Using OmniStream
™
with Velocity
™
Device Manager
146
Appendix
Differentiated Services Code Point
(DSCP) is a method of managing network traffic, in addition to providing
Quality
of Service
(QoS) within the Layer-3 (Network Layer) of the OSI network model. DSCP uses the 6-bit Differentiated
Services (DS) field in the IP header in order to determine packet classification/priority. Normally, all routers and
switches will forward network traffic to the proper destination with the same priority, no matter what type of data it is.
This methodology is what is known as
Best Effort
.
The
Best Effort
setting will provide normal priority for data packets, while other settings will raise the priority on
data packets. However, it should be noted that a higher priority setting on one type of data type may also result in
data packet loss for other data types, depending upon network traffic.
When QoS or differentiated services policy is used, all network devices such as routers, networks switches, and
end-devices must be configured properly in accordance with QoS policies on the network. There are two main
methodologies for tagging traffic:
Assured Forwarding (AF)
and
Class Selectors (CS)
.
The tables below provide a list of the available selections and their description.
IMPORTANT:
Consult the IT administrator as to what methods to use and the required settings
for each encoder on the network.
Differentiated Services Code Point
Selection
Queue Classification
Drop Probability
AF11
Class 1
Low
AF21
Class 2
Low
AF31
Class 3
Low
AF41
Class 4
Low
Selection
Class Selector Name
CS0 / Best Effort
Routine
CS1
Priority
CS2
Immediate
CS3
Flash
CS4
Flash Override
CS5
Critical
CS6
Interwork Control
CS7
Network Control
EF
Expedited Forwarding
Table 1 - Assured Forwarding
Table 2 - Class Selectors
