PLANET XGS3-24042 - Manual (Page 180)

20-17
20.1.2 Basic Egress QoS Model
Classification scheduling Remark Policing
Generate
internal
priority
Ingress Egress
color
Sort packet traffic
according to the
classification info and
convert classification info
to internal priority value
and drop precedence
value
Decide whether traffic
color is single bucket
dual color or dual
bucket three color
according policing
policy
Degrade or discard
different color packets,
and remark DSCP,
TOS, COS fields
Place packets into priority
queues according to
internal priority, provide
the service for them
according to queue weight
and drop precedence
Policing and
remark of
Egress
Set the color of packet
traffic according to policing
policy of Egress
PolicyMap, degrade or
drop different color
packets
According to the characters (including field values like COS and DSCP) of upstream packets, policing and
rewriting of Egress make the last QoS change on the packet prior to the packet egress.
Policing configures different policing policy based on the flow and distributes bandwidth for the flow classified.
The distribution policy of bandwidth can be either dual bucket dual color or dual bucket three color. Different
colors can be assigned to different flows and approaches of discard or passage can be chosen for them; you
can add rewriting action for packets with passage approach chosen. See the following flow chart for detailed
description of Egress QoS: