Samsung Ubigate iBG3026, Руководство по настройке

Страница: 222 / 718

CHAPTER 19. QoS
184
© SAMSUNG Electronics Co., Ltd.
In the color aware mode, packet is assumed to be pre-colored. In this case
when packet of size B bytes arrives for policing, if Tp(t)-B < 0 and packet
color is green or yellow, then the packet marked red else if Tc(t)-B < 0 and
packet color green then the packet marked yellow and Tp is decremented by B
else packet’s color is unchanged and both Tc and Tp are decremented by B.
Figure 19.6 Two Rate Three Color Marking
The CIR and PIR will be specified in Kbps. CBS and PBS will be specified in
Kbits. CBT and PBT are defined by the relationships(CIR = CBS/CBT) and
(PIR = PBS/PBT). The period of the token filling process should at least be
equal to the lesser of CBT and PBT milliseconds. Without which CIR and PIR
cannot be sustained. It is recommended that CBS and PBS be large enough so
that CBT and PBT are at least 1 second.
Is Tc full?
Get
‘pkt size’ number
of tokens
Tc
No
tokens
Green packet
Green action
Permit/mark-dscp/
drop
Packets sent for further processing
Yes
Insufficient
tokens
Is Tc full?
Get
‘pkt size’ number
of tokens
Tp
No
tokens
Yes
Drop
Token Bucket(Tp)
Size = PBS
(PBS >= CBS)
Token Replenish
Process Fill tokens
at rate = CIR
Executes every 100ms
Token Bucket(Tc)
Size = CBS
Packet
classification
Packet arrival
Out-of profile
packet
Red packet
Red action
Permit/mark-dscp/
drop
Yellow packet
Yellow action
Permit/mark-dscp/
drop
Yes
Token Replenish
Process Fill tokens
at rate = PIR
Executes every 100ms
(PIR >= CIR)