ZyXEL Communications P-660HW-D Series User Manual

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P-660HW-D Series User’s Guide
Chapter 13 Bandwidth Management
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13.5.1  Priority-based Scheduler
With the priority-based scheduler, the ZyXEL device 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.
13.5.2  Fairness-based Scheduler
The ZyXEL device 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. 
13.6  Maximize Bandwidth Usage
The maximize bandwidth usage option (see 
) allows the ZyXEL device 
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 ZyXEL device first makes sure that each 
bandwidth class gets up to its bandwidth allotment. Next, the ZyXEL device 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 ZyXEL device gives extra 
bandwidth to that class. 
When multiple classes require more bandwidth, the ZyXEL device 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 ZyXEL 
device distributes the available bandwidth equally among classes with the same priority level. 
13.6.1  Reserving Bandwidth for Non-Bandwidth Class Traffic
Do the following three steps to configure the ZyXEL device 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