D-Link 3312SR Reference Manual - Page 97

DGS-3312SR Layer 3 Gigabit Switch 13 QOS COMMANDS The DGS-3312SR switch supports 802.1p priority queuing. The switch has nine hardware priority queues, one of which is internal and not configurable. These hardware priority queues are numbered from 7 (Class 7) - the highest hardware priority queue - to 0 (Class 0) - the lowest hardware priority queue. The eight priority tags specified in IEEE 802.1p (p0 to p7) are mapped to the switch's hardware priority queues as follows: • Priority 0 is assigned to the Switch's Q2 queue. • Priority 1 is assigned to the Switch's Q0 queue. • Priority 2 is assigned to the Switch's Q1 queue. • Priority 3 is assigned to the Switch's Q3 queue. • Priority 4 is assigned to the Switch's Q4 queue. • Priority 5 is assigned to the Switch's Q5 queue. • Priority 6 is assigned to the Switch's Q6 queue. • Priority 7 is assigned to the Switch's Q7 queue. For strict priority-based scheduling, any packets residing in the higher priority queues are transmitted first. Multiple strict priority queues empty based on their priority tags. Only when these queues are empty, are packets of lower priority transmitted. For round-robin queuing, the number of packets sent from each priority queue depends upon the assigned weight. For a configuration of 8 CoS queues, A~H with their respective weight value: 8~1, the packets are sent in the following sequence: A1, B1, C1, D1, E1, F1, G1, H1, A2, B2, C2, D2, E2, F2, G2, A3, B3, C3, D3, E3, F3, A4, B4, C4, D4, E4, A5, B5, C5, D5, A6, B6, C6, A7, B7, A8, A1, B1, C1, D1, E1, F1, G1, H1. For round-robin queuing, if each CoS queue has the same weight value, then each CoS queue has an equal opportunity to send packets just like round-robin queuing. For round-robin queuing, if the weight for a CoS is set to 0, then it will continue processing the packets from this CoS until there are no more packets for this CoS. The other CoS queues that have been given a nonzero value, and depending upon the weight, will follow a common round-robin scheme. Remember that the switch has 8 priority queues (and eight Classes of Service) for each port on the Switch. The commands in the Command Line Interface (CLI) are listed (along with the appropriate parameters) in the following table. NOTE: As a stand-alone switch or as a master switch in a switch stack, the switch number will be referred to as 15 for all configurations, graphs and tables. Command config bandwidth_control show bandwidth_control config 802.1p user_priority show 802.1p user_priority config 802.1p default_priority Parameters [ | all] {rx_rate [no_limit | ] | tx_rate [no_limit ]} {} { } [ | all] | 91