Qos Scheduling - UTStarcom iSpirit 3026 Manual

Further processing can be carried out to determine that PRI queue of class in-output ports when
the data flow is in In Profile status. Every class through classification steps will obtain one
internal DSCP value, and through DSCP-QUEUE Mapping Table will obtain PRI queue of output
port. All output ports of iSpirit 3026 switch support 4 PRI queues.
Class information value has been obtained at classification phase, there are three kinds of class
informations: COS class information, IP Precedence class information, and DSCP class
information. At output port need to modify data pazket relative field and add the class information
into data packet.
QoS trust port and untrust port on QoS policy have great differences, QoS trust port only need to
determine the PRI queue of data flow instead of any bandwidth limitations or generation of class
information values or modifying IP data packet head either. But QoS untrust port should do QoS
policy processing according to configuration of system ports to determine class information
value, and it is necessary to determine the PRI queue, but bandwidth limitations can be avoided.

5. QoS Scheduling

Output ports of iSpirit 3026 switch support 4 PRI queues, PRI of queue 1 is the lowest and that
of queue 4 is the highest. After the data flow is briefly kept in output queue, output port should
according to QoS scheduling do PRI processing for data flow to determine that the sending
command. Output ports of iSpirit 3026 switch support 3 kinds of QoS scheduling methods, as
follows:
SPQ: strictly based on PRI make scheduling for data flow, only after all data in high PRI queue
was sent out that in low PRI queue can be sent out, and the disadvantage is that data flow in low
PRI queue can be processed after a long time. RR: data flows of queue 1 and queue 4
according to the same weight carry out scheduling, in fact PRI of queue 1 and queue 4 is the
same, and the disadvantage is that service quality of important data can be ensured, in fact it is
the same with that without QoS. WRR: weight can be configured according to actual
requirement, output port according to the configured weight to make scheduling for data flow.
Which has remedied the deficiencies of SPQ and RR to ensure the service quality of important
data.
6. FFP Introduction
All port input of iSpirit 3026 switch has one FFP. FFP realizes classification and QoS policy. FFP
exists in the hardware logic, which will not influence the tranference efficiency of data flow when
the port is started with QoS configuration.