ZyXEL Communications P-661H Series User Manual

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 Chapter 14 Bandwidth Management
P-661H/HW Series User’s Guide
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14.5.2  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. 
14.6  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. 
14.6.1  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 
parent (see 
).
14.6.2  Maximize Bandwidth Usage Example
Here is an example of a ZyXEL Device that has maximize bandwidth usage enabled on an 
interface. The following table shows each bandwidth class’s bandwidth budget. The classes 
are set up based on subnets. The interface is set to 10240 kbps. Each subnet is allocated 2048 
kbps. The unbudgeted 2048 kbps allows traffic not defined in any of the bandwidth filters to 
go out when you do not select the maximize bandwidth option.
Table 88   Maximize Bandwidth Usage Example
BANDWIDTH CLASSES AND ALLOTMENTS
Root Class: 10240 kbps
Administration: 2048 kbps
Sales: 2048 kbps
Marketing: 2048 kbps
Research: 2048 kbps