target = "https://www.rfc-editor.org/rfc/rfc8312#section-4.6"

# 4.6.  Fast Convergence
#
# To improve the convergence speed of CUBIC, we add a heuristic in
# CUBIC.  When a new flow joins the network, existing flows in the
# network need to give up some of their bandwidth to allow the new flow
# some room for growth if the existing flows have been using all the
# bandwidth of the network.  To speed up this bandwidth release by
# existing flows, the following mechanism called "fast convergence"
# SHOULD be implemented.
# 
# With fast convergence, when a congestion event occurs, before the
# window reduction of the congestion window, a flow remembers the last
# value of W_max before it updates W_max for the current congestion
# event.  Let us call the last value of W_max to be W_last_max.
# 
#    if (W_max < W_last_max){ // should we make room for others
#        W_last_max = W_max;             // remember the last W_max
#        W_max = W_max*(1.0+beta_cubic)/2.0; // further reduce W_max
#    } else {
#        W_last_max = W_max              // remember the last W_max
#    }
# 
# At a congestion event, if the current value of W_max is less than
# W_last_max, this indicates that the saturation point experienced by
# this flow is getting reduced because of the change in available
# bandwidth.  Then we allow this flow to release more bandwidth by
# reducing W_max further.  This action effectively lengthens the time
# for this flow to increase its congestion window because the reduced
# W_max forces the flow to have the plateau earlier.  This allows more
# time for the new flow to catch up to its congestion window size.
# 
# The fast convergence is designed for network environments with
# multiple CUBIC flows.  In network environments with only a single
# CUBIC flow and without any other traffic, the fast convergence SHOULD
# be disabled.

[[spec]]
level = "SHOULD"
quote = '''
To speed up this bandwidth release by
existing flows, the following mechanism called "fast convergence"
SHOULD be implemented.
'''

[[spec]]
level = "SHOULD"
quote = '''
In network environments with only a single
CUBIC flow and without any other traffic, the fast convergence SHOULD
be disabled.
'''