ZyXEL Communications Internet Security Appliance ZyWALL5UTM 4.0 - Manual (Page 401)

ZyWALL 5/35/70 Series User’s Guide
401 Chapter 25 Bandwidth Management
When you enable maximize bandwidth usage, the ZyWALL first makes sure that each
bandwidth class gets up to its bandwidth allotment. Next, the ZyWALL 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 ZyWALL gives extra bandwidth to
that class.
When multiple classes require more bandwidth, the ZyWALL 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
ZyWALL distributes the available bandwidth equally among classes with the same priority
level.
25.7.4 Reserving Bandwidth for Non-Bandwidth Class Traffic
Do the following three steps to configure the ZyWALL 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 sub-classes that have the root class as their
parent (see Section 25.8 on page 403 ).
25.7.5 Maximize Bandwidth Usage Example
Here is an example of a ZyWALL 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 137 Maximize Bandwidth Usage Example
BANDWIDTH CLASSES AND ALLOTMENTS
Root Class: 10240 kbps Administration: 2048 kbps
Sales: 2048 kbps
Marketing: 2048 kbps
Research: 2048 kbps
The ZyWALL divides up the unbudgeted 2048 kbps among the classes that require more
bandwidth. If the administration department only uses 1024 kbps of the budgeted 2048 kbps,
the ZyWALL also divides the remaining 1024 kbps among the classes that require more
bandwidth. Therefore, the ZyWALL divides a total of 3072 kbps of unbudgeted and unused
bandwidth among the classes that require more bandwidth.