ZyXEL Communications ZyXEL ZyWALL 5, User Manual

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ZyWALL 5 User’s Guide
Chapter 19 Bandwidth Management 303
19.7 Scheduler
The scheduler divides up an interface’s bandwidth among the bandwidth classes. The
ZyWALL has two types of scheduler: fairness-based and priority-based.
19.7.1 Priority-based Scheduler
With the priority-based scheduler, the ZyWALL forwards traffic from bandwidth classes
according to the priorities that you assign to the bandwidth classes. The larger a bandwidth
class’s priority number is, the higher the priority. Assign real-time applications (like those
using audio or video) a higher priority number to provide smoother operation.
19.7.2 Fairness-based Scheduler
The ZyWALL 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.
19.8 Maximize Bandwidth Usage
The maximize bandwidth usage option ( Figure 150 on page 307 ) allows the ZyWALL 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 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.
FTP 64 Kbps 64 Kbps
E-mail 64 Kbps 64 Kbps
Video 64 Kbps 64 Kbps
Table 101 Application and Subnet-based Bandwidth Management Example (continued)
TRAFFIC TYPE FROM SUBNET A FROM SUBNET B