ZyXEL Communications XGS-4526 사용자 설명서

Chapter 26 IP Source Guard

XGS-4526/4528F/4728F User’s Guide

The following table describes the labels in this screen.

Use this screen to enable DHCP snooping on each VLAN and to specify whether or 
not the Switch adds DHCP relay agent option 82 information (

) to DHCP requests that the Switch relays to a DHCP server for each VLAN. To 

Table 81   DHCP Snooping Port Configure

Port

This field displays the port number. If you configure the * port, the 
settings are applied to all of the ports.

Server Trusted 
state

Select whether this port is a trusted port (Trusted) or an untrusted 
port (Untrusted).

Trusted ports are connected to DHCP servers or other switches, and 
the Switch discards DHCP packets from trusted ports only if the rate 
at which DHCP packets arrive is too high.

Untrusted ports are connected to subscribers, and the Switch discards 
DHCP packets from untrusted ports in the following situations:

• The packet is a DHCP server packet (for example, OFFER, ACK, or 

NACK).

• The source MAC address and source IP address in the packet do 

not match any of the current bindings.

• The packet is a RELEASE or DECLINE packet, and the source MAC 

address and source port do not match any of the current bindings.

• The rate at which DHCP packets arrive is too high.

Rate (pps)

Specify the maximum number for DHCP packets (1-2048) that the 
Switch receives from each port each second. The Switch discards any 
additional DHCP packets. Enter 0 to disable this limit, which is 
recommended for trusted ports.

Apply

Click Apply to save your changes to the Switch’s run-time memory. 
The Switch loses these changes if it is turned off or loses power, so 
use the Save link on the top navigation panel to save your changes to 
the non-volatile memory when you are done configuring.

Cancel

Click this to reset the values in this screen to their last-saved values.