ZyXEL Communications ADSL2+ Ethernet/USB Gateway 660RU-Tx Series, User Manual

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Prestige 660RU-Tx Series User’s Guide
Chapter 22 Filter Configuration 178
C
H A P T E R
22
Filter Configuration
This chapter shows you how to create and apply filters.
22.1 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 116 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
Filtering
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