Bay Technical Associates RM356 - Manual (Page 77)

Filter Configuration 8-1
Chapter 8
Filter Configuration
This chapter provides information about using filters and configuring filters for your
Model RM356 Modem Router.
The router uses filters to decide whether to allow passage of a data packet and/or to make a call
over the phone line. Three types of filters are involved: incoming data filters, outgoing data filters,
and call filters. Data filters screen the data to determine if the packet should be allowed to pass.
Call filters are used to determine if a call should be placed.
Outgoing packets must pass through the data filters before they encounter call filters. The call
filters are divided into two groups: default call filters and user-defined call filters. The Model
RM356 Modem Router has default call filters that filter out administrative packets (for example,
RIP packets). The router applies the default filters first and then, if applicable, applies the
user-defined call filters as shown in
Figure 8-1 .
Figure 8-1. Outgoing Packet Filtering Process
7787EA
Outgoing
packet
Data
filters
Initiate call
if line not up
Send packet
and reset
idle timer
Send packet
but do not
reset idle timer
Active data
Drop packet
if line not up
Or
No
match
Match Match
Send packet
but do not
reset idle timer
Drop packet
if line not up
Or
Match
No
match
No
match
Call filters
Drop
packet
Built-in
default call
filters
User-defined
call filters
(if applicable)