Installation and User Manual
EtherHaul
1200™
EH-INST-02, Issue 4.0
Page 83
Figure
7-5 Ingress-COS Setup
7.1.3
QoS Scheduling
The EtherHaul 1200 QoS mechanism operates according to the following scheduling
mechanisms:
Strict Priority
- Lower priority packets are served only if all higher priority
queues are empty.
Weighted Fair Queuing (WFQ)
– Weights can be assigned to the radio
queues, assuring fairness between the queues.
Shaper
– Sets the CIR (Committed Information Rate, i.e., the maximum rate)
of the queues, with Strict Priority or WFQ
The default scheduling mode is Strict Priority.
When configuring the egress-cos, color-drop blind or aware can be configured.
7.1.3.1
Weighted Fair Queue (WFQ)
Weighted Fair Queuing (WFQ) can be used to provide different rates to different flows
while maintaining fairness in order to avoid starvation. WFQ is a data packet scheduling
technique that provides different scheduling priorities to statistically multiplexed data
flows.
If the link data rate is R, weights of N data flows are W1,W2,…,Wn, the i’th data flow will
achieve an average data rate of:
R*Wi / (W1 + W2 + … + Wn)
WFQ explicitly considers data queue, and by regulating the weights dynamically, WFQ
can be utilized to control the QoS.
WFQ can only be configured for ETH0 queues 1 through 5. The highest queues, 6 and 7,
are Strict Priority queues, and the lowest queue (0) is best effort.
