VIVOTEK
User's Manual - 87
QoS/DSCP (the DiffServ model)
DSCP-ECN defines QoS at Layer 3 (Network Layer). The Differentiated Services (DiffServ) model is
based on packet marking and router queuing disciplines. The marking is done by adding a field to the
IP header, called the DSCP (Differentiated Services Codepoint). This is a 6-bit field that provides 64
different class IDs. It gives an indication of how a given packet is to be forwarded, known as the Per Hop
Behavior (PHB). The PHB describes a particular service level in terms of bandwidth, queueing theory,
and dropping (discarding the packet) decisions. Routers at each network node classify packets according
to their DSCP value and give them a particular forwarding treatment; for example, how much bandwidth
to reserve for it.
Below are the setting options of DSCP (DiffServ Codepoint). Specify the DSCP value for each application
(0~63).
Note that different vendors of network devices might have different methodologies and unique
implementations. Shown below is a sample corresponding information from a Cisco switch. You should
enter a DSCP tag value according to the information provided by the network devices.
32
QoS Baseline/Technical Marketing Classification and Marking Recommendations
Application
Layer3 Classification
Layer 2 CoS/MPLS EXP
IPP
PHB
DSCP
IP Routing
6
CS6
48
6
Voice
5
EF
46
5
Interactive Video
4
AF41
34
4
QoS B
Streaming-Video
4
CS4
32
4
Locally-defined Mission-
Critical Data
3
-
25
3
Call-signaling
3
AF31/CS3
26/24
3
Transactional Data
2
AF21
18
2
Network Management
2
CS2
16
2
Bulk Data
1
AF11
10
1
Scavenger
1
CS1
8
1
Best Effort
0
0
0
0
