ZyXEL Communications XGS-4526 사용자 설명서

XGS-4526/4528F/4728F User’s Guide

Use IP source guard to filter unauthorized DHCP and ARP packets in your network.

IP source guard uses a binding table to distinguish between authorized and 
unauthorized DHCP and ARP packets in your network. A binding contains these 
key attributes:

• MAC address
• VLAN  ID
• IP address
• Port  number

When the Switch receives a DHCP or ARP packet, it looks up the appropriate MAC 
address, VLAN ID, IP address, and port number in the binding table. If there is a 
binding, the Switch forwards the packet. If there is not a binding, the Switch 
discards the packet.

The Switch builds the binding table by snooping DHCP packets (dynamic bindings) 
and from information provided manually by administrators (static bindings).

IP source guard consists of the following features:

• Static bindings. Use this to create static bindings in the binding table.
• DHCP snooping. Use this to filter unauthorized DHCP packets on the network 

and to build the binding table dynamically.

• ARP inspection. Use this to filter unauthorized ARP packets on the network.

If you want to use dynamic bindings to filter unauthorized ARP packets (typical 
implementation), you have to enable DHCP snooping before you enable ARP 
inspection.