ZyWALL 5/35/70 Series User’s Guide

Figure 49 Spillover Algorithm Example

7.5 TCP/IP Priority (Metric)

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".

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

2The priorities of the WAN port routes must always be higher than the dial-backup and traffic redirect route priorities.

Take a ZyWALL with multiple WAN ports as an example, lets say that you have the WAN operation mode set to active/passive and the WAN 1 route has a metric of "2", the WAN 2 route has a metric of "3", the traffic-redirect route has a metric of "14" and the dial-backup route has a metric of "15". In this case, the WAN 1 route acts as the primary default route. If the WAN 1 route fails to connect to the Internet, the ZyWALL tries the WAN 2 route next. If the WAN 2 route fails, the ZyWALL tries the traffic-redirect route. In the same manner, the ZyWALL uses the dial-backup route if the traffic-redirect route also fails.

For a ZyWALL with a single WAN port, if the WAN port route has a metric of "1" and the traffic-redirect route has a metric of "2" and dial-backup route has a metric of "3", then the WAN port route acts as the primary default route. If the WAN port route fails to connect to the Internet, the ZyWALL tries the traffic-redirect route next. In the same manner, the ZyWALL uses the dial-backup route if the traffic-redirect route also fails.

The dial-backup or traffic redirect routes cannot take priority over the WAN (or WAN 1 and WAN 2) routes.

7.6 WAN General

Click NETWORK, WAN to open the General screen. Use this screen to configure load balancing, route priority and traffic redirect properties.

Chapter 7 WAN Screens

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