User's Manual

Chapter 13 Trunks
ISG50 User’s Guide
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the weight of wan1 and wan2 to 2 and 1 respectively. The ISG50 assigns the traffic of two sessions
to wan1 for every session's traffic assigned to wan2.
Figure 190 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 ISG50 sends
network traffic of new sessions that exceed this limit to the secondary WAN interface.
Figure 191 Spillover Algorithm Example
Finding Out More
•See Section 6.6.4 on page 98 for related information on the Trunk screens.
•See Section 7.3 on page 111 for an example of how to configure load balancing.
•See Section 13.4 on page 288 for more background information on trunks.
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