Chapter 16 Filter Configuration; About Filtering; Figure 16-1 Outgoing Packet Filtering Process - ZyXEL Communications Prestige 652 User Manual

16.1 About Filtering

Your Prestige uses filters to decide whether or not to allow passage of a data packet and/or to make a call.
There are two types of filter applications: data filtering and call filtering. Filters are subdivided into device
and protocol filters, which are discussed later.
Data filtering screens data to determine if the packet should be allowed to pass. Data filters are divided into
incoming and outgoing filters, depending on the direction of the packet relative to a port. Data filtering can
be applied on either the WAN side or the Ethernet side. Call filtering is used to determine if a packet should
be allowed to trigger a call.
Outgoing packets must undergo data filtering before they encounter call filtering. Call filters are divided
into two groups, the built-in call filters and user-defined call filters. Your Prestige has built-in call filters
that prevent administrative, for example, RIP packets from triggering calls. These filters are always enabled
and not accessible to you. Your Prestige applies the built-in filters first and then the user-defined call filters,
if applicable, as shown next.
Outgoing
Packet
Filter Configuration
No
match
Data
Call Filters
Filtering
Match
Drop Drop packet
packet if line not up

Figure 16-1 Outgoing Packet Filtering Process

Filter Configuration
This chapter shows you how to create and apply filters.
Call Filtering
No
match
Built-in
User-defined
default
Call Filters
(if applicable)
Match
Drop packet
if line not up
Or
Send packet
but do not reset
Idle Timer
Prestige 652 ADSL Security Router
Chapter 16
Active Data
No
match
Initiate call
if line not up
Match
Or
Send packet
but do not reset
Idle Timer
Send packet
and reset
Idle Timer
16-1