Chapter 12 Policy and Static Routes

 

Table 92 Network > Routing > Static Route > Edit (continued)

 

LABEL

DESCRIPTION

 

Gateway IP

Select the radio button and enter the IP address of the next-hop gateway. The

 

 

gateway is a router or switch on the same segment as your ZyWALL's interface(s).

 

 

The gateway helps forward packets to their destinations.

 

 

 

 

Interface

Select the radio button and a predefined interface through which the traffic is sent.

 

 

 

 

Metric

Metric represents the “cost” of transmission for routing purposes. IP routing uses

 

 

hop count as the measurement of cost, with a minimum of 1 for directly connected

 

 

networks. Enter a number that approximates the cost for this link. The number need

 

 

not be precise, but it must be between 1 and 15. In practice, 2 or 3 is usually a good

 

 

number.

 

 

 

 

OK

Click OK to save your changes back to the ZyWALL.

 

 

 

 

Cancel

Click Cancel to exit this screen without saving.

 

 

 

12.4 Policy Routing Technical Reference

Here is more detailed information about some of the features you can configure in policy routing.

NAT and SNAT

NAT (Network Address Translation - NAT, RFC 1631) is the translation of the IP address in a packet in one network to a different IP address in another network. Use SNAT (Source NAT) to change the source IP address in one network to a different IP address in another network.

Port Triggering

Some services use a dedicated range of ports on the client side and a dedicated range of ports on the server side. With regular port forwarding, you set the port(s) and IP address to forward a service (coming in from the remote server) to a client computer. The problem is that port forwarding only forwards a service to a single IP address. In order to use the same service on a different computer, you have to manually replace the client computer's IP address with another client computer's IP address.

Port triggering allows the client computer to take turns using a service dynamically. Whenever a client computer’s packets match the routing policy, it can use the pre-defined port triggering setting to connect to the remote server without manually configuring a port forwarding rule for each client computer.

Port triggering is used especially when the remote server responses using a different port from the port the client computer used to request a service. The ZyWALL records the IP address of a client computer that sends traffic to a remote server to request a service (incoming service). When the ZyWALL receives a new connection (trigger service) from the remote server, the ZyWALL forwards the traffic to the IP address of the client computer that sent the request.

In the following example, you configure two services for port triggering:

 

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ZyWALL USG 100/200 Series User’s Guide