ZyXEL Communications Prestige 662HW Series, User Manual

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Prestige 662HW Series User’s Guide
Filter Configuration 33-1
Chapter 33
Filter Configuration
This chapter shows you how to create and apply filters.
33.1 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.
Figure 33-1 Outgoing Packet Filtering Process
Two sets of factory filter rules have been configured in menu 21 to prevent NetBIOS traffic from
triggering calls. A summary of their filter rules is shown in the figures that follow.
The following figure illustrates the logic flow when executing a filter rule.
Data
Outgoing
Packet
Drop
packet
Built-in
default
Call Filters
User-defined
Call Filters
(if applicable)
Initiate call
if line not up
Active Data
Send packet
and reset
Idle Timer
Or Or
Drop packet
if line not up Drop packet
if line not up
Send packet
but do not reset
Idle Timer
Send packet
but do not reset
Idle Timer
Match Match Match
No
match
No
match
No
match
Call Filtering