ZyXEL Communications Prestige 28641 - Manual (Page 109)

Filter Configuration 95
10
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