Comtech EF Data SLM-5650A Vipersat Parameter Editor - Manual (Page 56)

WAN
2-40 SLM-5650A Parameter Editor User Guide
Quality of Service
For network modems utilizing QoS, activate the Enable Quality of Service
check box, then click on the Diff Serv sub-menu item to configure the Per-Hop
Behavior categories.
Differentiated Services Code Point (DSCP)
The Comtech EF Data implementation of DiffServ uses all six bits of the DSCP
(the first six bits of the ToS field in the IP Header) to define the Per-Hop Behav-
ior categories, as shown in table 2-2. There are seven categories for defining
Per-Hop Behavior: Class Selector 6, Expedited Forwarding, Assured Forward-
ing Class 1 through 4, and Default.
The SLM-5650A will prioritize the traffic based upon the DSCP Class Selector
Precedence. The Precedence value, also referred to as the Class, is determined
from the three most significant bits in the DiffServ field. The Drop Probabilities
are determined by the three least significant bits (note that the LSB is always 0).
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 Prece-
dence of 0 (lowest priority).
Typically, DiffServ is implemented using exclusively Class Selector DSCP or
exclusively Expedited and Assured Forwarding DSCP. The SLM-5650A is
fully DiffServ compliant and will work with either DiffServ implementation or
with a combination of both.
Select the desired PHB category by clicking on the tab appearances in the Diff
Serv dialog (figure 2-27).
The Service Rate and Maximum Queue Depth parameters are common to all
categories and are described below.
Table 2-2 Differentiated Services, DSCP
Per-Hop Behavior
Sevice Rate
(Kbps) DSCP
SLM-5650A
Priority
Default Best Effort 000 000 4
Assured Forwarding – Class 1 Best Effort 001 xx0 3
Assured Forwarding – Class 2 Variable 010 xx0 3
Assured Forwarding – Class 3 Variable 011 xx0 3
Assured Forwarding – Class 4 Variable 100 xx0 3
Expedited Forwarding 2048.000 101 110 2
Class Selector 6 2048.000 110 000 1
NOTE