ZyXEL Communications 5 Series User Manual

 Chapter 9 WAN Screens

ZyWALL 5/35/70 Series User’s Guide

You can use policy routing to specify the WAN interface that specific services go through. An 
ISP may give traffic from certain (more expensive) connections priority over the traffic from 
other accounts. You could route delay intolerant traffic (like voice over IP calls) through this 
kind of connection. Other traffic could be routed through a cheaper broadband Internet 
connection that does not provide priority service. If one WAN interface's connection goes 
down, the ZyWALL can automatically send its traffic through the other WAN interface. See 

 for details.

The ZyWALL's NAT feature allows you to configure sets of rules for one WAN interface and 
separate sets of rules for the other WAN interface. Refer to 

You can select through which WAN interface you want to send out traffic from UPnP-enabled 
applications (see 

). 

The ZyWALL's DDNS lets you select which WAN interface you want to use for each 
individual domain name. The DDNS high availability feature lets you have the ZyWALL use 
the other WAN interface for a domain name if the configured WAN interface's connection 
goes down. See 

 for details.

When configuring a VPN rule, you have the option of selecting one of the ZyWALL's domain 
names in the My Address field.

On the ZyWALL, load balancing is the process of dividing traffic loads between the two 
WAN interfaces (or ports). This allows you to improve quality of services and maximize 
bandwidth utilization. 

See also policy routing to provide quality of service by dedicating a route for a specific traffic 
type and bandwidth management to specify a set amount of bandwidth for a specific traffic 
type on an interface.

The ZyWALL uses three load balancing methods (least load first, weighted round robin and 
spillover) to decide which WAN interface the traffic for a session

1

 (from the LAN) uses. 

The available bandwidth you configure on the ZyWALL refers to the actual bandwidth 
provided by the ISP and the measured bandwidth refers to the bandwidth an interface is 
currently using.

The metric represents the "cost of transmission". A router determines the best route for 
transmission by choosing a path with the lowest "cost". RIP routing uses hop count as the 
measurement of cost, with a minimum of "1" for directly connected networks. The number 
must be between "1" and "15"; a number greater than "15" means the link is down. The 
smaller the number, the lower the "cost".

1 The metric sets the priority for the ZyWALL's routes to the Internet. Each route must 

have a unique metric.

2 The priorities of the WAN interface routes must always be higher than the dial-backup 

and traffic redirect route priorities.

1.

In the load balancing section, a session may refer to normal connection-oriented, UDP and SNMP2 traffic.