Comtech EF Data CDM-570/L Vipersat Parameter Editor - Manual (Page 36)

Network
2-20 CDM-570/L, CDD-56X Parameter Editor User Guide
Expedited Forwarding and Assured Forwarding DSCP
Another implementation of DiffServ uses all 6 bits of the DSCP to define Expe-
dited and Assured Forwarding, as shown in table 2-2.
Expedited Forwarding (EF) DSCP
This defines premium service and is recommended for real time traffic applica-
tions such as VoIP and video conferencing.
Assured Forwarding (AF) DSCP
This defines four service levels and also uses the last three bits of the DSCP to
define the Drop Precedence (Low, Medium, or High). The Drop Precedence
determines which packets will most likely be dropped during periods of over
congestion, similar to WRED. As a result, each of the four AF service levels
also have three Drop Precedence levels for which the modem/router provides 12
separate queues.
Minimum Bandwidth (AF only)
The minimum bandwidth specification can be assigned to a flow that allows a
committed information rate (CIR) to be applied to user-defined classes of traf-
fic, or the default of no minimum bandwidth can be selected.
Maximum Bandwidth (AF only)
This can be assigned to a flow to restrict the maximum bandwidth that any
particular flow will utilize, or the default of no bandwidth restriction can be
selected.
Note: Minimum and Maximum Bandwidth is only configurable for each of the
four Assured Forwarding classes.
Table 2-2 Expedited and Assured Forwarding, DSCP
DiffServ Type Class Selector DSCP
Modem/Router
Priority
Expedited Forwarding Precedence 1 101 110 1
Assured Forwarding – Class 1 Precedence 8 001 xx0 8
Assured Forwarding – Class 2 Precedence 8 010 xx0 8
Assured Forwarding – Class 3 Precedence 8 011 xx0 8
Assured Forwarding – Class 4 Precedence 8 100 xx0 8
NOTE