ZyXEL Communications Prestige 661H Series, User Manual

Page: 231 / 547

Prestige 661H/HW Series User’s Guide
231 Chapter 19 Media Bandwidth Management Advanced Setup
19.5 Scheduler
The scheduler divides up an interface’s bandwidth among the bandwidth classes. The Prestige
has two types of scheduler: fairness-based and priority-based.
19.5.1 Priority-based Scheduler
With the priority-based scheduler, the Prestige forwards traffic from bandwidth classes
according to the priorities that you assign to the bandwidth classes. The larger a bandwidth
class’s priority number is, the higher the priority. Assign real-time applications (like those
using audio or video) a higher priority number to provide smoother operation.
19.5.2 Fairness-based Scheduler
The Prestige divides bandwidth equally among bandwidth classes when using the fairness-
based scheduler; thus preventing one bandwidth class from using all of the interface’s
bandwidth.
19.6 Maximize Bandwidth Usage
The maximize bandwidth usage option (see Section 19.7.1 on page 233 ) allows the Prestige to
divide up any available bandwidth on the interface (including unallocated bandwidth and any
allocated bandwidth that a class is not using) among the bandwidth classes that require more
bandwidth.
When you enable maximize bandwidth usage, the Prestige first makes sure that each
bandwidth class gets up to its bandwidth allotment. Next, the Prestige divides up an interface’s
available bandwidth (bandwidth that is unbudgeted or unused by the classes) depending on
how many bandwidth classes require more bandwidth and on their priority levels. When only
one class requires more bandwidth, the Prestige gives extra bandwidth to that class.
When multiple classes require more bandwidth, the Prestige gives the highest priority classes
the available bandwidth first (as much as they require, if there is enough available bandwidth),
and then to lower priority classes if there is still bandwidth available. The Prestige distributes
the available bandwidth equally among classes with the same priority level.
19.6.1 Reserving Bandwidth for Non-Bandwidth Class Traffic
Do the following three steps to configure the Prestige to allow bandwidth for traffic that is not
defined in a bandwidth filter.
1 Leave some of the interface’s bandwidth unbudgeted.
2
Do not enable the interface’s Maximize Bandwidth Usage option.
3 Do not enable bandwidth borrowing on the child-classes that have the root class as their
parent (see
Section 19.7 on page 233 ).