ZyXEL Communications 5 Series User Manual

Chapter 9 WAN Screens

ZyWALL 5/35/70 Series User’s Guide

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.

This example uses the same network scenario as in 

, but uses both the 

outbound and inbound bandwidth utilization in calculating the load balancing index. If the 
measured inbound stream throughput for both WAN 1 and WAN 2 is 1600K, the ZyWALL 
calculates the average load balancing indices as shown in the table below. 

Since WAN 1 has a smaller load balancing index (meaning that it is less utilized than WAN 2), 
the ZyWALL will send the next new session traffic through WAN 1.

To configure Least Load First, select Least Load First in the Load Balancing Algorithm 
field.

Figure 100   Load Balancing: Least Load First

Table 36   Least Load First: Example 1

WAN 1

512 K

412 K

0.8

WAN 2

256 K 

198 K

0.77

Table 37   Least Load First: Example 2

WAN 1

512 K

412 K

8000 K 

1600 K

( 0.8 + 0.2) / 2 = 0.5

WAN 2

256 K 

198 K

2000 K 

1600 K

( 0.77 + 0.8 ) / 2 = 0.79