ZyXEL ZyWALL USG 2000 User Guide - Page 340

Chapter 14 Trunks Since WAN 2 has a smaller load balancing index (meaning that it is less utilized than WAN 1), the ZyWALL will send the subsequent new session traffic through WAN 2. Table 78 Least Load First Example INTERFACE OUTBOUND AVAILABLE (A) MEASURED (M) WAN 1 512 K 412 K WAN 2 256 K 198 K LOAD BALANCING INDEX (M/A) 0.8 0.77 Weighted Round Robin The Weighted Round Robin (WRR) algorithm is best suited for situations when the bandwidths set for the two WAN interfaces are different. Similar to the Round Robin (RR) algorithm (see Section 14.4 on page 345), the Weighted Round Robin (WRR) algorithm sets the ZyWALL to send traffic through each WAN interface in turn. In addition, the WAN interfaces are assigned weights. An interface with a larger weight gets more of the traffic than an interface with a smaller weight. For example, in the figure below, the configured available bandwidth of ge2 is 1M and ge3 is 512K. You can set the ZyWALL to distribute the network traffic between the two interfaces by setting the weight of ge2 and ge3 to 2 and 1 respectively. The ZyWALL assigns the traffic of two sessions to ge2 for every session's traffic assigned to ge3. Figure 268 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 340 ZyWALL USG 2000 User's Guide