestion controls,
e.g., Relentless TCP [RELENTLESS], TCP Prague [PRAGUE-CC] e.g., Relentless TCP [RELENTLESS], TCP Prague [PRAGUE-CC]
[PragueLinux], BBRv2 [BBRv2] [BBR-CC], and the L4S variant of [PragueLinux], BBRv2 [BBRv2] [BBR-CC], and the L4S variant of
SCReAM for real-time media [SCReAM] [RFC8298]. See Section 4.3 SCReAM for real-time media [SCReAM] [RFC8298]. For the public
for more explanation. Internet, a Scalable transport has to comply with the requirements
in Section 4 of [RFC9331] (aka the 'Prague L4S requirements').
Classic Service: The Classic service is intended for all the Classic Service: The Classic service is intended for all the
congestion control behaviours that coexist with Reno [RFC5681] congestion control behaviours that coexist with Reno [RFC5681]
(e.g., Reno itself, CUBIC [RFC8312], Compound [CTCP], and TFRC (e.g., Reno itself, CUBIC [RFC8312], and TFRC [RFC5348]). The
[RFC5348]). The term 'Classic queue' means a queue providing the term 'Classic queue' means a queue providing the Classic service.
Classic service.
Low Latency, Low Loss, and Scalable throughput (L4S) service: The Low Latency, Low Loss, and Scalable throughput (L4S) service: The
'L4S' service is intended for traffic from Scalable congestion 'L4S' service is intended for traffic from Scalable congestion
control algorithms, such as the Prague congestion control control algorithms, such as the Prague congestion control
[PRAGUE-CC], which was derived from DCTCP [RFC8257]. The L4S [PRAGUE-CC], which was derived from DCTCP [RFC8257]. The L4S
service is for more general traffic than just Prague -- it allows service is for more general traffic than just Prague -- it allows
the set of congestion controls with similar scaling properties to the set of congestion controls with similar scaling properties to
Prague to evolve, such as the examples listed above (Relentless Prague to evolve, such as the examples listed below (Relentless
and SCReAM). The term 'L4S queue' means a queue providing the L4S and SCReAM). The term 'L4S queue' means a queue providing the L4S
service. service.
C: Abbreviation for Classic, e.g., when used as a subscript.
L: Abbreviation for L4S, e.g., when used as a subscript.
The terms Classic or L4S can also qualify other nouns, such as The terms Classic or L4S can also qualify other nouns, such as
'queue', 'codepoint', 'identifier', 'classification', 'packet', 'queue', 'codepoint', 'identifier', 'classification', 'packet',
and 'flow'. For example, an L4S packet means a packet with an L4S and 'flow'. For example, an L4S packet means a packet with an L4S
identifier sent from an L4S congestion control. identifier sent from an L4S congestion control.
Both Classic and L4S services can cope with a proportion of Both Classic and L4S services can cope with a proportion of
unresponsive or less-responsive traffic as well but, in the L4S unresponsive or less-responsive traffic as well but, in the L4S
case, its rate has to be smooth enough or low enough to not build case, its rate has to be smooth enough or low enough to not build
a queue (e.g., DNS, Voice over IP (VoIP), game sync datagrams, a queue (e.g., DNS, Voice over IP (VoIP), game sync datagrams,
etc.). etc.). The DualQ Coupled AQM behaviour is defined to be similar
to a single First-In, First-Out (FIFO) queue with respect to
unresponsive and overload traffic.
TESTING TESTING
Reno-friendly: The subset of Classic traffic that is friendly to the Reno-friendly: The subset of Classic traffic that is friendly to the
standard Reno congestion control defined for TCP in [RFC5681]. standard Reno congestion control defined for TCP in [RFC5681].
The TFRC spec [RFC5348] indirectly implies that 'friendly' is The TFRC spec [RFC5348] indirectly implies that 'friendly' is
defined as "generally within a factor of two of the sending rate defined as "generally within a factor of two of the sending rate
of a TCP flow under the same conditions". Reno-friendly is used of a TCP flow under the same conditions". Reno-friendly is used
here in place of 'TCP-friendly', given the latter has become here in place of 'TCP-friendly', given the latter has become
imprecise, because the TCP protocol is now used with so many imprecise, because the TCP protocol is now used with so many
different congestion control behaviours, and Reno is used in non- different congestion control behaviours, and Reno is used in non-
TCP transports, such as QUIC [RFC9000]. TCP transports, such as QUIC [RFC9000].
Classic ECN: The original Explicit Congestion Notification (ECN) Classic ECN: The original Explicit Congestion Notification (ECN)
protocol [RFC3168] that requires ECN signals to be treated as protocol [RFC3168] that requires ECN signals to be treated as
equivalent to drops, both when generated in the network and when equivalent to drops, both when generated in the network and when
responded to by the sender. responded to by the sender.
L4S uses the ECN field as an identifier with the names for the L4S uses the ECN field as an identifier with the names for the
four codepoints of the 2-bit IP-ECN field unchanged from those four codepoints of the 2-bit IP-ECN field unchanged from those
defined in the ECN spec [RFC3168], i.e., Not-ECT, ECT(0), ECT(1), defined in the ECN spec [RFC3168], i.e., Not-ECT, ECT(0), ECT(1),
and CE, where ECT stands for ECN-Capable Transport and CE stands and CE, where ECT stands for ECN-Capable Transport and CE stands
for Congestion Experienced. A packet marked with the CE codepoint for Congestion Experienced. A packet marked with the CE codepoint
is termed 'ECN-marked' or sometimes just 'marked' where the is termed 'ECN-marked' or sometimes just 'marked' where the
context makes ECN obvious. context makes ECN obvious.
Site: A home, mobile device, small enterprise, or campus where the
network bottleneck is typically the access link to the site. Not
all network arrangements fit this model, but it is a useful,
widely applicable generalization.
 End of changes. 6 change blocks. 
7 lines changed or deleted 13 lines changed or added

This html diff was produced by rfcdiff 1.48.