ZyXEL Communications 5 Series User Manual

 Chapter 9 WAN Screens

ZyWALL 5/35/70 Series User’s Guide

The following table describes the related fields in this screen.

Round Robin routes traffic on a rotating basis and is activated only when a WAN interface has 
more traffic than the configured available bandwidth. On the ZyWALL with two WAN 
interfaces, an amount of traffic is sent through the first interface. The second interface is also 
given an equal amount of traffic, and then the same amount of traffic is sent through the first 
interface again; and so on. This works in a looping fashion until there is no outgoing traffic.

Similar to the Round Robin (RR) algorithm, 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. 

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.

Table 38   Load Balancing: Least Load First

Active/Active 
Mode

Select Active/Active Mode and set the related fields to enable load balancing on 
the ZyWALL. 

Load Balancing 
Algorithm

Set the load balancing method to Least Load First.

WAN Interface 
to Local Host 
Mapping 
Timeout 

Select this option to have the ZyWALL send all of a local computer’s traffic through 
the same WAN interface for the period of time that you specify (1 to 600 seconds). 
This is useful when a redirect server forwards a local user’s request for a file and 
informs the file server that a particular WAN IP address is requesting the file. If the 
user’s subsequent sessions came from a different WAN IP address, the file server 
would deny the request. 

Time Frame

You can set the ZyWALL to get the measured bandwidth using the average 
bandwidth in the specified time interval. 
Enter the time interval between 10 and 600 seconds. 

Load Balancing 
Index(es)

Specify the direction of the traffic utilization you want the ZyWALL to use in 
calculating the load balancing index. 
Select Outbound Only, Inbound Only or Outbound + Inbound.

Interface

This field displays the name of the WAN interface (WAN 1 and WAN 2). 

Available 
Inbound 
Bandwidth 

This field is applicable when you select Outbound + Inbound or Inbound Only in 
the Load Balancing Index(es) field. 
Specify the inbound (or downstream) bandwidth (in kilo bites per second) for the 
interface. This should be the actual downstream bandwidth that your ISP provides. 

Available 
Outbound 
Bandwidth

This field is applicable when you select Outbound + Inbound or Outbound Only in 
the Load Balancing Index(es) field. 
Specify the outbound (or upstream) bandwidth (in kilo bites per second) for the 
interface. This should be the actual upstream bandwidth that your ISP provides.