Comtech EF Data CDM-625A - Manual (Page 729)

CDM-625A Advanced Satellite Modem MN-CDM625A
Appendix R Revision 3
R–7
• Port 3 priority is set to 3;
• Ports 2 and 4 priorities are set to trunk mode (native disabled).
3) The modem data rate is set to 4000 Kbps.
4) The ingress traffic on Port 1 is set to 2 Mbps.
5) The ingress traffic on Port 3 is set to 1600 Kbps.
6) The ingress traffic on Port 2 is set to 2000 Kbps with a VLAN Priority of 1.
7) The ingress traffic on Port 4 is set to 800 Kbps with a VLAN Priority of 7.
QUESTION: What is the total output data rate and what are the individual port output data
rates?
ANSWER “A” – For HW Ver. Rev 2.1 and newer:
• Based on Table R-1 for a modem Tx bandwidth of 4 Mbps, the QoS output bandwidth is set
to 4 Mbps.
• Since the modem Tx bandwidth and QoS output data rates are the same, there is no need
for normalization.
• Based on Table R-2, the VLAN Priorities 7 and 1 are mapped, respectively, to L2 QoS
Priorities 4 and 1.
• The data rate for each port is as follows:
Port
VLAN
Priority
L2 QoS
Priority
Input Data Rate
QoS Output Data Rate
= Modem Output Data
Rate
Remaining Data Rate (After
Serving the Priority Queue)
4 7 (b111) 4 800 Kbps 800 Kbps 3200 Kbps
3 N/A 3 1600 Kbps 1600 Kbps 1600 Kbps
2 1 (b001) 1 2 Mbps 800Kbps 800Kbps
1 N/A 1 2 Mbps 800 Kbps 800 Kbps
Total ► 5.3 Mbps 4 Mbps 0 Mbps
1) Layer 2 QoS can be enabled only when the optional Packet Processor is
not enabled.
2)
Layer 2 QoS is implemented on System on Chip (SoC) hardware with a
total queue memory of 1 Mbits (128 Kbytes). Layer 2 QoS therefore
cannot accept traffic bursts requiring more than 128 Kbytes of storage.