Queuing Commands - ZyXEL Communications XS3800-28 Cli Reference Manual

Use queuing commands to help solve performance degradation when there is network congestion.
Note: Queuing method configuration differs across Switch models.
• Some models allow you to select a queuing method on a port-by-port basis. For example, port 1 can
use Strictly Priority Queuing and ports 2-8 can use Weighted Round Robin.
• Other models allow you to specify one queuing method for all the ports at once.
71.1 Queuing Overview
The following queuing algorithms are supported by Zyxel Switches:
Note: Check your User's Guide for queuing algorithms supported by your model.
• Strictly Priority Queuing (SPQ) - 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.
Note: Switch models which have only 4 queues, support a limited version of SPQ. The highest
level queue is serviced using SPQ and the remaining queues use WRR queuing.
• Weighted Fair Queuing (WFQ)- guarantees each queue's minimum bandwidth based on its
bandwidth weight (portion) when there is traffic congestion. WFQ is activated only when a port has
more traffic than it can handle. Queues with larger weights get more guaranteed bandwidth than
queues with smaller weights. This queuing mechanism is highly efficient in that it divides any available
bandwidth across the different traffic queues. By default, the weight for Q0 is 1, for Q1 is 2, for Q2 is 3,
and so on. Guaranteed bandwidth is calculated as follows:
For example, using the default setting, Q0 on Port 1 gets a guaranteed bandwidth of:
• Weighted Round Robin Scheduling (WRR) - services queues on a rotating basis and is activated only
when a port has more traffic than it can handle. A queue is a given an amount of bandwidth based
on the queue weight value. 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.

Queuing Commands

Queue Weight x Port Speed
Total Queue Weight
1 x 100 Mbps = 3 Mbps
1+2+3+4+5+6+7+8
Ethernet Switch CLI Reference Guide
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