ZyXEL Communications XGS-4728F - Manual (Page 244)

Chapter 26 IP Source Guard
XGS-4728F User’s Guide
244
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 36 on page
303 ) to DHCP requests that the Switch relays to a DHCP server for each VLAN. To
Table 80 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.