The Trunk Summary Screen - ZyXEL Communications USG40 User Manual

Chapter 10 Interfaces
turn. In addition, the WAN interfaces are assigned weights. An interface with a larger weight gets
more chances to transmit traffic than an interface with a smaller weight.
For example, in the figure below, the configured available bandwidth of WAN1 is 1M and WAN2 is
512K. You can set the ZyWALL/USG to distribute the network traffic between the two interfaces by
setting the weight of wan1 and wan2 to 2 and 1 respectively. The ZyWALL/USG assigns the traffic of
two sessions to wan1 and one session's traffic to wan2 in each round of 3 new sessions.
Figure 245 Weighted Round Robin Algorithm Example
Spillover
The spillover load balancing algorithm sends network traffic to the first interface in the trunk
member list until the interface's maximum allowable load is reached, then sends the excess
network traffic of new sessions to the next interface in the trunk member list. This continues as
long as there are more member interfaces and traffic to be sent through them.
Suppose the first trunk member interface uses an unlimited access Internet connection and the
second is billed by usage. Spillover load balancing only uses the second interface when the traffic
load exceeds the threshold on the first interface. This fully utilizes the bandwidth of the first
interface to reduce Internet usage fees and avoid overloading the interface.
In this example figure, the upper threshold of the first interface is set to 800K. The ZyWALL/USG
sends network traffic of new sessions that exceed this limit to the secondary WAN interface.
Figure 246 Spillover Algorithm Example

10.12 The Trunk Summary Screen

Click Configuration > Network > Interface > Trunk to open the Trunk screen. The Trunk
Summary screen lists the configured trunks and the load balancing algorithm that each is
configured to use.
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