Anti-Ip Address Spoofing; Dhcp Snooping Configuration - ZyXEL Communications MSC1024G Series User Manual

You can also specify static IP addresses (for a subscriber given a static IP address) on a
subscriber port. This is useful when service providers assign static WAN IP addresses to some
subscribers. This static binding allows the switch to forward frames with the specified IP
addresses.
In the following network example, the DHCP snooping table on the switch contains two
source IP addresses: 192.168.1.100 (DHCP-assigned) and 192.168.1.200 (static). Traffic from
computers A and B is allowed to go through the DSL ports. While traffic from computer C is
blocked since its IP address is unknown to the switch (not in the DHCP snooping table).
Figure 43 DHCP Snooping Network Example
A: 192.168.1.100
B: 192.168.1.200
C: 192.168.1.10

5.3.1 Anti-IP Address Spoofing

While performing DHCP snooping, a line card records which IP address is assigned to each
DHCP client MAC address. and which VLAN the client uses. The line card drops packets
from a device using an IP address that is assigned to a different MAC address.

5.4 DHCP Snooping Configuration

Click ACL > DHCP Snoop to display the screen shown next.
MSC1000G/1024G/1224G Series User's Guide
Chapter 5 Access Control List Screens
DHCP Snooping
192.168.1.100
192.168.1.200
DHCP
Internet
99