Figure 17-4 Bandwidth Allotment Example - ZyXEL Communications ZyWALL 5 User Manual

ZyWALL 5 Internet Security Appliance
17.6.1 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.
Leave some of the interface's bandwidth unbudgeted.
1.
Do not enable the interface's Maximize Bandwidth Usage option.
2.
Do not enable bandwidth borrowing on the sub-classes that have the root class as their parent (see
3.
section 17.7).
17.6.2 Maximize Bandwidth Usage Example
Here is an example of a ZyWALL that has maximize bandwidth usage enabled on an interface. The
first figure shows each bandwidth class's bandwidth budget and priority. The classes are set up based
on subnets. The interface is set to 10 Mbps. Each subnet is allocated 2 Mbps. The unbudgeted 2 Mbps
allows traffic not defined in one of the bandwidth filters to go out when you do not select the
maximize bandwidth option.
The following figure shows the bandwidth usage with the maximize bandwidth usage option enabled.
The ZyWALL divides up the unbudgeted 2 Mbps among the classes that require more bandwidth. If
the administration department only uses 1 Mbps of the budgeted 2 Mbps, the ZyWALL also divides
the remaining 1 Mbps among the classes that require more bandwidth. Therefore, the ZyWALL
divides a total of 3 Mbps total of unbudgeted and unused bandwidth among the classes that require
more bandwidth.
In this case, suppose that all of the classes except for the administration class need more bandwidth.
Each class gets up to its budgeted bandwidth. The administration class only uses 1 Mbps of its
budgeted 2 Mbps.
Sales and Marketing are first to get extra bandwidth because they have the highest priority (6).
If they each require 1.5 Mbps or more of extra bandwidth, the ZyWALL divides the total 3
Mbps total of unbudgeted and unused bandwidth equally between the sales and marketing
departments (1.5 Mbps extra to each for a total of 3.5 Mbps for each) because they both have
the highest priority level.
17-4

Figure 17-4 Bandwidth Allotment Example

Bandwidth Management