ZyXEL Communications XS3800-28, User Manual, Page: 615 / 789

Chapter 83 DHCP Snooping
XS3800-28 User’s Guide
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The following table describes the labels in this screen.
83.5 DHCP Snooping VLAN Setup
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 open this screen, click SECURITY > IPv4 Source Guard > DHCP Snooping > DHCP Snp. VLAN Setup .
Table 328 SECURITY > IPv4 Source Guard > DHCP Snooping > DHCP Snp. Port Setup
LABEL DESCRIPTION
SLOT This field appears only in Stacking mode. Click the drop-down list to choose the slot number
of the Switch in a stack.
Port This field displays the port number. In Stacking mode, the first number represents the slot ID
and the second is the port number. Please note that the default stacking ports (the last four
ports of your Switch) cannot be configured. They are reserved for stacking only.
* Settings in this row apply to all ports.
Use this row only if you want to make some settings the same for all ports. Use this row first to
set the common settings and then make adjustments on a port-by-port basis.
Note: Changes in this row are copied to all the ports as soon as you make them.
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.