Chapter 8 WAN Screens

This algorithm is best suited for situations when the bandwidths set for the two WAN interfaces are different.

For example, in the figure below, the configured available bandwidth of WAN1 is 1M and WAN2 is 512K. You can set the ZyWALL to distribute the network traffic between the two interfaces by setting the weight of WAN1 and WAN2 to 2 and 1 respectively. The ZyWALL assigns the traffic of two sessions to WAN1 for every one session's traffic assigned to WAN2.

Figure 105 Weighted Round Robin Algorithm Example

8.4.3 Spillover

With the spillover load balancing algorithm, the ZyWALL sends network traffic to the primary interface until the maximum allowable load is reached, then the ZyWALL sends the excess network traffic of new sessions to the secondary WAN interface. Configure the Route Priority metrics in the WAN General screen to determine the primary and secondary WANs.

In cases where the primary WAN interface uses an unlimited access Internet connection and the secondary WAN uses a per-use timed access plan, the ZyWALL will only use the secondary WAN interface when the traffic load reaches the upper threshold on the primary WAN interface. This allows you to fully utilize the bandwidth of the primary WAN interface while avoiding overloading it and reducing Internet connection fees at the same time.

In the following example figure, the upper threshold of the primary WAN interface is set to 800K. The ZyWALL sends network traffic of a new session that exceeds this limit to the secondary WAN interface.

Figure 106 Spillover Algorithm Example

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ZyWALL 2WG User’s Guide