66 MN.00273.E - 004
Fig.21 - Red curve
Once WRed is enabled the threshold of S
min
S
max
and P
max
for the Green and Yellow frames have to be set.
The value set the points of the curve shown in Fig.21
. There are some predetermined profiles to be ena-
bled:
• Profile 1:
-S
min
= 30
-S
max
=60
-P
max
=10
• Profile 2:
-S
min
= 20
-S
max
=40
-P
max
=10
These profiles can be set for the Yellow Frames (Y) and Green Frames (G) as well. These values represent:
•S
min
: represents the threshold after which the switch starts dropping packets
•S
man
and P
max
: are the thresholds that makes the curve of “Drop Percentage”/”Average Queue Oc-
cupation” change. After this point the dropping packets increase rapidly.
• “Red Gentle”: after the point represented by S
max
and P
max
: the Drop percentage can increase to
a 100% (RED) or can linearly increase. the choice of how to increase, directly or linearly to a 100%
is manage by disabling or enabling the RED Gentle.
• RED (Random Early Drop): no packet are dropped until Average Queue Occupation % reaches
Smin(G, Green), packets are dropped randomly until a percentage of Pmax and an Occupation %
of Smax(G) limits are reached, all packets are dropped over an Occupation % higher than Smax(G);
• RED Gentle (Enable): no packets are dropped until Average Queue Occupation % reaches Smin(G,
Green); with Average Queue Occupation % higher than Smin(G) and lower than Smax(G), packets
are dropped randomly with a percentage defined by the straight line between Smin(G)/0 and
Smax(G)/Pmax(G); with Average Queue Occupation % higher than Smax(G) the percentage of ran-
domly dropped packets is defined by the straight line between Smax(G)/Pmax(G) and Sgentle(G)/
100%;
• WRED (Weighted Random Early Drop): Weighted RED is a two line RED; one line for Green packets,
one line for Yellow packets; Green and Yellow are defined by CIR and EIR into Input Filtering Policy
(Lan1,2,3,4);
no green packet is dropped until Average Queue Occupation % reaches Smin(G, Green);
no yellow packet is dropped until Average Queue Occupation % reaches Smin (Y, Yellow);
with Average Queue Occupation % higher than Smin(G) and lower than Smax(G) green packets are
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