ZyXEL Communications P-660H-Tx v2 - Manual (Page 157)

Chapter 12 Bandwidth Management
P-660H-Tx v2 User’s Guide
157
12.5.2 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.
12.6 Maximize Bandwidth Usage
The maximize bandwidth usage option (see Figure 82 on page 160 ) 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.
12.6.1 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.
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 12.9 on page 160 ).
12.6.2 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 52 Maximize Bandwidth Usage Example
BANDWIDTH CLASSES AND ALLOTMENTS
Root Class: 10240 kbps Administration: 2048 kbps
Sales: 2048 kbps
Marketing: 2048 kbps
Research: 2048 kbps