5-4z The allocable bandwidth (allocable bandwidth = the total bandwidth – the sum of the minimumguaranteed bandwidth for each queue) is divided and allocated to each queue based on queueprecedence.For example, assume that the total bandwidth of an interface is 10 Mbps and there are five flows on theinterface, with the precedence being 0, 1, 2, 3, and 4 respectively and the minimum guaranteedbandwidth being 128 kbps, 128 kbps, 128 kbps, 64 kbps, and 64 kbps respectively. Then,z The allocable bandwidth = 10 Mbps – (128 + 128 + 128 + 64 + 64) kbps = 9.5 Mbpsz The total allocable bandwidth quota is the sum of all the (precedence value + 1)s, that is, 1 + 2 + 3+ 4 + 5 = 15.z The bandwidth percentage assigned to each flow is (precedence value of the flow + 1)/totalallocable bandwidth quota. The bandwidth percentages for flows are 1/15, 2/15, 3/15, 4/15, and5/15 respectively.z The bandwidth allocated to a queue = Minimum guaranteed bandwidth + bandwidth allocated tothe queue from the allocable bandwidthBecause WFQ can balance the delay and jitter of every flow when congestion occurs, it is effectivelyapplied in some special occasions. For example, WFQ is adopted in the assured forwarding (AF)services of the Resource Reservation Protocol (RSVP). In Generic Traffic Shaping (GTS), WFQ is usedto schedule buffered packets.4) SP+WRR queue scheduling algorithmYou can implement SP+WRR queue scheduling on a port by assigning some queues on the port to theSP scheduling group and the others to the WRR scheduling group (that is, group 1). Packets in the SPscheduling group are scheduled preferentially. When the SP scheduling group is empty, packets in theWRR scheduling group are scheduled. Queues in the SP scheduling group are scheduled by SP.Queues in the WRR scheduling group are scheduled by WRR.Configuring an SP QueueBy default, WRR queue scheduling algorithm is adopted on all the ports. You can adopt SP queuescheduling algorithm instead as required.Configuration ProcedureFollow these steps to configure SP queues:To do… Use the command… RemarksEnter system view system-view —Enter portviewinterface interface-typeinterface-numberEnterport viewor portgroupviewEnter portgroupviewport-group manualport-group-namePerform either of the two operations.The configuration performed in Ethernetinterface view applies to the current portonly. The configuration performed in portgroup view applies to all the ports in theport group.Configure SP queuescheduling algorithm qos spRequiredBy default, all the ports adopt the WRRqueue scheduling algorithm, with theweight values assigned to queue 0 throughqueue 7 being 1, 2, 3, 4, 5, 9, 13, and 15.
