ZyXEL Communications XGS-4528F, Руководство пользователя, Страница: 272 / 491

Chapter 26 IP Source Guard
XGS-4526/4528F/4728F User’s Guide
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The following table describes the labels in this screen.
26.5.2 DHCP Snooping VLAN Configure
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 (
Chapter 41 on page
361 ) to DHCP requests that the Switch relays to a DHCP server for each VLAN. To
Table 81 DHCP Snooping Port Configure
LABEL DESCRIPTION
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.