ZyXEL Communications GS1510-16 -, User Manual

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Chapter 15 QoS
GS1510 Series User’s Guide
86
15.3.1.1 Weighted Round Robin (WRR)
Round Robin scheduling services queues on a rotating basis and is activated only
when a port has more traffic than it can handle. A queue is given an amount of
bandwidth irrespective of the incoming traffic on that port. This queue then moves
to the back of the list. The next queue is given an equal amount of bandwidth, and
then moves to the end of the list; and so on, depending on the number of queues
being used. This works in a looping fashion until a queue is empty.
Weighted Round Robin (WRR) scheduling uses the same algorithm as round robin
scheduling, but services queues based on their priority and queue weight (the
number you configure in the queue
Weight field) rather than a fixed amount of
bandwidth. WRR is activated only when a port has more traffic than it can handle.
Queues with larger weights get more service than queues with smaller weights.
This queuing mechanism is highly efficient in that it divides any available
bandwidth across the different traffic queues and returns to queues that have not
yet emptied.
15.3.2 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 15.4 on page 86 .
DSCP Based QoS - Assign priority to packets based on their Differentiated
Services Code Points (DSCPs). See Section 15.5.1 on page 88 .
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.
15.4 Port Priority
Use the Port Priority screen to specify IEEE 802.1p priority for each port. Packets
without 802.1p priority tags will be applied the priority settings according to the