Chapter 23 Filter Configuration; About Filtering; Figure 23-1 Outgoing Packet Filtering Process - ZyXEL Communications Prestige 861H-G1 User Manual

23.1 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
Data
Packet
Match
Drop
packet
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.
Filter Configuration
This chapter shows you how to create and apply filters.
No
Built-in
match
default
Call Filters
Match
Drop packet
if line not up
Or

Figure 23-1 Outgoing Packet Filtering Process

Prestige 861H User's Guide
Filter Configuration
Call Filtering
No
match
No
User-defined
match
Call Filters
(if applicable)
Match
Drop packet
if line not up
Or
Send packet Send packet
but do not reset but do not reset
Idle Timer Idle Timer
Chapter 23
Active Data
Initiate call
if line not up
Send packet
and reset
Idle Timer
23-1