ZyXEL Communications Prestige 128 user manual Filter Configuration, About Filtering

￿￿￿Filter Configuration

About Filtering

The Prestige uses filters to decide whether or not to allow passage of a data packet and/or to make a call over the ISDN line. There are three types of filters involved: incoming data filters, outgoing data filters, and call filters. Data filters screen the data to determine if the packet should be allowed to pass. Call filters are used to determine if a call should be placed.

Outgoing packets must pass through the data filters before they encounter the call filters. Call filters are divided into two groups: default call filters and user-defined call filters. Prestige has default call filters that filter out administrative packets, e.g., RIP and SAP packets. The Prestige applies the default filters first and then the user-defined call filters if applicable as seen below:

Figure 10-1 Outgoing packet filtering Process

94 Filter Configuration