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Publication date: Mar., 2012
Revision A1
way. There is a one to one mapping between QoS class, queue and priority. A QoS class of
0 (zero) has the lowest priority.
DP level :
Controls the default DP level, i.e., the DP level for frames not classified in any other way.
PCP :
Controls the default PCP for untagged frames.
DEI :
Controls the default DEI for untagged frames.
Tag Class. :
Shows the classification mode for tagged frames on this port.
Disabled:
Use default QoS class and DP level for tagged frames.
Enabled:
Use mapped versions of PCP and DEI for tagged frames.
Click on the mode in order to configure the mode and/or mapping.
DSCP Based :
Click to Enable DSCP Based QoS Ingress Port Classification.
Buttons:
Save – Click to save changes.
Reset- Click to undo any changes made locally and revert to previously saved
values.
N
OTE
:
DP level : Every incoming frame is classified to a Drop
Precedence Level (DP level), which is used throughout the
device for providing congestion control guarantees to the
frame according to what was configured for that specific DP
level.
PCP : PCP is an acronym for Priority Code Point. It is a 3-bit
field storing the priority level for the 802.1Q frame.
DEI : DEI is an acronym for Drop Eligible Indicator. It is a 1-
bit field in the VLAN tag.
Actual PCP is Pri column in Vlan tag packet , DEI is cfi
column
PCP value from 0~7 , it can be used for priority definition .
DEI value is 0 or 1 , it is settable , map to DP value is 0 or
1.
When ingress Qos class value is the same , then through
DP level value to define the priority , DP value larger will be
dropped first.
ex: From Port 1 input 1G Pkts , Egress Port 7 Rate be set
with 500M . Port 1 Pkts will includes two kinds packet:
a.
PCP & DEI = 0 0 , via configured map to Qos class & DP
level = 1 , 0
b.
PCP & DEI = 0 1 , via configured map to Qos class & DP
level = 1 , 1
Result will find (a) Packet all past, and (b) packets all drop
Содержание SM10P
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