Quality Of Service - Comtech EF Data CDM-570 Installation And Operation Manual

CDM-570/570L Satellite Modem with Optional IP Module
IP Module Ethernet Interface Overview
15.4.4

Quality of Service

Quality of Service (QoS) is an optional feature of the IP Module. The user may select one
of three modes of QoS operation:
•
Mode 1 – QoS Rules based on Maximum Bandwidth and Priority
•
Mode 2 – QoS Rules based on Minimum and Maximum Bandwidth
•
Mode 3 – DiffServ
QoS Segmentation and Reassembly (SAR) - Packet Segmentation and Reassembly
(SAR) is enabled automatically while QoS is enabled. However, SAR is an adaptive
process; it will trigger only if the packet latency exceeds the threshold value (default to
20 msec). Latency value is calculated based on the satellite transmission bandwidth. The
minimum segment size was limited to 480 bytes excluding satellite HDLC header in
order to avoid satellite overhead and consumption of CPU cycles.
15.4.4.1 Maximum Bandwidth/Priority QoS Mode
QoS Rules can be assigned to up to 32 different types of flows to be defined by the user.
Flows can be defined by any combination of Protocol (FTP, UDP, RTP, etc.),
Source/Destination IP (specific or range), and/or Layer 3 Source/Destination Port.
Priority - A Priority level from 1 to 8 is assigned for each flow. The IP Module classifies
each packet that is to be forwarded over the satellite. The packet will then have a Priority
assigned according to the defined QoS Rules. Any packet that does not meet a QoS Rule
is assigned to the Default Rule and will be assigned a Priority of 8. Priority 1 packets will
be forwarded immediately, Priority 2 packets will be forwarded as soon as there are no
Algorithm Payload size
ADLC 1000
ADLC 500
ADLC 100
LZS 1472
LZS 1000
LZS 500
LZS 100
LZS 1472
LZS 1000
LZS 500
LZS 100
15–8
File Set Ratio
Canterbury 1.72
Canterbury 1.74
Canterbury 2.04
Calgary 1.66
Calgary 1.66
Calgary 1.68
Calgary 1.97
Canterbury 1.61
Canterbury 1.62
Canterbury 1.63
Canterbury 1.91
Revision 3
MN/CDM570L.IOM