ZyXEL Communications 1000 User Manual

ZyWALL USG 1000 User’s Guide

Use trunks for WAN traffic load balancing to increase overall network throughput 
and reliability. Load balancing divides traffic loads between multiple interfaces. 
This allows you to improve quality of service and maximize bandwidth utilization 
for multiple ISP links. 

Maybe you have two Internet connections with different bandwidths. You could set 
up a trunk that uses spillover or weighted round robin load balancing so time-
sensitive traffic (like video) usually goes through the higher-bandwidth interface. 
For other traffic, you might want to use least load first load balancing to even out 
the distribution of the traffic load.

Suppose ISP A has better connections to Europe while ISP B has better 
connections to Australia. You could use policy routes and trunks to have traffic for 
your European branch office primarily use ISP A and traffic for your Australian 
branch office primarily use ISP B. 

Or maybe one of the ZyWALL's interfaces is connected to an ISP that is also your 
Voice over IP (VoIP) service provider. You can use policy routing to send the VoIP 
traffic through a trunk with the interface connected to the VoIP service provider 
set to active and another interface (connected to another ISP) set to passive. This 
way VoIP traffic goes through the interface connected to the VoIP service provider 
whenever the interface’s connection is up.

• Use  the  Trunk summary screen (

) to configure link 

sticking and view the list of configured trunks and which load balancing 

algorithm each trunk uses.

• Use  the  Trunk Edit screen (

) to configure which 

interfaces belong to each trunk and the load balancing algorithm each trunk 

uses.