ZyXEL Communications VES-1124 -, User Manual

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VES-1124 User’s Guide
Queuing Method 17-1
Chapter 17
Queuing Method
This chapter introduces the switch’s queuing algorithms.
17.1 Introduction to Queuing
Queuing is used to help solve performance degradation when there is network congestion. Use the Queuing
Method screen to configure queuing algorithms for outgoing traffic. See also Priority Queue Assignment in
Switch Setup and Priority in Port Setup for related information.
Queuing algorithms allow switches to maintain separate queues for packets from each individual source or flow and
prevent a source from monopolizing the bandwidth.
The VES has two physical queues, high and low.
17.1.1 First Come First Serve
First come first serve queuing treats all traffic with the same priority. The switch transmits the traffic in the order it
receives it. The high-priority queue does not get any priority over the low-priority queue.
17.1.2 Strict Priority Queuing
Strict priority queuing services queues based on priority only. As traffic comes into the switch, traffic in the high-
priority queue is transmitted first. When the high-priority queue empties, traffic in the low-priority queue, is
transmitted until the low-priority queue empties. If the high-priority queue never empties, then traffic in the low-
priority queue never gets sent. Strict priority queuing does not automatically adapt to changing network
requirements.
17.1.3 Weighted Round Robin Scheduling
Weighted round robin scheduling services queues based on the ratio determined by their queue weights (the
numbers you configure in the
High Weight or Low Weight field – see Figure 17-1 ). A queue with a larger weight
gets more service than a queue with a smaller weight. This queuing mechanism is highly efficient in that it divides
the available bandwidth across the different traffic queues. If one queue is empty, the switch just sends from the
other queue. See
section 17.3 for an example of weighted round robin scheduling.
17.2 Configuring Queuing
Click Queuing Method under Advanced Application in the navigation panel.