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WEB INTERFACE
To configure DHCP Snooping:
1. Click Configuration, Security, Network, DHCP, Snooping.
2. Set the status for the global DHCP snooping process, and set any ports
within the local network or firewall to trusted.
3. Click Apply
Configuring DHCP Relay and Option 82 Information
Use the DHCP Relay Configuration page to configure DHCP relay service for attached host
devices. If a subnet does not include a DHCP server, you can relay DHCP client requests to
a DHCP server on another subnet.
When DHCP relay is enabled and the switch sees a DHCP request broadcast, it inserts its
own IP address into the request (so that the DHCP server knows the subnet of the client),
then forwards the packet to the DHCP server. When the server receives the DHCP request, it
allocates a free IP address for the DHCP client from its defined scope for the DHCP client's
subnet, and sends a DHCP response back to the switch. The switch then broadcasts the
DHCP response to the client.
DHCP also provides a mechanism for sending information about the switch and its DHCP
clients to the DHCP server. Known as DHCP Option 82, it allows compatible DHCP servers
to use the information when assigning IP addresses, or to set other services or policies for
clients.
Using DHCP Relay Option 82, clients can be identified by the VLAN and switch port to which
they are connected rather than just their MAC address. DHCP client-server exchange
messages are then forwarded directly between the server and client without having to flood
them to the entire VLAN.
In some cases, the switch may receive DHCP packets from a client that already includes
DHCP Option 82 information. The switch can be configured to set the action policy for these
packets. Either the switch can drop packets that already contain Option 82 information, keep
the existing information, or replace it with the switch's relay information.
PATH
Configuration \ Security \ Network \ DHCP \ Relay
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