Patton electronic CopperLink 2160 Series - Manual (Page 53)

Advanced Configuration Options 53
Model 2160 Series Getting Started Guide 4 • Web configuration
Figure 26. Service by WRR
IP DSCP Priority
Differentiated Services Overview. Differentiated Services (DiffServ) is a class of service (CoS) model that
enhances best-effort Internet services by differentiating traffic by users, service requirements and other criteria.
Packets are specifically marked, allowing network nodes to provide different levels of service, as appropriate for
video playback, voice calls or other delay-sensitive applications, via priority queuing or bandwidth allocation.
DiffServ defines a new DS (Differentiated Services) field to replace the Type of Service (ToS) field in the IP
header. The DS field contains a 2-bits unused field and 6-bits DSCP field which can define up to 64 service
levels.
Figure 27 shows the DS field:
Figure 27. Differentiated Services field
The DSCP value used to identify 64 levels (26=64) of service determines the forwarding behavior that each
packet gets across the DiffServ network. Based on the marking rule different kinds of traffic can be marked for
different priorities of forwarding. Resources can then be allocated according to the DSCP values and the con-
figured policies.
Table 11 shows how the bits are used in the DSCP field.
6,7 Queue 3
4,5 Queue 2 4,5 Queue 2
4,5 Queue 2 0,3 Queue 1
4,5 Queue 2 1,2 Queue 0