ZyXEL Communications MES3500-24 用户手册
Chapter 26 IP Source Guard
MES3500-24/24F User’s Guide
225
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 (
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 Advanced Application >
IP Source Guard > DHCP Snooping > Configure > VLAN.
IP Source Guard > DHCP Snooping > Configure > VLAN.
Figure 117
DHCP Snooping VLAN Configure
The following table describes the labels in this screen.
Table 79
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.
of the ports.
Server Trusted
state
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.
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:
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.
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.
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.
Table 80
DHCP Snooping VLAN Configure
LABEL
DESCRIPTION
Show VLAN
Use this section to specify the VLANs you want to manage in the section below.
Start VID
Enter the lowest VLAN ID you want to manage in the section below.