ZyXEL Communications Prestige 623ME-T, User Manual

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Prestige 623ME-T User’s Guide
Filter Configuration 18-1
Chapter 18
Filter Configuration
This chapter shows you how to create and apply filters.
18.1 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.