ZyXEL Communications ZyWall USG20-VPN User Manual page 404

Maximize Bandwidth Usage
Maximize bandwidth usage allows applications with maximize bandwidth usage enabled to "borrow"
any unused bandwidth on the out-going interface.
After each application gets its configured bandwidth rate, the USG uses the fairness- based
scheduler to divide any unused bandwidth on the out-going interface amongst applications that
need more bandwidth and have maximize bandwidth usage enabled.
Unused bandwidth is divided equally. Higher priority traffic does not get a larger portion of the
unused bandwidth.
Bandwidth Management Behavior
The following sections show how bandwidth management behaves with various settings. For
example, you configure DMZ to WAN policies for FTP servers A and B. Each server tries to send
1000 kbps, but the WAN is set to a maximum outgoing speed of 1000 kbps. You configure policy A
for server A's traffic and policy B for server B's traffic.
Figure 281 Bandwidth Management Behavior
1000 kbps
1000 kbps
Configured Rate Effect
In the following table the configured rates total less than the available bandwidth and maximize
bandwidth usage is disabled, both servers get their configured rate.
Table 151 Configured Rate Effect
POLICY CONFIGURED RATE
A 300 kbps
B 200 kbps
Priority Effect
Here the configured rates total more than the available bandwidth. Because server A has higher
priority, it gets up to it's configured rate (800 kbps), leaving only 200 kbps for server B.
Table 152 Priority Effect
POLICY CONFIGURED RATE
A 800 kbps
B 1000 kbps
Chapter 26 BWM (Bandwidth Management)
BWM
1000 kbps
MAX. B. U.
No
No
MAX. B. U.
Yes
Yes
USG20(W)-VPN Series User's Guide
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PRIORITY ACTUAL RATE
1 300 kbps
1 200 kbps
PRIORITY ACTUAL RATE
1 800 kbps
2 200 kbps