Comtech EF Data CDM-570L Installation And Operation Manual page 290

CDM-570/570L Satellite Modem with Optional IP Module
IP Module Ethernet Interface Overview
The IP Module will prioritize the traffic based upon the DSCP Class Selector Precedence.
Note: All traffic that does not have the DSCP Class Selector Precedence defined (000
000) will be placed in the Default Queue and have a Precedence of 9.
Expedited Forwarding and Assured Forwarding DSCP – Another implementation of
DiffServ uses all 6 bits of the DSCP to define Expedited and Assured Forwarding:
Expedited Forwarding
Assured Forwarding – Class 1
Assured Forwarding – Class 2
Assured Forwarding – Class 3
Assured Forwarding – Class 4
Expedited Forwarding (EF) DSCP – This defines premium service and is
recommended for real time traffic applications such as VoIP and video conferencing.
Assured Forwarding (AF) DSCP – This defines 4 service levels and also uses the last 3
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 Weighted Random Early Detection (WRED). As a result, each of
the 4 AF service levels also have 3 Drop Precedence levels for which the IP Module
provides 12 separate queues.
Minimum Bandwidth (AF only) - Minimum specification that allows a committed
information rate (CIR) to be applied to user defined classes of traffic, 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 4 Assured
Forwarding classes.
Note: Typically, DiffServ is implemented using exclusively Class Selector DSCP or exclusively
Expedited and Assured Forwarding DSCP. The IP Module is fully DiffServ compliant and
will work with either DiffServ implementation or with a combination of both.
DiffServ Type Class Selector DSCP
Precedence 1 101 110
Precedence 8 001 xx0
Precedence 8 010 xx0
Precedence 8 011 xx0
Precedence 8 100 xx0
15–14
Revision 4
MN/CDM570L.IOM
IP Module Priority
1
8
8
8
8