ADSL Router User's Reference Guide

11-26 User’s Reference Guide
Example 2
Incoming packet has the source address of 200.1.1.184.
This incoming IP packet (10000000) has a source IP address that does not match the network address in the
Source IP Address field (00000000) in the Netopia 4541/4542. This rule will forward this packet because the
packet does not match.
Example 3
Incoming packet has the source address of 200.1.1.184.
Since the Source IP Network Address in the Netopia 4541/4542 is 01100000, and the source IP address after
the logical AND is 1011000, this rule does not match and this packet will be forwarded.
Filter Rule: 200.1.1.0 (Source IP Network Address)
255.255.255.128 (Source IP Mask)
Forward = No (What happens on match)
IP Address Binary Representation
200.1.1.184 10111000 (Source address in incoming IP packet)
AND
255.255.255.128 10000000 (Perform the logical AND)
10000000 (Logical AND result)
Filter Rule: 200.1.1.96 (Source IP Network Address)
255.255.255.240 (Source IP Mask)
Forward = No (What happens on match)
IP Address Binary Representation
200.1.1.184 10111000 (Source address in incoming IP packet)
AND
255.255.255.240 11110000 (Perform the logical AND)
10110000 (Logical AND result)