Table of Contents
Advertisement
QoS Example 3
SETUP:
•
•
•
•
•
•
QUESTION:
What is the total output data rate and what are the individual port output data rates?
ANSWER:
•
•
Port
2
3
2
1
Total ►
*After Priority 4, even though the actual modem TX data rate is 2500 kbps, the QoS leftover
data rate is still 2500 kbps since QoS bandwidth is 3000 kbps.
Appendix M
Port-based Layer 2 QoS mode is selected.
Port Layer 2 QoS Priorities are set as follows:
Port 1 priority is set to 1
o
Port 2 priority is set to 2
o
Port 3 priority is set to 3
o
Port 4 priority is set to 4
o
The modem data rate is set to 2500 Kbps.
The ingress traffic on Ports 1 and 2 are set to 2 Mbps.
The ingress traffic on Port 3 is set to 800 Kbps.
The ingress traffic on Port 4 is set to 500 Kbps.
Based on Table M-1 for a modem Tx bandwidth of 2.5 Mbps, the QoS output
bandwidth is set to 3 Mbps.
Since the modem Tx bandwidth and QoS output data rates are not the same,
after Layer 2 QoS prioritization the modem will further limit the output data rate to
the Tx bandwidth of the mode. The individual port data rates will henceforth be
trimmed (normalized) to the data rate of the modem Tx bandwidth without
considering the priorities.
L2 QoS
Input
QoS Output
Priority
Data Rate
Data Rate
4
500 Kbps
500 Kbps
3
800 Kbps
800 Kbps
2
2 Mbps
1700 Kbps
1
2 Mbps
5.3 Mbps
Remaining Data
Rate* (After Serving
the Priority Queue)
2500 Kbps
1700 Kbps
0 Kbps
0 Kbps
0 Kbps
3 Mbps
0 Kbps
M–4
CDM-425 Advanced Satellite Modem
Output Data Rate
500 x (2.5/3) = 417 Kbps
800 x (2.5/3) = 667 Kbps
1700 x (2.5 /3) = 1416 Kbps
0 Kbps
2.5 Mbps
MN-CDM-425
Revision 0
Advertisement
Table of Contents
