target = "https://www.rfc-editor.org/rfc/rfc9000#section-13.2.2"

# 13.2.2.  Acknowledgment Frequency
#
# A receiver determines how frequently to send acknowledgments in
# response to ack-eliciting packets.  This determination involves a
# trade-off.
# 
# Endpoints rely on timely acknowledgment to detect loss; see Section 6
# of [QUIC-RECOVERY].  Window-based congestion controllers, such as the
# one described in Section 7 of [QUIC-RECOVERY], rely on
# acknowledgments to manage their congestion window.  In both cases,
# delaying acknowledgments can adversely affect performance.
# 
# On the other hand, reducing the frequency of packets that carry only
# acknowledgments reduces packet transmission and processing cost at
# both endpoints.  It can improve connection throughput on severely
# asymmetric links and reduce the volume of acknowledgment traffic
# using return path capacity; see Section 3 of [RFC3449].
# 
# A receiver SHOULD send an ACK frame after receiving at least two ack-
# eliciting packets.  This recommendation is general in nature and
# consistent with recommendations for TCP endpoint behavior [RFC5681].
# Knowledge of network conditions, knowledge of the peer's congestion
# controller, or further research and experimentation might suggest
# alternative acknowledgment strategies with better performance
# characteristics.
# 
# A receiver MAY process multiple available packets before determining
# whether to send an ACK frame in response.

[[spec]]
level = "SHOULD"
quote = '''
A receiver SHOULD send an ACK frame after receiving at least two ack-
eliciting packets.
'''

[[spec]]
level = "MAY"
quote = '''
A receiver MAY process multiple available packets before determining
whether to send an ACK frame in response.
'''