Quality Of Service General Settings - ZyXEL Communications VMG Series User Manual

The Zyxel Device supports three incoming traffic metering algorithms: Token Bucket Filter (TBF), Single
Rate Two Color Maker (srTCM), and Two Rate Two Color Marker (trTCM). You can specify actions which
are performed on the colored packets. See
metering algorithm.
Strictly Priority
Strictly Priority (SP) services queues based on priority only. As traffic comes into the Switch, traffic on the
highest priority queue, Q7 is transmitted first. When that queue empties, traffic on the next highest priority
queue, Q6 is transmitted until Q6 empties, and then traffic is transmitted on Q5 and so on. If higher
priority queues never empty, then traffic on lower priority queues never gets sent. SP does not
automatically adapt to changing network requirements.
Weighted Round Robin Schedule (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 Scheduling (WRR) 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.

12.3 Quality of Service General Settings

Use this screen to enable or disable QoS and set the upstream bandwidth or assign traffic priority. See
Section 12.1 on page 277
When one of the following situations happens, the current WAN linkup rate will be used instead:
WAN Managed Upstream Bandwidth is set to 0
1
WAN Managed Upstream Bandwidth is empty
2
WAN Managed Upstream Bandwidth is higher than the current WAN interface linkup rate
3
Note: Manually defined QoS is ignored when Upstream Traffic Priority is selected.
Note: Upstream Traffic Priority automatically assigns a traffic priority level based on the
selected criteria.
Note: To have your QoS settings configured in other QoS screens take effect, select None in
the Upstream Traffic Priority Assigned by field.
Click Network Setting > QoS > General to open the screen as shown next.
Chapter 12 Quality of Service (QoS)
Section 12.8 on page 294
for more information.
VMG/EMG/AM/DM/GM Series User's Guide
279
for more information on each