ZyXEL Communications HS100/HS100W manual Chapter Filter Configuration, Introduction to Filters

HomeSafe User’s Guide

Chapter 27

Filter Configuration

This chapter shows you how to create and apply filters.

27.1 Introduction to Filters

Your HomeSafe uses filters to decide whether 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 the 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 LAN side. Call filtering is used to determine if a packet should be allowed to trigger a call. Remote node call filtering is only applicable when using PPPoE encapsulation. Outgoing packets must undergo data filtering before they encounter call filtering as shown in the following figure.

Outgoing

Packet

Data

Filtering

Match

Drop

packet

No

match

Call Filtering

	No		No	Active Data
Built-in		User-defined
default	match	Call Filters	match		Initiate call
					if line not up
Call Filters		(if applicable)
						Send packet
							and reset
Match		Match				Idle Timer

Drop packet				Drop packet
if line not up				if line not up
	Or				Or
			Send packet				Send packet
		but do not reset				but do not reset
			Idle Timer				Idle Timer

Figure 27-1 Outgoing Packet Filtering Process

For incoming packets, your HomeSafe applies data filters only. Packets are processed depending upon whether a match is found. The following sections describe how to configure filter sets.

27.1.1 The Filter Structure of the HomeSafe

A filter set consists of one or more filter rules. Usually, you would group related rules, e.g., all the rules for NetBIOS, into a single set and give it a descriptive name. The HomeSafe allows you to configure up to twelve filter sets with six rules in each set, for a total of 72 filter rules in the system. You cannot mix device filter rules and protocol filter rules within the same set. You can

Filter Configuration 27-1