ZyXEL GS-1548 User Guide - Page 68

Chapter 11 QoS 11.1.2 Strict Priority Strict priority scheduling singles out the highest priority queue and ensures all queued traffic in this queue is transmitted before servicing the lower priority queues. Strict priority scheduling services the remaining queues using WRR. As traffic comes into the Switch, traffic on the highest priority queue, Queue 3 is transmitted first. Only when that queue empties, traffic on the lower priority queues is transmitted using WRR scheduling. 11.2 QoS Enhancement You can configure the Switch to prioritize traffic even if the incoming packets are not marked with IEEE 802.1p priority tags or change the existing priority tags based on the criteria you select. The Switch allows you to choose one of the following methods for assigning priority to incoming packets on the Switch: Port Based QoS - Assign priority to packets based on the incoming port on the Switch. See Section 11.4.1 on page 71. DSCP Based QoS - Assign priority to packets based on their Differentiated Services Code Points (DSCPs). See Section 11.4.2 on page 72. ToS Based QoS - Assign priority to packets based on their Type of Service (ToS) tagging. See Section 11.4.5 on page 74. IP Address Based QoS - Assign priority to packets based on their IP address. See Section 11.4.6 on page 75. Note: Advanced QoS methods only affect the internal priority queue mapping for the Switch. The Switch does not modify the IEEE 802.1p value for the egress frames. You can choose one of these ways to alter the way incoming packets are prioritized or you can choose not to use any QoS enhancement setting on the Switch. 68 GS-1524/GS-1548 User's Guide