Least Load First; Example 1; Example 2; Figure 44 Least Load First Example - ZyXEL Communications ZyWall 35 User Manual

ZyWALL 35 User's Guide

7.4.1 Least Load First

The least load first algorithm uses the current (or recent) outbound and/or inbound bandwidth
utilization of each WAN interface as the load balancing index(es) when making decisions
about to which WAN interface a new LAN-originated session is to be distributed. The
outbound bandwidth utilization is defined as the measured outbound throughput over the
available outbound bandwidth and the inbound bandwidth utilization is defined as the
measured inbound throughput over the available inbound bandwidth.

7.4.1.1 Example 1

The following figure depicts an example where both the WAN ports on the ZyWALL are
connected to the Internet. The configured available outbound bandwidths for WAN 1 and
WAN 2 are 512K and 256K respectively.

Figure 44 Least Load First Example

If the outbound bandwidth utilization is used as the load balancing index and the measured
outbound throughput of WAN 1 is 412K and WAN 2 is 198K, the ZyWALL calculates the
load balancing index as shown in the table below.
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 36 Least Load First: Example 1

INTERFACE
WAN 1
WAN 2

7.4.1.2 Example 2

This example uses the same network scenario as in
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 102K, the ZyWALL
calculates the average load balancing indices as shown in the table below.
130
OUTBOUND
AVAILABLE (A)
512 K 412 K
256 K 198 K
LOAD BALANCING INDEX
MEASURED (M)
0.8
0.77
Figure 44 on page
(M/A )
130, but uses both the
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