Weighted round robin priority scheduling, Table 3. example of weighted round robin priority – Allied Telesis AT-S88 User Manual

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AT-S88 Management Software User’s Guide

With this type of scheduling, a port transmits all packets out of higher
priority queues before transmitting any from the lower priority queues. For
instance, as long as there are packets in Q3 it does not handle any
packets in Q2.

The value to this type of scheduling is that high priority packets are always
handled before low priority packets.

The problem with this method is that some low priority packets might never
be transmitted out the port because a port might never get to the low
priority queues. A port handling a large volume of high priority traffic may
be so busy transmitting the high priority packets that traffic that it never
has an opportunity to get to any packets that are stored in its low priority
queues.

Weighted Round Robin Priority Scheduling

The weighted round robin (WRR) scheduling method functions as its name
implies. The port transmits a set number of packets from each queue, in a
round robin fashion, so that each has a chance to transmit traffic. This
method guarantees that every queue receives some attention from the
port for transmitting packets.

Table 3 shows the WRR factory default settings for the number of packets
transmitted from each queue.

Table 3. Example of Weighted Round Robin Priority

Port Egress Queue

Maximum Number of

Packets