Delta DVS-328 series User Manual page 41

D V S M a n a g e d I n d u s t r i a l R a c k Mo u n t E t h e r n e t S wi t c h U s e r Ma n u a l
DHCP snooping steps:
1. A DHCP client sends a DHCP request via the broadcast.
2. When a switch (relay agent) receives the DHCP request, it will add DHCP option-82 to the packet. DHCP
option-82 includes the MAC address of the host which sends a DHCP request (remote-ID sub-option) and
the interface ID on the switch which connects to the host (circuit-ID sub-option).
3. If the switch has configured an IP address, the IP address will be added to the DHCP packet.
4. If a DHCP server supports option-82, after the DHCP server receives the DHCP request, it will allocate the
IP address numbers according to the remote-ID sub-option or circuit ID sub-option.
5. A DHCP server responds to the switch via the unicast. And the switch checks whether the remote-ID or the
circuit-ID in option-82 matches the value of the DHCP request, and makes sure it sends from the
certificated DHCP server. Then it removes the information of option-82, and sends back to the interface on
the switch which sends the DHCP request.
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DHCP L2 Relay Global Configuration
You can enable or disable a DHCP relay function, and configure the parameters of the circuit ID sub-option
(the interface ID on the switch which connects to the host) and the remote ID sub-option (the MAC address
of the host which sends DHCP request) on this page.
DHCP L2 Relay Global Configuration
Admin Mode
Specify whether the global status of the DHCP relay is enabled.
 Enable: The DHCP relay function is enabled.
 Disable: The DHCP relay function is disabled. This is the default setting.
DHCP L2 Relay VLAN Configuration
VLAN ID
If you have added VLANs on the VLAN Configuration page, the VLANs can be
shown in the VLAN ID column, and you can configure the DHCP L2 relay
setting of each VLAN.
Admin Mode
Specify whether the status of the DHCP relay is enabled on the VLAN:
 Enable: Enable the DHCP relay on the VLAN. You can configure the VLAN
DHCP relay settings if the DHCP relay is globally disabled. But the settings
do not take effect even if you have applied it.
 Disable: Disable the DHCP relay on the VLAN.
Circuit ID
Specify whether the DHCP relay agent information option (DHCP option 82) is
enabled:
 Enable: Enable the relay agent information option.
3 - 2 0
Description
Description
Factory default
Disable
Factory default
1
Disable
Disable