What You Need To Know - ZyXEL Communications USG40 User Manual

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/USG'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
and which load balancing algorithm each trunk uses.
• Use the Add Trunk screen
a trunk and the load balancing algorithm the trunk uses.
• Use the Add System Default screen
balancing algorithm for the system default trunk.

10.11.1 What You Need to Know

• Add WAN interfaces to trunks to have multiple connections share the traffic load.
• If one WAN interface's connection goes down, the ZyWALL/USG sends traffic through another
member of the trunk.
• For example, you connect one WAN interface to one ISP and connect a second WAN interface to
a second ISP. The ZyWALL/USG balances the WAN traffic load between the connections. If one
interface's connection goes down, the ZyWALL/USG can automatically send its traffic through
another interface.
You can also use trunks with policy routing to send specific traffic types through the best WAN
interface for that type of traffic.
• If that interface's connection goes down, the ZyWALL/USG can still send its traffic through
another interface.
• You can define multiple trunks for the same physical interfaces.
LAN user A logs into server B on the Internet. The ZyWALL/USG uses wan1 to send the request to
1
server B.
The ZyWALL/USG is using active/active load balancing. So when LAN user A tries to access
2
something on the server, the request goes out through wan2.
The server finds that the request comes from wan2's IP address instead of wan1's IP address and
3
rejects the request.
If link sticking had been configured, the ZyWALL/USG would have still used wan1 to send LAN user
A's request to the server and server would have given the user A access.
Chapter 10 Interfaces
(Section 10.12 on page
(Section 10.12.1 on page
(Section 10.12.2 on page
ZyWALL/USG Series User's Guide
347
349) to view the list of configured trunks
351) to configure the member interfaces for
353) to configure the load