User`s guide
Chapter 5 WAN & 3G Cellular Screens
LAN-Cell 2 User’s Guide
97
5.2.1 Configuring Load Balancing
To configure load balancing on the LAN-Cell, click NETWORK > WAN in the navigation
panel. The WAN General screen displays by default. Select Active/Active Mode under
Operation Mode to enable load balancing on the LAN-Cell.
The WAN General screen varies depending on what you select in the Load Balancing
Algorithm field.
5.2.1.1 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 criteria for making decisions on how
how to route traffic. The outbound bandwidth utilization is defined as the measured outbound
throughput over the available outbound bandwidth. The inbound bandwidth utilization is
defined as the measured inbound throughput over the available inbound bandwidth. The two
ratios are indexes used to calculate which WAN interface is less utilized at the time. A new
LAN-originated session is distributed to the less utilized WAN interface.
5.2.1.2 Example 1
The following figure depicts an example where both the WAN interfaces on the LAN-Cell are
connected to the Internet. The configured available outbound bandwidths for WAN and
Cellular are 512K and 256K respectively.
Figure 49 Least Load First Example
If the outbound bandwidth utilization is used as the load balancing index and the measured
outbound throughput of WAN is 412K and Cellular is 198K, the LAN-Cell calculates the load
balancing index as shown in the table below.
Since Cellular has a smaller load balancing index (meaning that it is less utilized than WAN),
the LAN-Cell will send the subsequent new session traffic through Cellular.
5.2.1.3 Example 2
This example uses the same network scenario as in Figure 49 on page 97, but uses both the
outbound and inbound bandwidth utilization in calculating the load balancing index. If the
measured inbound stream throughput for both WAN and Cellular is 1600K, the LAN-Cell
calculates the average load balancing indices as shown in the table below.
Table 20 Least Load First: Example 1
INTERFACE
OUTBOUND
LOAD BALANCING INDEX
(M/A)
AVAILABLE (A) MEASURED (M)
WAN 512 K 412 K 0.8
Cellular 256 K 198 K 0.77