ZyWALL 5/35/70 Series User’s Guide

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.

1Leave some of the interface’s bandwidth unbudgeted.

2Do not enable the interface’s Maximize Bandwidth Usage option.

3Do not enable bandwidth borrowing on the sub-classes that have the root class as their parent (see Section 25.8 on page 403).

25.7.5Maximize 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.

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Chapter 25 Bandwidth Management