ZyXEL Communications Prestige 653HWI series, User Manual

Page: 247 / 564

Prestige 653HWI Series User’s Guide
Bandwidth Management 21-5
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.
21.6.1 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.
Leave some of the interface’s bandwidth unbudgeted.
Do not enable the interface’s
Maximize Bandwidth Usage option.
Do not enable bandwidth borrowing on the child-classes that have the root class as their parent (see section
21.7 ).
21.6.2 Maximize Bandwidth Usage Example
Here is an example of a Prestige that has maximized bandwidth usage enabled on an interface. The first
figure shows each bandwidth class’s bandwidth budget and priority. The classes are set up based on subnets.
The interface is set to 10 Mbps. Each subnet is allocated 2 Mbps. The unbudgeted 2 Mbps allows traffic not
defined in one of the bandwidth filters to go out when you do not select the maximize bandwidth option.